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I. Comparative PsychologyHolland H. Waters and Bradford N. Bunnell


II. Physiological PsychologyClifford T. Morgan


III. Constitutional PsychologyW. L. L. Rees


IV. Existential PsychologyRollo May and Sabert Basescu


V. Applied PsychologyAnne Anastasi


Five major fields of psychology are described under this heading; other major fields are described under Clinical psychology; Counseling psychology; Educational psychology; Learning; Perception; Personality; Social psychology.The subject matter traditionally referred to as experimental psychology is found in the article onphysiological psychologyunder this heading, as well as in Drives; Experimental design; Forgetting; Learning; Motivation; Perception; Thinking.Important and large-scale psychological theories are discussed in Field theory; Gestalttheory; Learning, articles onclassical conditioningandinstrumental learning; Learning theory; Psychoanalysis; Thinking, article Oncognitive organization and processes.


Comparative psychology is concerned with the behavior of different species of living organisms. While some work is occasionally done with plant life, the field is typically limited to the behavior of animals. Its investigations lead to the specification of similarities and differences in behavior between species. These findings are of interest because it is assumed that they are correlated with the animals’ positions on the phylogenetic scale. Interspecific comparisons should thus provide a means of relating an animal’s behavior to its evolutionary background and contribute an important kind of information to psychology.

The accomplishments of the field have not, thus far, completely matched expectations. During the past century a vast amount of data on the behavior of infrahuman animals has been accumulated, but only a small fraction of this information has been used, or indeed proven useful, for comparative purposes. This has led some to deny the existence of comparative psychology as a distinct content area, and many more have used the title simply as the name for a method of study.

Since World War n, interest in comparative psychology has increased sharply. Some of the current trends in thinking and research that are beginning to revitalize comparative psychology will be presented in the sections below. For the purpose of this introduction, however, a few comments on some of the major characteristics of the field are in order.

(1) The term comparative psychology has often been used indiscriminately to include all work done on the behavior of infrahuman animals. Such animals are frequently used in behavioral studies because it is impractical, for economic or humanitarian reasons, to use human subjects and because the use of animals may be necessary in order to achieve an acceptable level of experimental control. There is nothing inherent in this practice to justify calling it comparative psychology. Such studies typically have as their objective the analysis of a particular behavioral process, the animal subject being nothing more than a convenient vehicle for that behavior. The assumption implicit in this procedure is that the principles of behavior found in a particular species are relevant for all animals. This assumption is tempered somewhat by the circumstances that mammals are commonly used in such studies and that generalizations are usually made only to other mammals. Nevertheless, the assumption remains, even though it is this very assumption that comparative psychology is supposed to test. The point is, then, that some of what has been called comparative psychology is not only not comparative psychology but, in addition, assumes the validity of the evolutionary hypothesis on which the rationale for a comparative psychology is based.

(2) A second characteristic of comparative psychology is related to the first: from the beginning, comparative psychology has been highly anthropocentric in its orientation. In spite of the fact that man may be looked upon as just another species in the study of the evolution of behavior, he has not often been viewed in that way. Instead, comparative psychology has concentrated on the goal of achieving a better understanding of man through the study of the behavior of lower animals. This goal, which provided the original raison d’être for comparative psychology in Darwin’s time, has continued to overshadow all others throughout the history of the field.

(3) The application of comparative methodology in comparative psychology has been very different from its application in other biological fields. For example, in classical zoological work concerned with the phylogenetic development of structure and function, comparisons are typically made between species within a genus. Except in the growing field of behavior genetics, little behavioral work has been done within genera and interspecific comparisons are usually made only across broad taxonomic groups—for example, a species of fish is compared with an amphibian, a reptile, or a mammal. The comparative psychologist’s procedure is thus quite gross; he tends to select animals that are representative of relatively large morphological differences along the phylogenetic continuum. Therefore, the relationships sought by the comparative psychologist between an animal’s evolutionary background and its behavior are of a very general nature. He justifies this approach by pointing out that his major interest is in the causal analysis of behavior and only secondarily in the origins of behavior. Most of his data are relevant only to the former question. This approach is thus quite different from that of the ethologist, whose interest extends beyond causal analysis to include a primary concern with the evolutionary origins and adaptive significance of behavior. In ethology intrageneric comparisons have been used successfully in the identification and study of homologous behavior patterns.

(4) Finally, since the beginning of the twentieth century, comparative psychology has limited itself mainly to laboratory investigations. This practice developed out of a reaction against the anecdotal nature of much of the data collected during the latter half of the nineteenth century. These attempts to put behavior in a test tube, and to achieve rigorous experimental control, have been successful in producing reliable data and in reducing the teleological interpretations made by many early investigators. Comparative psychologists have been criticized on the grounds that many of their behavioral testing procedures, since they ignore the natural history of their subjects, do not provide an adequate sampling of the animal’s behavioral repertoires and may actually yield spurious results because they impose conditions that strain or exceed the limits of the animal’s capacities to respond. In response to this criticism, there has been a trend toward obtaining more and better information about an animal’s behavior capacities before bringing it into the laboratory. The emphasis on laboratory experimentation continues, however, and the use of field studies and investigation of behavior under conditions and situations designed to give the animal full opportunity to express his “natural“responses serve to complement, rather than to supplant, the laboratory work.

Historical aspects

It has been pointed out that man’s interest in animal behavior is very nearly as old as man himself and that such information may well have been essential in order for man to eat and to avoid being eaten (Hale 1962). From a philosophical point of view, Aristotle taught that human and infrahuman behavior can be directly compared, that such characteristics as “gentleness or fierceness, mildness or cross temper, courage or timidity, fear or confidence, high spirit … or low cunning, and …sagacity“can be observed in animals below man (Historia animalium 588a). Such a belief was almost certainly a product of Aristotle’s rational approach to man and nature rather than the result of the application of the observational techniques he defended in other connections. Aristotle’s view yielded to the doctrine of “special creation“and the belief in qualitative differences between animals and men. It was not until this latter belief was challenged by the Darwinian theory of evolution that the seeds were sown for the development of contemporary comparative psychology.

The Darwinian theory denied the “special creation“explanation of the origin of man, erased the Cartesian dichotomy between besouled man and the soulless and mindless animal, and thus elevated the importance of animal study as a source of data for supporting evolutionary hypotheses. In order to demonstrate evolutionary continuity, it was necessary to show that man possessed many of the simpler, “brute“instincts present in lower animals and to show that these animals, in turn, exhibited capacities for reasoning, emotional behavior, social organization, and communication. That man and animals possess the simpler forms of behavior in common was never a matter of serious controversy, although later debates over the validity of the instinct concept are related to this question. Of greater importance was the search for higher mental processes in infrahuman animals. Examples of the first attempts to gather this sort of data are to be found in the writings of G. J. Romanes (1883). Such materials were largely anecdotal, however, and were harshly criticized because neither the validity of the observations reported nor the adequacy of the resulting interpretations could be checked by other workers. Demonstration of evolutionary principles was more a matter of anthropomorphic argument than scientifically derived fact.

Within experimental psychology, Wundt had championed the comparison of the behavior of man and animals as a means of better understanding man ([1864-1865] 1907, pp. 11, 340). Wundt thus threw the weight of his authority and position in psychology behind any future movement making the psychology of animals respectable. [SeeWundt.]

It was in this context that comparative psychology emerged as a highly anthropomorphic, anthropocentric area of investigation. The first major modification of this approach occurred in the 1890s. Loeb’s tropism theory (1918), while not denying the animal mind, represented a return to the mechanistic view of Descartes. In 1894 C. Lloyd Morgan’s “canon“appeared. This was a formulation of the principle of parsimony for the interpretation of animal behavior: “In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of the exercise of one which stands lower in the psychological scale“([1894] 1906, p. 53).

Together, Loeb and Morgan may be regarded as the fathers of scientific comparative psychology. Their writings stressed an objective approach and pointed the way to the use of experimental procedures in gathering data on animals (Warden 1927). It is important to note, however, that while anecdotalism was eliminated, the questions under study changed very little. Despite the new experimental fervor, investigators were still primarily concerned with describing the animal mind or consciousness, and with charting its evolutionary course. It was not until the arrival of behaviorism, some twenty years later, that the subject matter of comparative psychology shifted from the study of consciousness and volitional choice to the study of behavior qua behavior.

In the meantime, another development had occurred which was to have an important influence on the developing field. Thorndike, in his Animal Intelligence: Experimental Studies, came to the conclusion that all vertebrates “manifest fundamentally the same sort of intellectual life“([1898-1901] 1911, p. 283). He found no important differences in the manner in which fish, reptiles, birds, and mammals learned the solutions to problems. The difference between a fish and a monkey was quantitative rather than qualitative—the monkey could form more complex associations more quickly and could retain them better than the fish. Man’s intellect was said to be a further elaboration of the same sort of associative processes. This hypothesis was emphasized by Watson, and many came to accept the idea that the laws of learning were fixed and that there were no qualitative discontinuities in animal learning. This belief justified the use of rats and other infrahuman animals as human surrogates and tended to discourage comparative research. [SeeWatson; Thorndike.]

Not everyone accepted Thorndike’s conclusion, and some argued that although animals might not differ much in the capacity for simple associative learning, they might show significant differences on more complex tasks involving ideational or symbolic processes. Animals were tested on delayed response, double alternation, multiple choice, insight, and other such problems. Unfortunately, difficulties in providing standardized test situations and finding methods of quantifying the data were never resolved. By 1940 this approach had about died out. In consequence, at least in the United States, the study of animal behavior no longer carried the flavor of a compafative approach.

A paper by Beach (1950) appeared as a protest against the then unsatisfactory status of comparative psychology. It had become almost exclusively limited to studies of the animal, with few, if any, applications of comparative methodologies. Animals were used as tools, or instruments, for the testing of different hypotheses about behavior that could not be tested on human subjects.

With the publication of Tinbergen’s The Study of Instinct (1951) psychologists in the United States became increasingly aware of studies conducted by European scholars who referred to their area of research as ethology. The rapid postwar development of the field of ethology exerted a most important influence on the course of comparative psychology. These students of animal behavior were not interested in stopping with causal analyses of behavior. Their major objective was the determination of the way in which behavior evolved, and to this end they stressed the adaptive significance of certain species-specific behavior patterns. Presumably behavioral differences can arise in two ways: through genetic transmission during the evolution of the species and through learning during the ontogeny of the individual. For the ethologists, the most important behavioral elements were the highly stereotyped, relatively unmodifiable motor patterns, which were presumed to be innate and which were held to be the key to the evolution of behavior. These concepts, and the theories of instinctive behavior that were derived from them, clashed violently with the ideas of American psychologists who emphasized the importance of environment and experience. The past ten years, beginning with Lehrman’s criticism (1953) of Lorenz’ instinct theory, have witnessed a lively international debate between psychology and ethology. [For a typical rebuttal by the ethologists, see Eibl-Eibesfeldt & Kramer 1958, pp. 204-207; see alsoEthology.]

Both fields have benefited from this debate. Following the lead of the psychologists, ethologists are now showing serious concern with the ontogeny of behavior, while ethology has stimulated psychology to a renewed interest in the field of behavior genetics. All the differences between the two have not yet been resolved. Arguments concerning the innateness of behavior, for example, may be expected to persist for some time.

These two events, Beach’s protest on the negative side and the work of the ethologists on the positive side, have helped to revive interest in comparative psychology among American students.

Evolution—structure and function

An increase in behavioral capacity presumably accompanies an increase in anatomical complexity. This generalization is usually true, although in some cases the presence of structural elements may have no apparent behavioral significance. For example, despite the presence of color receptors in the eye of the cat, it has been extremely difficult to demonstrate that this animal has functional color vision. Futhermore, an increase in behavioral complexity may appear without any apparent accompanying structural changes. Resolution of these problems will be, at least in part, dependent upon the development of better tests of behavioral “complexity“and upon improvement of anatomical, physiological, and chemical techniques applicable to the identification of structural changes in development.

With respect to the evolution of behavior, the problem of relating structure and function is difficult when function is defined in terms of the molar classifications that behavior psychologists generally use, such as learning, motivation, perception, etc. (In contrast, ethologists have emphasized a molecular behavioral unit, the “fixed action pattern,“in their more successful attempts to trace the evolution of some aspects of behavior: e.g., Lorenz 1958.)

Since behavior does not exist in fossil form, an additional difficulty is that evidence for the evolutionary course of behavior is necessarily indirect. It must also be recognized that the behaviors available for study are exhibited by highly specialized creatures that structurally, and presumably behaviorally as well, differ considerably from the ancestral source of the evolutionary branch. [SeeEvolution, especially the article onevolution and behavior.]

Comparative psychologists have tended to emphasize central, as opposed to peripheral, mechanisms. Within any broad taxonomic group, such as a phylum, or even a class, there typically exists a tremendous range of sensory and motor development. For example, the visual systems of coelenterates range from pigmented dermal spots to relatively sophisticated lens eyes (Maier & Schneirla 1935). Across phyla there are many instances in which a particular representative of a ’lower” position may be better equipped for receiving a particular kind of energy than a representative of a “higher” group; for example, many arthropods have color vision, while many mammals apparently do not. While a number of investigators have been interested in the functional correlates of different types of peripheral systems, those psychologists who study learning, motivation, and perception stress the role of the central nervous system and typically concern themselves only with making certain that sensory information is reaching the animal and that the overt responses being measured are within its behavioral repertoire. Their interest is in how the animal uses the information it receives and in what effect the information has on the response system. They usually assume some sort of intervening process, or processes, mediated by the internuncial structures of the organism. “Intelligence” is typically thought of as such a central process that is highly correlated with the level of neural organization possessed by the organism. This is the working hypothesis behind much of American comparative psychology [see“Learning,”below; see alsoNervous system, article onstructure and function of the brain; Senses.]

These factors go a long way toward explaining the fact that in comparative psychology comparisons are typically made across broad groups, a procedure that is not employed by the zoological taxonomist and one that is not very useful for the delineation of the phyletic history of a given bit of behavior. The procedure may be justified, however, on the grounds that these are comparisons between representatives of different levels of neural organization and that this is a most useful type of information, particularly when one considers the categories of behavior in which the psychologist is most typically interested.

Instinct, ontogeny, and motivation


Beginning in the 1920s the entire discipline of psychology underwent what has been called the “anti-instinct” revolt (Beach 1955). The major objection was to the use of instinct as an explanatory concept. It was pointed out that calling a behavior an instinct did not in any way demonstrate the causes of that behavior and that the use of such a label tended to keep people from doing the research necessary to determine causal factors. It was felt that if such research were done, the behavior would prove amenable to analysis in behavioristic terms and that the instinct concept was superfluous (Kuo 1924). In support of this position, it was possible to point to work such as that of Kuo (1930), who analyzed the rat-killing “instinct” of the cat and showed it to be heavily dependent upon the past history of the organism. The cat’s behavior, with respect to rats, could be modified extensively, and a wide range of responses to rodents could be developed. This and similar studies fit well with the contemporary behavioristic emphasis upon behavioral plasticity and the importance of experience and learning. In terms of the interests of psychologists, many “instinctive” behaviors could be considered as little more than special applications of the principles being generated in the learning laboratories. The net result of all this was to banish the instinct concept from psychology. Along with it, with a few significant exceptions, went most of the interest in behavior genetics and in the study of behavioral constancy. Conceptually, the essential importance of accepting an epigenetic interpretation of instinctive behaviors, an interpretation that stresses the interaction between heredity and environment, was recognized (Carmichael 1927). In actual fact, psychologists emphasized experiential factors to the exclusion of almost everything else.

In the 1950s the debate over the instinct concept arose once more, stimulated in large part by the work of the ethologists. The central question again was whether or not instinct, if there was such a thing, was a meaningful class of behavior. Instinctive behavior, defined essentially as the product of innate neural patterns laid down by the genetic constitution of the organism, was the basic behavioral datum for the program of the ethologists. Given the evolutionary interests of ethology, behavior that was typical of a species commanded its greatest attention. [SeeInstinct.]

American psychologists once again reacted negatively to the instinct concept and again defended the hypothesis of an interaction between genetic constitution and experience; “instinct” could not be either learned or inherited. As has been noted, the net result of the entire debate was a shift of emphasis to studies of the ontogeny of behavior and a reawakened interest in behavior genetics. [SeeGenetics, article ongenetics and behavior.]

An example of the contemporary American approach to the study of instinctive, or species-typical, behavior patterns is the work of Lehrman on the analysis of the reproductive behaviors of the ring dove (for summaries of this work, see Lehrman 1932; 1964). He has been able to demonstrate experimentally several of the mechanisms by which hormonal-environmental interactions give rise to the expression of complete behavior patterns. In doing this, Lehrman (1962) has called attention to the fact that experience may have an effect on behavior—by altering rates of growth, producing changes in sensitivity, facilitating behaviors that occur later in a sequence, etc.—which does not fit the standard definitions of ’learning,“but which nevertheless can be crucial for the normal development of the behavior pattern. The generalization is drawn that learning and heredity cannot be meaningfully distinguished, and the traditional view that learning is dominant in higher animals and instinct in lower animals is no longer considered valid by most investigators. Some, however, still find the dichotomy useful (e.g., Thorpe 1956). Schneirla puts the situation in these words :

…heredity influences all behaviour in all animals, its influence is more direct in some animals (evidently the more primitive) than in others and may be very different on different phyletic levels. … [It is] likely that behaviour evolves through new and increasingly complex reorientations, with the old rebuilt and extended in terms of the new, [rather] than through the replacement of the “innate“by the ’learned.”

…[It] is therefore probable that the relationship of behaviour to survival, always important in evolution, is very different on various phyletic levels. As it is realized that assumptions of innateness in apposition to the acquired can explain no activity, increasing emphasis is placed upon the need for analytical investigation. (1963, p. 692)


In addition to the ontogenetic approach, which constitutes the mainstream of American comparative psychologists’ work with species-typical behavior patterns, there is a continuing interest in ontogenetic development for its own sake. This is reminiscent of the traditional stress by Freud and Watson on the effects of the early history of the organism.

Beach and Jaynes (1954) cite the following examples of animal studies in this area that serve as an indication of the scope of the work on the effect of early experience: rats, pigeons, and chimpanzees, raised in darkness, exhibit marked but not permanent disturbances in later visual adjustments; the appearance of normal motor activities in chimpanzees raised under conditions of restricted movement is temporarily delayed; chickens raised in the dark and prevented from pecking are less accurate in pecking but rapidly improve with practice; some evidence of a “need to suck” is reported when puppies are deprived of the sucking activity; the effects that depriving infant rats of food and water has on their hoarding of food and water as adults are somewhat ambiguous; egg-laying behavior in some species of insects can be elicited by other than the normal host when they are raised on a nonpreferred host; mating behavior in certain species of fish, ring doves, and pigeons can be elicited by a species different from their own when the former are raised alone or with the foreign species; reproductive behavior of such mammals as rats, the American bison, antelopes, and others is modified under conditions of captivity; species recognition and gregariousness in insects, birds, and domestic chicks are subject to modification through early experiences, as is song acquisition in birds; social behaviors in the dog, in the lambs of both wild and tame sheep, and in chimpanzees are all modifiable during early infancy; wildness and aggressiveness, and the ability to adapt to differing learning situations, in rats have been modified by “gentling” procedures and by varying the type of environmental conditions present during infancy.

Contemporary examples of research in this area, to mention only a few, are the work of Scott and Marston (1950) on the effects of early experience on the development of adult behavior in dogs, which called attention to the presence of critical periods in that development; the studies of imprinting, which also emphasized the critical-period concept (see Hess 1959); the studies of stress effects (e.g., Levine 1962); and Harlow’s (1958) work on affectional responses in infant monkeys.

A model proposed by Fuller and Waller (1962) brings together some of the explanations that have been proposed to account for early experience effects. One set of explanations rests on the concept of learning: ability to learn a specific type of response may change with age, a change that cannot at present be correlated with any known neuro-physiological change; it may also be that what the results show is the persistence of early habits resulting from such conditions as change in drive, amount and kind of reinforcement, lack of interfering or competing habits, or similar influences.

A second set of explanations rests on the concept of maturational changes. Such changes may be inferentially applied to the learning changes given above; they may contribute to the structural and neurophysiological conditions underlying sensory, neural, and muscular equipment employed in specific responses because of stimulation during early experience; and, lastly, the finding of so-called critical periods in development, times during which mastery of particular acts or the effect of stimulation is more marked, may be a reflection of the fact that the systems supporting such activities have reached maturity.

A third set of concepts is couched in terms of the relatively greater sensitivity of the young organism to all sorts of physical and chemical variation. Presumably, then, they are more susceptible to nonspecific stresses in early life and might as a result undergo permanent modifications in basic physiological functions. Such alterations in metabolic, autonomic, and endocrine systems would be expected to produce variations in adult behavior patterns. [SeeInfancy.]


The approach to many of the problems of the energizing and directive processes operative in such maintenance activities as feeding, drinking, and reproduction has already been mentioned. The current emphasis is upon the analysis of the entire behavior pattern, rather than on the measurement of the amount of consummatory activity alone. Aronson (1959), for example, has pointed out that phylogenetic trends in the relationships between sex hormones and reproductive behaviors are often discernible only when careful attention is paid to the individual components of the behavior pattern. When motivation is considered in terms of consummatory behavior, as Ratner and Denny (1964, chapter 9) point out, the higher an animal is on the phylogenetic scale, the greater is the variety of stimulation that can elicit or control the behavior. Studies of the sexual behavior of male mammals below the primates (e.g., Hale & Alm-quist 1956; Fisher 1962) have shown that ungulates, and even rodents, are very responsive to stimulus variation. A similar trend with regard to the operation of experiential effects is illustrated by work on cats (Rosenblatt & Aronson 1958), rats (Zimbardo 1958), and guinea pigs (Valenstein, Riss, & Young 1955). While this work generally supports the notion that increasing behavioral flexibility accompanies increases in phylogeny, perhaps the most interesting finding of all has been that environmental and experiential influences are more ubiquitous and are of critical importance further down the scale than had previously been thought.

In the past, feeding, drinking, and sleeping have been investigated more by zoologists and physiologists than by comparative psychologists. Newer methods of approach, particularly those which have made the central nervous system accessible to experimental approach, now seem to be leading to increased interest in comparative studies of these fundamental processes.

Beyond the study of basic maintenance functions, the work of Butler (1953) on exploratory drives and of Harlow and his associates (e.g., Harlow, Harlow, & Meyer 1950; Harlow & Mc-Clearn 1954) on the manipulative drive in monkeys suggest evidence for “supraphysiological” drives, at least in higher animal forms. Berlyne (1960) provides a good discussion of curiosity and investigative motives as “higher” drives. Finally, the idea that some drives may be learned (Miller 1951) and that motivated behavior may be controlled by secondary reinforcement mechanisms is widely accepted. Presumably such learning is more characteristic of the higher animals. [SeeDrives; Motivation; Stimulation drives.]


The field of learning has traditionally been the major area of interest in American comparative psychology. In fact, this emphasis has resulted in the strongest criticism of comparative psychology by other students of animal behavior. Many feel that significant aspects of the animal’s behavior are often missed completely or are given an erroneous interpretation because of the concentration on only one facet of behavior.

There are several problems involved in the learning area. The first is the definition of learning itself. The emphasis in much of the work of comparative psychologists has been upon classical conditioning and instrumental learning paradigms. The establishment of a link between a stimulus and a response is, however, only one of the ways by which organisms modify their behavior as a result of environmental change or as a consequence of their past activities. Many of the techniques by which the organism adapts to its environment are not “true” learning. Fatigue effects represent one such example. While fatigue may not be hard to understand, the phenomena of sensitization and habituation, which typically have been controlled out of laboratory learning situations as being unwanted “noise,” cannot be disregarded so easily. These types of behavioral modification appear to be universal in the animal kingdom and deserve more attention than they have been given as possible precursors of true associative learning. It is probable that as psychologists conduct more studies on the invertebrates, these phenomena will be more carefully analyzed. Such emphasis is deserved since, at the mammalian level, studies (reviewed in Livingstone 1959) have clearly demonstrated central nervous control of peripheral sensory processes, which appears to be a critical mechanism in habituation. Other special phenomena, such as provisional orientation (Maier & Schneirla 1935), imprinting (Hess 1959), and the type of behavioral modification shown by Lehrman’s ring doves, are being given the increased attention they merit. [SeeFatigue; Imprinting; Learning.]

A second problem is the question of the lowest phyletic level at which learning occurs. This problem has been attacked using the traditional paradigms for associative learning. At present it is certain that arthropods and at least some mollusks are capable of such learning. Also, the evidence is good that annelids and flatworms can be trained by means of both classical conditioning and instrumental techniques (Jacobson 1963). Below this level reports of learning are not convincing, although the reader is referred to the work of Gelber (1952) and of Jensen (1957) for a debate over the presence of associative learning in one-celled animals. Questions for future study will be: whether there is any difference in the relative primitiveness of classically, as opposed to instrumen-tally, conditioned responses; and whether the various types of learning, as now defined, are mediated by the same neural and/or chemical processes. It is at least possible that the same result, in terms of a learning proficiency score, is obtainable through more than one mechanism.

A third problem is the search for the relationship between phyletic position and learning capacity. In general, it has been found that as one ascends the phylogenetic scale there is a corresponding increase in the ability of organisms to modify their behaviors when they are subjected to environmental changes. This behavioral plasticity is revealed by the fact that “higher” animals are able to learn more complex problems than are “lower” forms. However, this generalization has frequently broken down, for there are many reports in which no apparent differences have been revealed between representative phyla or classes, and some instances in which “lower” forms surpassed “higher” forms in performance on learning tasks. It is this sort of finding that challenges the evolutionary hypothesis of behavioral development. It does not disprove such a hypothesis, but it does mean that close attention must be paid to the situations in which the tests are conducted and to the methods used in obtaining the scores that are to be compared. [SeeLearning, article onlearning in children.]

A partial resolution of conflicts between evolutionary theory and data is found when one explores the proposition that certain “lower” species may have evolved highly specialized abilities to learn particular things in particular situations. It is part of the task of the comparative psychologist to recognize such occurrences and to try to identify the mechanisms that mediate their appearance.

The acknowledgment of species-specific learning capacities does not help very much in demonstrating a general relationship between phyletic position and learning capacity, however. As has been noted, Thorndike’s failure to find differences in the problem-solving performance of many different species diverted many from the use of comparative methods. The finding that if an animal could do a simple learning task at all, it could do it about as well as any other animal was repeatedly corroborated.

Some investigators, however, felt that differences between species might become apparent if more complex tests of animal “intelligence” were used. Delayed-response, multiple-choice, and double-alternation problems were among the many early tests devised to tap the higher mental processes of animals. More recently, such techniques as complex multiple-cue tasks (such as oddity, matching, and conditional-discrimination problems), probability-matching techniques, and both reversal learning-set and discrimination learning-set problems have been introduced.

In the interpretation of results of comparative studies of learning a useful distinction can be made between quantitative and qualitative comparisons of performance. Almost all the early work consisted of attempts at quantitative comparison. Typically, scoring was on a continuum of some sort (number of seconds of delay possible, number of errors, running time, trials to criterion, etc.), and the idea was that different species ought to fall at different places on such a continuum. Since interspecific differences in sensory and motor capacities, to say nothing of motivational-emotional factors, are frequently considerable, the investigator who uses such an approach is faced with the difficult task of defining standard test situations and scoring procedures.

A study by Schneirla (1946), in which the maze performance of rats and ants was compared, provides an illustration of what is meant by qualitative comparison. Schneirla demonstrated that rats learned more quickly than ants (a quantitative difference), but he emphasized his discovery that the way in which ants went about learning the maze was very different from the processes exhibited by the rats. Ants learned one section of the maze at a time, and the learning of one section resulted in an increase in errors on succeeding sections, as if the maze were “new” after each portion of the maze was completed. In addition, the ants eliminated blind alleys in the maze differently than did the rats, making successively shallower penetrations into cul-de-sacs while the rats tended to eliminate each wrong entry in an all-or-none fashion. When the maze was reversed after learning had been completed, the rats showed considerable savings, but ants acted as though the situation were totally new and had to be relearned from the beginning. Finally, ants did not show any goal gradient effect (earlier elimination of the blinds near the goal), while the rats did. Thus, a meaningful differentiation between the two species could be made on qualitative grounds in terms of how the animals went about learning and of what was learned. Bitterman (1960) and his associates have been among the first to adopt this qualitative approach. They have, for example, shown that the “Humphreys effect” (greater resistance to extinction after training under partial, as compared with continuous, reinforcement) does not occur in fish in the same manner as it does in rats. This indicates that, for fish, the relationship between the outcome of a response (its reinforcement) and the response is much more direct, and presumably simpler, than in higher vertebrates.

A current trend in the comparative psychology of learning thus emphasizes a search for qualitative differences—a comparison of animals in terms of the extent to which they follow the same principles in their learning and whether the functions plotted from raw scores exhibit similar shapes or other characteristics. Warren (1965) has provided a comprehensive summary of both qualitative and quantitative comparative data on vertebrate learning performance.

A final problem, cutting across all of the problems mentioned so far, is that of finding ways of equating testing situations so that comparisons can be made. As was noted earlier, the experimenter cannot be sure that in a “standard” situation an animal of one species can receive the same sensory information as one of another species, can perform the response with equal facility, or is similarly motivated. Failure to control these conditions can prevent any meaningful comparisons. Unfortunately, except perhaps with animals that have very similar sensory and motor capacities, it is difficult to control these factors by equating the tasks at hand, and even were this done, the problem of equating motivational state and controlling for different ecological backgrounds is extremely difficult. The way around these difficulties, as proposed by Bitterman (1960), is to employ the method of control by variation. If, for example, the absence of the Humphreys effect in fish is duplicated under different motivational states, and over other testing situations, etc., it would be fairly safe to say that a meaningful difference exists between these animals—fish and rats—relative to this effect. It would not be necessary to argue that the animals were tested under “culture free” conditions.

Social behavior

In its broadest sense “social behavior” refers to behavior elicited by and directed toward another individual or group. Such behavior is clearly interactive when the behavior of the first individual is modified by the response of the second individual or group. Social behavior as thus defined may be readily observed taking place between individuals of different species: the sheepherder’s dog responds to signals given by his master as well as to the movements of the members of the flock; a predatory animal elicits “alarm” and “escape” or “defense” reactions from its potential prey; the mockingbird drives birds of another species away from its territory; and so on, with numerous other instances of interaction between species and between genera. More critical and significant for the purpose of the present review, however, is the social behavior taking place within species. It is from these studies that principles of group organization and types of social relationships are being uncovered.

A comparative psychology of social behavior should be interested in such general questions as: Where, on the phylogenetic scale, does social behavior first occur? What is the relationship between position on the phyletic scale and the types of social behavior observed? On what bases may a classification of social behavior be made so that such comparisons are possible for both phylogenetic and ontogenetic development?

With regard to the first question, one attempt at a solution has been to focus on the concepts of cooperation and competition. The animal sociologist W. C. Allee (1931; 1938) believed that even among simple organisms there exists an automatic, unconscious “protocooperation,” which is a fundamental biological principle. This principle says that at the level of the social group the interrelations between individuals in the group are more helpful than harmful. True social behavior is thought to have developed from animal aggregations which, while initially formed by nonsocial forces, survived because of advantages obtained through proximity. According to Allee, subsequent development followed a familiar pattern: “Each advance in complexity came from the natural selection of an increased ability in natural cooperation on the part of the evolving stock; the greater natural cooperation came first, then it was selected. Cooperation is a biological necessity both in individual evolution and in the evolution of groups” ([1938] 1951, p. 211). One very important factor was the evolution of the cooperative functions involved in sexual reproduction. Allee (1931) thought it likely that sex originally arose from interorganismic stimulation produced as a consequence of the aggregation of simple asexual organisms. The appearance of sexual reproduction thus provided for the appearance of the family, one of the basic units in true social groupings and social behavior.

Closely allied with the concept of cooperation has been the problem of competition between individuals and the ways that have been developed for handling aggressive behavior (e.g., territoriality, dominance-subordination relationships, and the like). Aggressive behavior occurs in some of the higher invertebrates, but with few exceptions studies of aggression and fighting have been confined to vertebrates. The role of aggressive behavior in vertebrates has been described in a classic paper by Collias (1944). A more recent summary of concepts and data in the area of competition and cooperation (as well as papers on reproductive behaviors, socialization, and the evolution of signaling devices) can be found in the book Social Behavior and Organization Among Vertebrates, edited by Etkin (1964).

It is quite possible that principles other than those of cooperation and competition underlie the evolutionary development of social behaviors, but alternative conceptual and theoretical models are not available.

The question of the relation between phyletic level and the types of social behavior present has received little systematic study. There are a number of studies dealing with the social behavior of a given species, but they have not been ordered in a fashion that permits an approach to the determination of the relation between phyletic level and types of behavior exhibited. Not all investigators in the area have shown a desire for a classificatory system of social behavior, many apparently preferring to take the behavior as they see it without attempting to force it into rigid categories. It is clear, however, that some sort of classification is necessary if the search for phylogenetic relationships is to be taken seriously.

The schema proposed by Scott is an example of an attempt at such a classification, and an example of its application for comparative purposes is available (1960, pp. 261-264). Tinbergen (1953) has provided an analysis of social behavior from the ethological point of view.

Neither the Scott nor the Tinbergen classification in itself implies anything about the mechanisms by which social behavior is established. In actual fact, Tinbergen emphasizes the innateness of such behaviors, while Scott has stressed a “socialization” concept in which the effects of experience are presumed to play an important role. Insofar as flexibility and the ability to learn are related to the complexity of social responses, it may be suggested that “higher” animals are capable of assuming a wider variety of roles and relationships and that these are more interchangeable than they are in “lower” forms. This generalization has not, however, been extensively tested. Finally, the development of language provides for a tremendous increase in the communications that are so essential to social behavior, giving a significant advantage in the potential for social behavior. [SeeSocial behavior, ANIMAL.]

Rolland H. Waters AND Bradford N. Bunnell

[See alsoEthology.Other relevant material may be found inCommunication, ANIMAL; Evolution; Genetics; Imprinting; Instinct; Sexual behavior, article onanimal sexual behavior; Social behavior, ANIMAL; and in the biographies ofDarwinandMorgan, C. Lloyd.]


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Hess, Eckhard H. 1959 Imprinting. Science 130:133-141.

Jacobson, Allan L. 1963 Learning in Flatworms and Annelids. Psychological Bulletin 60:74-94.

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Kuo, Zing Yang 1924 A Psychology Without Heredity. Psychological Review 31:427-448.

Kuo, Zing Yang 1930 The Genesis of the Cat’s Responses to the Rat. Journal of Comparative Psychology 11:1-35.

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Physiological psychology is the study of the physiological basis of behavior and mental life. In other words, it is concerned with the role of various organs of the body in psychological phenomena. Of these organs, the brain is clearly the most important, for it is the great coordinator and organizer of mental and behavioral events. The subdivision of physiological psychology concerned exclusively with the brain is known as neuropsychology—the title of the chair held by Karl Lashley at Harvard from 1937 until 1955. But other organs of the body also play important roles. These fall into two main categories: the sensory (receptor) systems and the motor (effector) systems. The motor systems include not only the skeletal and smooth muscles but also the endocrine glands. These latter, through their various effects on sensory and motor organs as well as on the nervous system itself, are proving to play an important role in the determination of behavior. Their role is, of course, biochemical. Also biochemical and included in physiological psychology are the influences of diet and of drugs. The general field of chemical influences on behavior has come to be called psychochemistry. That which is restricted to the effects of drugs is psychopharmacology. [SeeDrugs, article onpsychophar macology;Mental disorders, article Onbiological aspects; Nervous system; Senses.]

In principle physiological psychology covers both human and animal activities, but in practice it has been more concerned with animal behavior. This is because the techniques for studying physiological correlates in man are limited largely to clinical observations or measurements, and these are not so illuminating or powerful as the experimental methods that can be used with animals. For example, experimental surgery and both electrical stimulation and recording deep within the organs of the body are seldom possible with human beings, but they are with animals. Similarly, there are restrictions on the use of drugs and biochemical agents which apply to human beings but not to animals. The situation is changing somewhat as new techniques become available, and the special field that emphasizes physiological correlates of human psychological phenomena has recently been called psychophysiology.

Relationship to other fields

It should be noted that physiological psychology is related to three other fields: experimental psychology, psychobiology, and comparative psychology. Historically the term experimental psychology, introduced about 1880, meant the application of the experimental method to problems of psychology formerly addressed through philosophical reflection and observation. Today the term covers not only the method but the body of facts and principles acquired with the method. Since most of what is known in physiological psychology was learned from the experimental method, physiological psychology is largely a subdivision of experimental psychology.

Psychobiology was a term widely used in the first part of the twentieth century, and then it fell into disuse. It has recently been revived, particularly among biologists, with the flowering of interest in differences in behavior among species. Etymologically, psychobiology could very well apply to any and all relations between psychological and biological phenomena, including physiological psychology. But scientific usage, being determined by scientists rather than etymologists, has narrowed the term primarily to species differences in behavior. Thus, psychobiology refers to the study of the behavior often observed in natural settings or in quasi-experimental situations as it relates to the biological and genetic characteristics of the species under study rather than to the functions of internal organs of the body. The term ethology has been used by European zoologists to refer to this kind of psychobiology.

In the United States the term comparative psychology has come, at least among psychologists, to displace psychobiology. Comparative psychology, as the term implies, is supposed to be a comparison of the behavior of different species along the phyletic scale. However, because of the convenience and cheapness of the laboratory rat, so much of American comparative psychological research, until recently, was done with the rat that the term “comparative” was hardly justified. The situation has changed somewhat, but American experimental work with animal behavior is still better characterized as animal psychology than as comparative psychology. The ethology of the European zoologists is closer to the meaning of comparative psychology, even though it is more naturalistic and less exact than experimental animal psychology. [SeeEthologyandPsychology, article oncomparative psychology.]


Physiological psychology employs the methods of several fields but principally, of course, those of psychology and physiology. A typical experiment or study consists of correlating a psychological variable and a physiological variable. That is to say, any psychological experiment of interest may be combined with some physiological intervention. Since psychological experiments are well covered in other articles in this encyclopedia, only physiological methods will be discussed briefly here. These fall into four main groups: (1) neuroanatomical methods, (2) electrical recording, (3) stimulation methods, and (4) hormonal and biochemical methods.

Neuroanatomical methods usually consist first of some means of destroying some particular part of the nervous system and then of determining exactly what was destroyed so that the loss of a structure may be correlated with some behavioral variable. Destruction of a neural structure results in a lesion or an ablation, lesion being the more general and frequently employed term. Two methods of making lesions are in general use: (1) The classical method is one of open, or gross, surgery, in which the brain is exposed and the lesion is made by cutting or burning the structure of interest; (2) a newer and, for many purposes, more precise method that is particularly suited for work with deep structures is the electrolytic method. In this case the lesion is made by passing current through the tip of an electrode located in the structure of interest. To determine afterward what lesion has been made by one or the other of these methods, the brain is usually sliced, mounted on slides, and stained to show cells that have been destroyed or left intact. Because injury to any part of a neuron in the central nervous system causes destruction of the whole neuron, the method of degeneration, that is, of tracing the pathways and centers of dead cells, is often used in reconstructing the lesions that have been made.

A second major technique used in physiological psychology is that of electrical recording of potential changes in various parts of the nervous system. The galvanic skin response (GSR) is one such recording made on peripheral nervous effects. Recordings made from the central nervous system fall into three main categories: (1) an electroencephalogram (EEG) of the spontaneous fluctuations in potential (“brain waves”), (2) gross action potentials of nerves or of sensory pathways, and (3) microelectrode recordings made from single cells or small groups of cells. The last two types of recording are usually “time locked,” that is, made with reference to some sensory or electrical stimulus applied at a given time for a given duration. [SeeNervous system, article onelectroen cephalography.]

Stimulation methods, a third class of methods, consist of the electrical or chemical stimulation of the brain. In the past, electrical methods have been most prevalent, but recently techniques for chemical stimulation have been improved and are coming into greater use. Either method may be used in exploratory or chronic form. In exploratory form the stimulus is applied at different points in the exposed brain, and the effects are noted. The electrical-stimulation method was first used to map the motor cortex; in recent years it has sometimes been used with conscious human patients to map motor, sensory, and association areas of the cerebral cortex. Chronic stimulation may be achieved by setting in place surgically an implanted electrode (for electrical stimulation) or cannula (for chemical stimulation) and after surgical recovery, using the implant, at will, to stimulate the otherwise normal, intact animal. Electrical stimulation applied in this way may be either aversive or rewarding. Chemical methods of stimulation through implants are chiefly being used to study the structures involved in such physiological drives as hunger, thirst, and sex. [SeeNervous System, article onBrain Stimulation; see alsoDrives.] The fourth general class of physiological methods, namely the hormonal and biochemical methods, consists of any intervention in the biochemical systems of the body. The oldest form of this method is the removal of an endocrine gland, such as the gonads, to determine its effects on behavior. This gland removal may be combined with replacement therapy, in which the hormone normally made by a gland is injected in its absence. Replacement therapy has the advantage of allowing the reversal of hormonal conditions by the experimenter at some later time. In recent years, with advancing knowledge in psychopharmacology and in biochemistry, chemical methods increasingly employ the administration of drugs or of other biochemical substances through the mouth, directly into the blood stream, and sometimes to the brain itself. [SeeDrugs, article onpsychopharmacology; Sexual behavior, article onsexual deviation: psychological aspects.]

Major areas

Physiological psychology concerns the same areas as human and animal experimental psychology: (1) sensory processes, (2) motor functions, (3) motivation, (4) learning, and (5) complex processes, including language, thinking, and social behavior. The amount of information available about each area is progressively smaller in the order mentioned. This comes about partly because techniques for the psychological study of sensory and motor functions are more highly developed and partly because more complex processes are most prominent in higher animals and man, where it is difficult or sometimes impossible to employ the appropriate physiological techniques.

The remainder of this article will summarize the principal conclusions that can be drawn from the field of physiological psychology at the present time. The purpose is to give an over-all picture that will integrate and supplement the several articles in this encyclopedia covering or touching upon specific topics in physiological psychology.

Sensory systems

Elsewhere in this encyclopedia are separate articles covering the various senses. They therefore will not be discussed separately here. Rather we shall be concerned with the general features of sensory function.

Each of the senses responds to a different form of energy: electromagnetic, mechanical, chemical, etc. Whatever the energy of stimulation, however, the first step in the processing of sensory information is a transduction of energy into an electrical form known as the generator potential. This is a graded, fluctuating potential that does not follow the well-known all-or-none law. Rather its magnitude is proportional to the intensity of the impinging stimulus. When the stimulus is a vibration or oscillation, as in hearing, the generator potential also oscillates and reflects rather faithfully the transitory changes in the stimulus. When the stimulus is a steady one, as in continuous stimulation of the eye by light, the generator potential also rises to, and maintains, some steady value.

The transduction process in which the generator potential arises is different in the different senses. In the eye a photochemical event intervenes; light decomposes photosensitive molecules, and this decomposition gives rise to generator potentials. In the ear, pressure changes in the inner ear act on hair cells, which generate a potential. Other senses have not been so carefully studied in this regard, but in each case the intervening event giving rise to the generator potential seems to be either mechanical or chemical.

The generator potential in turn gives rise to the now-familiar nervous impulse. This follows the all-or-none law of either not occurring at all or of appearing at a fixed amplitude. These nervous impulses, or in physiological parlance, spike potentials, propagate inward from the sense organ to the central nervous system and are the sensory messengers. Their number is proportional to the size of the generator potential and hence reflects the intensity of the stimulus.

The identity of different kinds of receptors is maintained fairly well in the sensory pathways but not in any simple fashion. In the eye, for example, there are at least three different kinds of color receptors, each most responsive to a different part of the visible spectrum. Farther along the visual pathways, in the thalamus and cerebral cortex, one can find, using microelectrodes, nerve cells that respond specifically to different parts of the spectrum. At this level, however, there is evidence of an interaction of receptors. Different receptors play upon the same central neuron, some exciting and some inhibiting it, and its response therefore is a complex function of the activities of different receptors. Similar statements can be made for all the senses. Many central neurons respond specifically to certain patterns of stimulation on the periphery.

All sensory systems have a topographical projection. That is to say, they maintain in various degrees the spatial relations of the peripheral receptors. The most precise case of topographical projection is found in the visual system, where there is a point-to-point projection of the retina on the visual cortex. Such a projection distorts the peripheral map, a relatively larger area of the cortex being given over to the highly acute fovea than to the less acute peripheral retina. This kind of distortion is seen in all the senses, but topographical relations are nevertheless maintained.

Generally speaking, spatial and qualitative aspects of sensory experience are mediated at the cortical level, and the intensive aspects of experience are processed subcortically. In higher vertebrates, for example, removal of the visual cortex causes pattern blindness but leaves the animal able to discriminate differences in intensity. Similarly, animals deprived of auditory cortex are deficient in sound localization and in pitch discrimination but are able to respond to the presence or absence of sounds if they are not too weak. Similar examples could be given in the other senses.

To summarize, then, peripheral stimuli impinging on receptors are first transduced into graded generator potentials. These give rise to all-or-none spike potentials which propagate centrally. Many central neurons have specific functions representing different kinds of peripheral stimulation, but they reflect interaction of many neurons playing upon them. All sensory systems maintain a topographical orientation. In general, the cerebral cortex is necessary for responding to the spatial and qualitative aspects of stimulation but not to its intensive aspects. [SeeNervous system, article onstructure and function of the brain.]

Motor functions

Let us turn now to the motor functions. These may be considered, for the present purposes, in three general classes: (1) skilled acts, (2) postural reactions, and (3) emotional reactions. In higher vertebrates the ability to make highly skilled motions, such as the manipulation of objects, depends on the integrity of the cerebral cortex and even more specifically on the motor (precentral) area of the cortex lying just in front of the central fissure. Removal of this area, including some fringe portions of it lying behind the central fissure, causes paralysis.

The maintenance of tone in skeletal muscles, the keeping of one’s balance and upright posture, and certain other specific reactions, such as righting reflexes, are included in the term postural reactions. These depend on a complex system in the brain which includes several parts of the cerebral cortex, principally those lying in front of and behind the motor cortex, several subcortical structures, and the cerebellum of the hindbrain. There are certain specific effects of injury to any one of these structures, but the system also tends to work as a whole, so that the more of it that is intact the better the postural adjustment of the organism.

Emotional reactions depend upon both cortical and subcortical structures of the cerebrum, but the most important ones are subcortical. The cerebral cortex exercises considerable control over the timing and intensity of emotional reactions, but the primary emotional mechanisms are to be found in a complex of centers and pathways known as the limbic system. Of these, three structures are most prominent: the septal area, the amygdala, and the hypothalamus. The hypothalamus seems to be the principal organ of integrating patterns of emotional expression, but it is controlled or modulated by opposing influences from the septum and amygdala. In general, the septum is inhibitory; removing it causes an animal to be hyperemotional. The amygdala, on the other hand, is mostly, though probably not entirely, excitatory; removing it causes docility. [SeeEmotion.]


Turning now to a third area of physiological psychology, that of motivation, we may note that rapid progress has been made in this area in recent years, largely through the use of electrodes and cannulas implanted in the deep structures of the brain. The general picture emerging from this work is as follows: Physiological drives such as hunger, thirst, and sex are based in chemical conditions of the blood. What these conditions are is not always precisely known, but whatever they are, they come to affect behavior by circulating in the blood to the hypothalamus and there affecting certain specific cells and centers. There are, for example, certain cells in the hypothalamus that respond to the female hormone, estrogen, and are responsible for the behavior of, say, a cat in heat. This is demonstrated by bringing animals into heat by applying small quantities of estrogen to the cells of the hypothalamus and then, by carbon 14 tagging of the estrogen, determining that the estrogen has been taken up by certain cells and not by others. Although not all experiments are as dramatic, many lead to the conclusion that motivated behavior is aroused by certain hypothalamic cells responding much like chemical receptors to chemical conditions in the blood.

Within the hypothalamus, motivational centers appear to work in pairs. This statement is well substantiated for hunger and sleep but is not yet so clear for thirst and sex. In hunger a satiety center is found in the ventromedial region of the thalamus, and a hunger center in the ventrolateral region. One is called a satiety center because its removal causes an enormous increase in food intake (hyperphagia); the other, a hunger center, because its removal causes the opposite effect, namely, such a remarkable loss of hunger that animals starve to death unless artificial means of keeping them alive are employed. A thirst center is difficult to distinguish anatomically from the hunger center, for damage to the hunger center causes a primary disturbance of thirst (adipsia), but there are probably different cells in this region subserving hunger and thirst. Substantial increases and decreases in sexual behavior may follow experimental lesions in the hypothalamus, but the arrangement of hypothalamic centers for sexual behavior has not been clearly defined. In any case, fundamental mechanisms for the control of physiological drives are located in the hypothalamus. These are aroused by chemical conditions in the blood, and they are also, of course, affected by inputs from sense organs and from higher cerebral structures, including the cerebral cortex. [SeeDrives; Motivation; Sexual behavior, article onanimal sexual behavior.]

Conditioning and learning

A fourth major area of physiological psychology is the study of the neural mechanisms of conditioning and learning. This area is conveniently divided into three sub-areas: (1) conditioning, (2) discriminative learning, and (3) problem solving and maze learning. [SeeLearning, especially the article onneurophysiological aspects.]

Contrary to Pavlov’s assumption in his early work on conditioning, the cerebral cortex is not necessary for conditioning to take place. Animals that are completely decorticate can be conditioned in the classical sense to make some response to a signal. Difficulty arises, however, when an attempt is made to produce an instrumental response, such as raising of the paw to a signal in order to avoid shock. The difficulty is partly that decortication considerably reduces the motor ability of the animal and partly that the decorticate is more easily aroused emotionally by the noxious shock. If care is taken to keep the animal quiet, by presenting a weak shock and allowing a considerable interval between conditioning trials, even an instrumental response may be conditioned.

Although we are certain that the cerebral cortex is not necessary for conditioning, it is hard to say just what parts of the nervous system are. Although some work has been done on spinal animals, it is doubtful that conditioning can take place at the level of the spinal animal. On the other hand, conditioning has been obtained in decerebrate animals whose brains have been transected at the midbrain level. Hence, it appears that the simple phenomenon of conditioning can occur at the level of the hindbrain.

In recent years there has been considerable interest in the electrical correlates of conditioning. This interest has been pursued by recording the electroencephalogram or other oscillations in brain activity at different sites in the brain during the course of conditioning. It is difficult as yet to draw many conclusions from this work. One result, however, does turn up repeatedly. In the reticular activating system, as well as in other structures related to it, an increase in electrical activity accompanies the early stages of conditioning. As the conditioned response is perfected, however, this activity usually subsides. This electrical correlate appears to reflect attention and arousal. As conditioning trials proceed, the animal becomes more alert and attentive to the conditioning situation. But later, as the conditioned response becomes more “automatic,” such attention wanes and along with it its electrical correlate. [SeeLearning, articles onclassical conditioning, INSTRUMENTAL LEARNING, andAVOIDANCE LEARNING; see alsoAttention.]

Discriminative learning is learning in which the organism learns to make one response to one stimulus and another response (sometimes this is the withholding of response) to another stimulus. Most of the results of research on the neural mechanisms of discriminative learning can be predicted from a knowledge of the sensory mechanisms discussed above. Each sensory system has its area of projection in the cerebral cortex. This projection is concerned primarily with spatial and qualitative aspects of a stimulus. Hence, an animal lacking its visual cortex is unable to learn a visual-pattern discrimination, and one deprived of its auditory cortex is unable to make good sound localizations. In each case, however, the deficit appears to be one of sensory capacity rather than an inability to learn apart from sensory capacity.

The problem becomes more intricate, however, when we turn to intensity discrimination. The capacity to make such a discrimination is not dependent upon the cerebral cortex. Yet animals that have learned a discrimination and are then subjected to removal of the relevant projection area usually lose all memory of the discrimination they have learned. On the other hand, however, they are capable of relearning it in about the same number of trials as they required originally. It is this phenomenon, which has been obtained many times, that led Lashley to propose the principle of equipotentiality, namely, that when one part of a sensory system is injured, other parts of the system have the capacity to take over the function impaired by the injury. This, however, is not a very satisfying explanation, and the matter is still under study. [SeeLearning, article ondiscrimination learning.]

Problem solving and maze learning are in the class that Edward L. Thorndike called trial-and-error learning. Put in a problem box, the animal tries one thing, then another, and finally strikes on the “trick”—which might consist of operating a latch—that solves the problem, say, of obtaining food. Or put in a maze, the subject wanders in and out of blind and correct alleys until it finally comes to the reward.

In general, the ability to learn by trial and error depends on the cerebral cortex. If the problem is very simple, requiring only some gross movement like stepping on a pedal, most of the cortex can be removed without impairing this learning ability. The more complex the problem, however, the more the cerebral cortex is required. In fairly difficult problems, whose solution borders on requiring the use of reasoning, very small cortical lesions may seriously impair problem-solving ability. However, in all cases a distinction must be made between learning and retention. A lesion made after a problem has been learned may seriously impair retention, but if more training trials are given, the subject may learn the solution again. This is another instance of what Lashley called equipotentiality. Also, for fairly complex problems there is not much localization of function; the mass of cortex intact rather than a particular locus is what determines degree of retention or of learning ability. This is what Lashley called mass action.

In making these statements, we must qualify them according to the species we are talking about. The primate brain is more highly organized than the rat’s brain, and there is a correspondingly higher degree of localization in it than in the rat’s brain. In the primate brain, for example, there is a well-defined area of the temporal lobe that is concerned with the learning and retention of visual discriminations. If this area exists in the rat brain, it is not well delineated.

Language and complex processes

A fifth major area of physiological psychology is the study of complex processes, such as language and thinking, and their neural correlates. Although the most interesting of all the areas of physiological psychology, it is the one about which the least is known. This is partly because of the difficulty of studying brain functions in man, in whom these processes are most highly developed, and partly because the processes are inherently difficult to study with any precision. There are, however, certain conclusions that can be drawn at this time. One is that there is generally more localization of function in man and primates than in lower animals, although this localization is by no means precise. More specifically, we find that the prefrontal lobes lying in front of the motor areas are concerned with expressive functions, particularly with those that require planning and doing things in a prescribed order. The posterior cortex is more concerned with receptive functions. In it are the primary sensory projection areas found in lower animals, but also quite massive “association” areas. Many of these areas have either an unknown or a diffuse function, but some are clearly concerned in certain kinds of memory and recognition abilities.

Language, of course, holds a peculiar fascination because it is the most complex of all behavior functions and is uniquely human. For just that reason, however, our knowledge of its physiological mechanisms is limited, being based solely on clinical cases of brain injury. It is fairly well established, however, that the left side of the cerebral cortex is almost always the seat of language functions. Injuries to the right cerebral cortex seldom affect language ability, while those to the left, if of any consequence, almost always do. A large area of the left hemisphere is concerned in language; it extends forward into the frontal lobes and backward into the temporal and parietal lobes. Within this large area there is some localization of different kinds of language functions, but not a great deal. As research proceeds and our methods of analysis become more refined, we should gain a clearer picture of the way the brain coordinates complex functions. [SeeLanguageandMental disorders, article onorganic aspects.]

Clifford T. Morgan

[Directly related are the entriesDrugs, article onpsychopharmacology; Mental disorders, article Onbiological aspects; Nervous system; Senses.Other relevant material may be found inHearing; Pain; Skin senses and kinesthesis; Taste and smell; Vision; and in the biographies ofBroca; Flourens; Lashley.]


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The term human constitution refers to the sum total of the morphological, psychological, physiological, and biochemical characteristics of an individual which are mainly determined by genetic factors but which are influenced in varying degrees by environmental conditions. One of the main objectives of the study of the human constitution is the discovery of significant relationships among these characteristics and between them and pathological and behavioral characteristics. The field of study includes ascertaining the nature of individual variations, their determinants, and the extent to which they are governed by genetic and environmental influences respectively. Those attributes that show marked variability between individuals and relative constancy within the individual are the ones most likely to be useful for research purposes.

Historical perspective

Throughout the ages there has been interest in finding clues to a person’s personality, temperament, behavior, and susceptibility to disease. Aristotle, for example, founded the science of physiognomy, which attempted to relate a person’s mental and moral qualities to his external lineaments. Hippocrates and Galen described specific physical types with characteristic temperamental dispositions and specific susceptibility to different diseases.

In more recent times, Beneke (1881) published data on organ size in various diseases and in relation to various physical types. During the same period, Giovanni, the founder of clinical anthropometry, tried to establish that the cause of the special morbidity of an organ was based on its disproportionate development relative to other parts of the body (1891). Kretschmer (1921) published his classic study Physique and Character, in which he described relationships between different types of physique and predisposition to different psychiatric illnesses. He considered that there is a clear biological affinity between manic-depressive illness and the broad or pyknic type of body build and that schizophrenic patients commonly exhibit the characteristic features of the narrow or leptosomatic physique and certain types of dysplasia, or physiques in which there is uneven growth in different body regions. Kretschmer also extended the scope of his theory to the relationship between physique and normal personality types. He considered that there is a gradation of temperament characteristics from the manic-depressive through the cycloid psychopathological form to the normal cyclothymic personality and, likewise, a gradation of characteristics from schizophrenia through schizoid psychopathology to the normal, well-adjusted schizothyme. He considered that schizoids and schizothymes tend to have leptosomatic, athletic, and dysplastic physiques and that cycloids and cyclothymes tend to have pyknic physiques.

Kretschmer’s work stimulated a great deal of research and, in fact, was responsible for the recrudescence of interest in constitutional psychology, which had, up until then, been relegated to the background by the growth of knowledge in pathology and bacteriology relating to the causation of disease. [See the biography ofKretschmer.]

Major approaches

In recent years there have been considerable advances in the study of constitutional psychology through the development of new techniques and methods of investigation. The following are the main approaches:

Factor analysis and other statistical procedures for elucidating the variables underlying body build; Sheldon’s classification of somatotypes; Lindegard’s method of assessing body build; analysis of tissue components; studies of androgyny; and genetic and growth studies.

From the time that Hippocrates divided physiques into the habitus phthisicus, or narrow type, and the habitus apoplecticus, or broad type, many different systems of classifying physiques have appeared. These are summarized by Rees (1960), who noted that the majority of authors had independently described more or less corresponding physical types with a dichotomy of contrasting, antithetical types as extremes, and with intermediate types in some classifications. The basis of these classifications was not scientific but reflected preconceived ideas about the nature of variations of physique and suppositions based on alleged physiological, dietetic, and developmental characteristics.

The concept of physical types as disparate or mutually exclusive categories has now been replaced by the concept of a continuous variation in body build. The field of constitutional research had been handicapped by the fact that the full extent of the variations in physique in the normal population was not made known and that the various proposed typological classifications were based on unverified hypotheses. What was needed was an inductive method that would ascertain the nature of the variations of physique in the normal population and describe these variations most effectively and economically. Factor analysis, which had proved fruitful in the study of intelligence, provided one such method.

Factor analysis

Factor analysis provided a relatively objective and inductive method of elucidating the variation of physique in the normal population and describing it in an economical and effective way. Factor analysis reduces a large number of variables to a smaller number of categories or factors that can account for the correlations between the original variables. It has a special advantage for the study of the human constitution in that it can account for a representation of human physique which is far more comprehensive than that given by anthropometric measurements alone. [SeeFactor analysis.]

The method of factor analysis may be applied to traits or to persons. The factor analysis of persons provides a method of determining how true an individual is to a particular type and involves the specification of the type in question by a set of representative measurements expressed in standard measure. The correlation between the person’s measurements and those of a standard pattern indicates how nearly he approximates a perfect representative of that type. This method presupposes that the characteristics of the type have already been clearly established; it is, therefore, not used for ascertaining the nature of the variations in human physique that are useful in delineating physical types.

Most factor analyses of physique deal with traits; the steps required for employing factor analysis on physical constitution in this way are as follows: First, a random and representative sample of the normal population is selected and a comprehensive series of anthropometric measurements covering all parts and dimensions of the body is taken on the sample. Each measurement is correlated with all the other measurements for the total group, providing a correlation matrix. One of the primary assumptions in factor analysis is that when a correlation exists between any two variables, they must share a common factor.

The next step is the discovery of the factors accounting for the correlations. The effect of each discovered factor is removed from the matrix before extracting the next factor. This process is repeated until the residual correlations are statistically insignificant. Some factor techniques may extract factors that are independent, that is, factors that are themselves uncorrelated or orthogonal. Other techniques involve matrix rotation, in an attempt to get a better description of groups of correlations and produce correlated or oblique factors.

Factor analysis also indicates which measurements are likely to be most effective for discriminating physical types. Such measurements may be combined to form indexes of body build, either in the form of suitably constructed ratios or in the form of regression equations of weighted measurements.

To illustrate the use of factor methods in analyzing physique, the results obtained by Rees (1950a) for a group of 200 adult men and a group of 200 adult women are presented briefly. Some 18 anthropometric measurements were taken on both groups and were intercorrelated and factor analyzed. For both men and women the correlation coefficients between all physical measurements were positive. A general factor was extracted first and was found to contribute 34 per cent of the variance. The second factor extracted was bipolar, having positive saturations with length measurements and negative saturations with breadth and circumference measurements. These two factors were found in both the male and female groups. This second factor clearly differentiates two extremes: the linear type of physique—length measurements preponderant in relation to breadth and circumference; and the broad type—breadth, width, and circumference measurements preponderant over length.

In the males two measurements, namely, stature and transverse chest diameter, had particularly high loadings on the second factor. These measurements were combined as follows to form the Rees-Eysenck index of body build:

In the female group there were four measurements with high loadings on the second factor: stature, height of the top of the symphysis pubis from the ground, hip circumference, and chest circumference. It was not feasible to construct a simple female index along the lines of the one for men; thus, the Rees index of female body build was devised as a regression equation based on standard measurement units (Rees 1950a):

These indexes have been calculated for large groups of subjects and in all instances there was a unimodal frequency distribution approximating the normal frequency curve. There was no evidence of multimodality or bimodality as there would be if the physical types represented mutually exclusive, disparate categories. What was found was a continuous variation in physique from one extreme to the other, the extremes of the distribution being present only as easily noticeable but infrequently occurring types.

Any such division into physical types, although convenient and sometimes necessary for research, is arbitrary. One standard deviation above and below the mean were considered to be statistically acceptable arbitrary demarcation points dividing the distribution into three classes: (1) leptomorphs, with a preponderance of length -dimensions compared with breadth, width, and circumference; (2) eurymorphs, with large circumference, breadth, and width measurements in comparison to length; (3) mesomorphs, with an intermediate relationship between lateral and circumference dimensions on the one hand and linear measurements on the other. These categories of physique are not intended to convey the impression of disparate types and are, in fact, ranges of body build objectively measured by new indexes of physique and demarcated by statistical criteria for purposes of description and research.

These findings, derived from groups of adult British men and women, are consistent with those of a large number of other researchers using factor methods in groups of different ages, racial composition, and socioeconomic status. Burt (1938), who was the pioneer of the factor analysis of physique, described the results he obtained for groups of British children and adults and found a well-marked general factor, as well as factors accounting for disproportionate growth in length on the one extreme and breadth, thickness, circumference, and weight on the other extreme. A summary of these studies is presented in detail by Rees (1960).

The factors obtained from factor analysis of anthropometric measurements will, of course, depend on the selection and the number of original measurements used. Howells (1952) carried out a factor analysis on physical measurements of university students; the data included a large number of head and face dimensions. There were three limb measurements and three facial-length measurements. Howells extracted a factor for limb and facial length and concluded that the extraction probably depended more on the measurements chosen than on growth patterns. In all, he found seven factors, which he interpreted as relating to general body size, long-bone length, cranial size, brain size, lateral facial cranial development, face length, and ear size. These can be grouped into four size factors, two length factors, and a breadth factor.

Sheldon’s varieties of physique

Sheldon’s system of classifying physique (1940) was based initially on the inspection of standardized photographs of a large number of individuals. He concluded that there are three components in physique: endomorphy, mesomorphy, and ectomorphy. These, he considered, consist of tissues derived from the three germinal layers: the endoderm, the mesoderm, and the ectoderm. Each subject was observed and rated on three 7-point scales, one for each component. For example, a rating of 7-1-1 represents extreme endomorphy, preponderant in breadth and circumference measurements; a 1-7-1 rating represents extreme mesomorphy, with marked bone and muscle developments, broad shoulders, and muscular limbs; a rating of 1—1—7 reflects extreme ectomorphy, characterized by linearity and relatively poor development of breadth, width, and circumference measurements.

Sheldon’s method was an advance over previous typologies, which tended to regard physical types as disparate and mutually exclusive categories. Sheldon’s method has been criticized because of its subjectivity and because of evidence showing that an individual somatotype, contrary to Sheldon’s claim, is not necessarily constant for a particular individual. Changes in a person’s somatotype occur with changes in his diet and with increase in his age.

In spite of its subjectivity, it has been demonstrated that retest reliability of ratings by experienced workers is high. Sheldon’s assumption that his three components are composed of tissues derived from the three primary germinal layers has not been established, and the number of components underlying variations of physique described by Sheldon is now under considerable doubt because a number of workers have demonstrated that the data can be fully explained in terms of two components rather than three.

Humphreys (1957) found that the correlations between endomorphy, mesomorphy, and ectomorphy provided by Sheldon indicate the existence of only two independent (but not necessarily valid) types of physique. Furthermore, Howells (1952), using factor analysis of persons who were markedly dominant in one or another of the three components, found that the factors extracted do not correspond with Sheldon’s three components. He found that ectomorphy and endomorphy are not independent factors but are opposite extremes of a continuum and manifestations of a single factor.

Modifications of Sheldon’s method. Parnell (1958) pointed out some inherent disadvantages in Sheldon’s system, namely, the subjectivity of the method of estimating somatotype dominance, personal objections by subjects to being photographed in the nude, and technical difficulties in obtaining the equipment necessary for carrying out photography for somatotyping. Parnell’s method involves taking measurements of height, weight, bones, muscle, girth, and skinfolds of subcutaneous fat. Parnell uses ratings of fat, muscularity, and linearity in place of Sheldon’s endomorphy, mesomorphy, and ectomorphy (bone development is included in the estimate of muscularity), and an individual is rated according to these three factors. Primary dominance is indicated by the capital letters F, M, L and secondary dominance by the small letters f, m, and I. The disadvantage of this system is the use of fat and muscularity, which can show relatively marked variation in the individual during his lifetime, sometimes within a comparatively short period of time.

Lindegard’s assessment of body build

Linde-gard (1953) concluded from his studies that there are four factors responsible for the variations in body build: length, sturdiness, muscle, and fat. His method involves rating a person’s dimensions on scales representing each of these factors. The length factor is derived from the length of the radius and tibia; the sturdiness factor is derived from the breadth of the femoral condyle, bimal-leolar and bistyloid breadths, and the distance between the nasion and the sella turcica, measured by X-ray cephalometry; the muscle factor is derived from dynamometer readings of hand grip and foot press; and the fat factor is derived from girth and body weight and girth of the extremities.

The length, sturdiness, and muscle factors are determined directly, but the fat factor is deduced by comparing the weight and extremital girths with the skeletal build and muscle factor. The four factors are plotted on a graph in terms of standard deviation.

Lindegard found that length, sturdiness, and muscle factors are interdependent, and he dealt with this by regression techniques, which yield a relative sturdiness factor and a relative muscle factor. The relative sturdiness factor expresses the skeletal sturdiness in relation to the length factor. The relative muscle factor is expressed in terms of the dynamometer readings in relationship to stature.

The weakness of Lindegard’s system is the probable inconstancy of dynamometric recordings in an individual and the possibility that they might be altered within a short space of time by training and exercise and are influenced by age, disease, etc.

Tissue components, androgyny, gynandromorphy

The measurement of the relative development of bone, connective tissue, fat, and muscle is a comparatively recent development and could be a useful complementary method to factorial studies of physique and to Lindegard’s system and Sheldon’s somatotyping method. The usual method is to use standardized X rays of the calf to measure the relative thickness of bone, fat, and muscle. The relative amounts of these factors in the calf have been found to be more or less independent of each other.

The terms androgyny and gynandromorphy refer respectively to the degree of femininity of body build in the male and the degree of masculinity of body build in the female. Two distinct methods have been employed to assess androgyny: subjective procedures, consisting of assessment and rating of general appearance and special features, and objective anthropometric measurements, such as those described by Tanner (1951).

Tanner used the method of discriminant analysis to ascertain the best possible discrimination between males and females with regard to biacromial diameter and bi-iliac diameter. He found that the best index for discriminating the sexes is

Biacromial diameter x 3 — Bi-iliac diameter — 82.

Tanner (1955) considers that androgyny, in contrast to somatotype, is determined by events taking place at adolescence. Androgyny scores have been used recently to study relationships with academic and athletic performance, physical efficiency, and various diseases.

Genetic factors and growth processes

Important morphological characteristics such as body size, body shape, and body composition are a function of growth rates, which, in turn, are determined by genes in interaction with environmental influences. Polymorphism, or natural variability, is a consequence of genetic and physiological reaction to the environment.

Twin studies are useful in ascertaining the relative importance of genetic and environmental factors in determining various bodily dimensions. Dahlberg (1926) compared the variability in anthropometric measurements between nonidentical and identical twins. It was found that 90 per cent of the variability of body length measurements, and slightly less for body breadth, head, and face dimensions, was determined by heredity.

The majority of bodily dimensions, as well as variations in body size and body shape, are distributed along a normal frequency curve. This is in keeping with the hypothesis of multifactorial inheritance of these characteristics.

It has been demonstrated in animals that general body size is largely determined by genetic factors. It is particularly interesting to note that Gregory and Castle (1931) demonstrated that differences in growth, measured by the number of blastomeres as early as 36 hours after fertilization, exist between large and small varieties of rabbits.

Skeletal age, measured by the degree to which ossification centers and epiphyses are developed, has been shown by Reynolds (1943) to be largely genetically determined, with a correlation of .71 in identical twins, a correlation of .28 in siblings, .1 in first cousins, and .01 in unrelated persons. Age at menarche is a convenient measure of the rate of growth. According to Tanner (I960), the age at menarche is closely related to the growth spurt in body measurements and to the maturation of the skeleton. The age at menarche is normally distributed, which suggests that menarcheal age depends upon the combined action of genes at many different loci rather than any single allele. Tanner reports that in identical twins the average difference in months of age at menarche is 2.8, in non-identical twins 12, in sisters 12.9, and in unrelated girls 18.6.

It has been known for many years that girls are physically more mature than boys at all ages from birth until adulthood. The recent discovery of some persons with chromosomal formulas XXY or XO has provided an opportunity of studying genetic factors that influence differential sex growth rates. Persons with an XXY chromosome complement suffer from Klinefelter’s syndrome and in appearance are males but have small, atrophic testicles, abnormally long legs, and narrow shoulders. Those with XO chromosomes suffer from Turner’s syndrome and are apparently females but lack ovaries, are short in stature, and have no development of the secondary sex characteristics at puberty. [SeeSexual behavior, article onsexual deviance: psychological aspects.]

The question arises whether the skeletal maturity of an XXY child would follow that of the male or the female. Tanner (1960) reports an investigation into the ratio of skeletal age to chronological age in children with Klinefelter’s syndrome compared with normal boys. It was found that the ratios failed to differ significantly, but if they were compared with girls, great differences occurred. Thus, XXY follows the course of XY. Similarly, 16 persons with Turner’s syndrome were rated and found to follow the normal pattern for girls. Thus, XY and XXY have the male initial retardation of skeletal development, XO and XX do not. The inference is clear that this retardation in males is due to genes located on the Y chromosome.

It is clear that individual differences in adult physique must come about through differential local and general growth rates during childhood.

Tanner (1960) points out that there is much evidence to show that the child’s measurements at birth reflect almost entirely the action of the uterine environment and are thus dependent on maternal genotype and maternal environmental factors only. The genotype of the child is practically without effect; it is only subsequently that the child’s genes exert their action and become a basis for predicting the child’s adult status and that the child’s resemblance to his genetic parents becomes increasingly marked.

Personality and physique

It will be convenient to consider studies relating personality and physique according to the particular system used for classifying body build.

Kretschmer’s typology

Kibler (1925), utilizing questionnaires, was able to confirm an association between leptosomatic body build and schizothymic temperament, on the one hand, and pyknic body build and cyclothymic temperament, on the other. However, Pillsbury (1939), using similar methods, found no evidence to support Kretschmer’s theory.

A variety of psychological attributes have also been studied in relationship to Kretschmer’s physical types. Enke (1928), for example, found that persons of pyknic physique were more easily distracted in reaction-time experiments and were poorer in tachistoscopic perception of nonsense syllables than were those of leptosomatic physique. Pyknics tended to respond predominantly to color in tachistoscopic experiments and also tended to react to colors on the Rorschach test.

Lindberg (1938) found that pyknic body build was associated with a greater tendency to color reaction and leptosomatic body build with a greater reaction to form. Keehn (1953), however, has thrown doubt on the interpretation of the tests used as measures of color-form reactivity. According to Misiak and Pickford (1944), leptosomes are more persevering at tasks and have a lower tendency to perseverate responses than pyknics. Smith and Boyarsky (1943) found that leptosomes had a higher tempo, as measured by their tapping rate, and quicker reaction time than pyknics. In a variety of tests, other workers (such as Klineberg, Asch, & Block 1934) found no significant differences between leptosomes and pyknics.

Factor analyses

Burt (1938), in a study of children, found correlations between stoutness of build and cheerful emotions and between thinness of body build and inhibited and depressive tendencies. Rees and Eysenck (1945) and Rees (1950a; 1950b; 1950c), in studies of adults of both sexes, found that leptomorphs have a greater tendency to introversion and a higher tendency to somatic manifestations of emotional tension and autonomic dysfunction, whereas eurymorphs had a greater tendency to extroversion and a greater tendency to hysterical symptoms.

Sanford and his associates (1943) obtained similar results, finding the tall, narrow type of physique to be associated with autonomic dysfunction and manifestations indicative of dysthymia. The wide, heavy type correlated negatively with autonomic dysfunction and positively with secure feelings and lively self-expression.

Sheldon’s somatotypes

Sheldon (1942) postulated three components of personality: viscero-tonia, somatotonia, and cerebrotonia. Viscerotonia is characterized by relative love of comfort, pleasure in digestion, need for affection and approval, and the need of company when in trouble. Somatotonia is characterized by an assertive posture, need for exercise, directness of manner, unrestrained voice, and a need for action in trouble. Cerebrotonia is shown by restrained posture, quick reaction, inhibited social reactions, vocal restraint, and need of solitude when in trouble.

In a group of 200 university men between 17 and 31 years of age, Sheldon (1942) found high positive correlations between the components of physique and the components of temperament: between endomorphy and viscerotonia, the correlation coefficient was .79; between mesomorphy and somatotonia, .82; and between ectomorphy and cerebrotonia, .83.

Humphreys (1957) criticized Sheldon’s methods and stated that the evidence provided by Sheldon supported not more than two independent (but not necessarily valid) types of temperament. Child and Sheldon (1941) reported only low correlations between somatotype and various other psychological attributes. Tanner (1951) found little to support Sheldon’s claims for high correlations between somatotype and temperament.

Parnell (1958), in a study of a group of 7-year-old children, found that fat children had fewer handicaps in the first seven years, were able to express feelings easily, and were confident and sociable. Muscular children were relatively free from anxiety shyness. Linear children were oversensitive, shy, and had greater difficulty in communicating their thoughts and feelings to people around them; they had signs of emotional unrest such as nightmares, panics, temper tantrums, and nail biting and also tended to be meticulous and conscientious and to exhibit high standards.

Studies based on Lindegard’s method

Linde-gard and Nyman (1956) studied a group of 320 men whose physiques were rated according to Lindegard’s method (1953). It was found, for example, that the muscle factor was correlated with expansivity and self-confidence versus unobtrusiveness; the more muscular person is more expansive and confident, the less muscular person is emotionally cool and sophisticated.

Wretmark (1953) found that stability (identified as emotional warmth, rather than emotional coldness, together with sophistication and proficiency of motor activity) was the only attribute correlated with body build. He found that sub-stable individuals were relatively wide and heavy and that extraordinarily stable individuals tended to be narrow in body build.

Physical attributes and intelligence

For many years research has been carried out to discover whether some physical attribute would provide some clue to a person’s intellectual ability. This has been a matter of interest to educators and psychologists who aim to provide objective aids for assessing intelligence.

Rees (1960), reviewing other literature as well as his own investigations, concluded that the evidence indicated no relation between absolute anthropometric measurements and intelligence level.

When the relationship between body type or body build and intelligence is considered, Rees (1960) found that there was a slight tendency for leptomorphs to be higher in intelligence than eurymorphs.

Parnell (1958) investigated the intelligence level of a group of 7-year-old children and found that children with linear physiques were best in reading ability. At the age of 11, linear children did better than general expectation on the entrance examination for British grammar schools. Studies by Parnell (1958) of university students again provided evidence that linear men tend to do better. On the other hand, the best order of performance at work and at games was achieved by Mf men, that is, those in whom muscle is the dominant factor and fat the secondary factor.

Rees’s conclusion (1960) still holds: the correlation between physique and intelligence is so low that a knowledge of a person’s physical status will be of no value in the prediction of intelligence in the individual case.

Body size

The Rees index of body size, represented by the product of stature and transverse chest diameter, was obtained for a sample of 1,100 military personnel admitted to the Mill Hill Emergency Neurosis Centre; the frequency distribution was normal and was arbitrarily divided at points one standard deviation above and below the mean into three groups: microsomatics, mesosomatics, and macrosomatics.

A detailed analysis of psychological attributes in these groups showed, for example, that neurotics with large body size tend to be more active and to have a more stable personality, better musculature, a higher intellectual level, and a better prognosis for return to military duties. The microsomatic group tend to be of inadequate personality makeup: i.e., they have a higher incidence of weak, dependent, anxious, and hypochondriacal traits of personality and narrow interests and hobbies.

It is interesting to note that the psychological correlates of body size differ from those associated with physical type. Whereas the extremes of body type, the eurymorph and the leptomorph, are associated respectively with hysterical and anxiety reactions, there were no significant relations between these reactions and body size.

Body disproportion

Seltzer (1946) paid particular attention to disproportionate development of the body, which he defined as values of the index derived from anthropometric measurements which are markedly divergent from the mean, usually in one direction. One such disproportion might be a combination of wide shoulders and thin legs; another, broad hips relative to shoulder width. The term “disproportion“must not be confused with the term “dysplasia.“It does not carry any stigma of abnormality; it represents deviations within the normal range of variation.

Seltzer found that individuals, and particularly linear individuals, with unstable autonomic functioning showed a greater tendency to bodily disproportion. He found excesses of one or more bodily disproportion to be associated with the following characteristics: unstable autonomic functions, mood fluctuations, personal instability, inability to adjust, sensitivity, meticulousness, self-consciousness, and introspection. There were significant deficiencies associated with those traits indicative of stability and ease of making adjustment. It was found that disproportions were commoner in marked ectomorphs and least common in marked endomorphs.


Using Turner’s androgyny scale, Rees (I960) found that a group of 200 soldiers suffering from effort syndrome (neurocirculatory asthenia), a disorder in which breathlessness and various autonomic symptoms accompany exercise, showed more marked feminine attributes in body build than normal, healthy soldiers.

Coppen (1958), using the same index, found that patients who developed toxemia in pregnancy had a higher incidence of masculine features in body build than those who did not.

Parnell (1954) compared the relationship between the relative incidence of masculine and feminine physical traits and academic and athletic performance in men and found that academic distinction was associated with a significant trend toward feminine traits and that athletes, as would be expected, showed a higher incidence of strong masculine traits.

Lindegard (1956), using a scale based on a regression equation using biacromial and bi-iliac measurements, found no significant relationships with personality variables.

Seltzer and Brouha (1943) found that excellent degrees of physical fitness could be achieved only by persons with a strong masculine component in their physique and that individuals weak in masculinity tended to have poor effort tolerance, that is, the ability to undertake effort without suffering unduly from distress.

Physique and mental illness


Rees and Eysenck (1945) studied a group of 400 soldiers admitted to Mill Hill during World War n. Rees extended this study to 1,000 soldiers (1960) and to 400 women serving in the armed forces who developed neurotic illness (1950a; 1950b; 1950c).

Using the Rees-Eysenck index of body build, it was found that leptomorphic individuals of both sexes tend to have dysthymic symptoms, whereas eurymorphs tend toward hysterical characteristics and symptoms.

Parnell (1958) in an analysis of a survey of 2,000 hospitalized psychiatric patients suggests that if breakdown occurs in Lf types it more often occurs before the age of 25. Male patients under age 25 with a diagnosis of depression, anxiety state, psychopathy, or suicidal tendency were found to be generally of the Lf physique. Among schizophrenics under age 25, the males tended to be most commonly of Lf type, and next most commonly Lm. Among female schizophrenics the most frequent type was Fl. Lm types of both sexes are more disposed to breakdown from 25 to 35 years of age. Ml types of both sexes are more predisposed to breakdown from 35 years of age onward. Paranoid schizophrenia and paranoid illnesses are their commonest examples of thought disorders. Depression is the major affective illness in both sexes.

Mf types were the most stable in both sexes. When they become mentally ill they are usually over 30 years of age. Thought disorder usually takes the form of a paranoid illness, but an affective disorder with depression is the commoner form of illness. [SeeNeurosis.]

Manic-depressive illness

In a review of the literature and his own studies, Rees (1960) concluded that there is some correlation between pyknic habitus and manic-depressive psychosis, but the correlation is not, by any means, as great as suggested by Kretschmer. Rees (1960) also pointed out that the age factor accounts for part of this correlation but does not completely invalidate Kretschmer’s theory. [SeeDepressive disorders.]


Rees (1943) carried out a detailed anthropometric investigation on a sample of schizophrenics as well as on a control group of normal men of similar age distribution. He found that schizophrenic patients are significantly smaller in stature, chest circumference, hip circumference, biacromial diameter, supersternal height, and sym-physis height. Body build indexes showed that they are significantly more leptosomatic than the normal group.

There is some evidence of a relation between type of physique and specific form of schizophrenia. Connolly (1939) reported that paranoid schizophrenics are of larger body size and more pyknic in physique than other types of schizophrenic patients. Rees (1960), reviewing the literature, states that a number of authors have suggested that schizophrenics with a leptomorphic body build tend to have an earlier age of onset and show a greater degree of withdrawal, apathy, and thought disorder, whereas schizophrenics of eurymorphic body build tend to have a later age of onset, better preservation of personality, and better affective relations with the environment.

There is also some evidence to suggest that physique may have some bearing on the course and prognosis of a schizophrenic illness. Kallman (1953) found that high linearity and low athletic components in physique are associated with a tendency to marked deterioration during the course of the schizophrenic illness, whereas patients with high athletic and low linear components do not show such deterioration; these last are usually paranoid schizophrenics.

Kallman (1953) found that monozygotic twins who both suffer from schizophrenia and are of similar body build tend to have similar types of schizophrenic illness with onset at the same age and similar outcomes. When there are differences in physique, there are also differences in the age of onset as well as in the severity of schizophrenic symptoms. In monozygotic twins discordant with regard to schizophrenia, the twin remaining completely free from schizophrenia had significantly greater physical strength and was higher in body weight from early childhood. [SeeMental disorders, article ongenetic aspects.]

Parnell (1958) found that the Lf type has the longest hospital stay and also tends to onset before the age of 25, whereas the Mf type stays in the hospital the shortest time and least often succumbs to schizophrenia. [SeeSchizophrenia.]

Psychosomatic disorders

Investigations relating physique to physical and psychosomatic disorders have generally been handicapped by methodological difficulties, mainly the absence of appropriate control groups and failure to control for age. However, some of the better studies are discussed here.

Peptic ulcer, asthma, gall bladder disease

Wret-mark (1953), in a carefully planned and adequately controlled study, found that duodenal ulcer patients were more linear in physique than a control group and that the more linear the body build, the worse was the prognosis.

Brouwer (1957) was unable either to replicate the findings of Draper et al. (1944), who claimed that mesomorphic body build is characteristic of ulcer patients, or to support the views of Sheldon (1940) that endomorphic mesomorphy characterizes them. Brouwer found, in agreement with Wret-mark, that duodenal ulcer patients are more inclined to leptosomatic body build but do not differ significantly in ectomorphy, as measured by Sheldon’s system, from healthy male controls or from groups of male patients with other disorders.

Draper et al. (1944) considered that gall bladder disease is associated with a broad, stocky type of physique. Sheldon (1940) also found that gall bladder patients are mesomorphic-endomorphic. Age was not adequately controlled and Brouwer (1957), using Sheldon’s method, found a preponderance of endomorphy in female gallstone patients, though not significantly more than in the comparable healthy female control group.

Rees (1957) and Brouwer (1957), using quite different methods, found that asthma is associated with a variety of somatotypes and patients do not differ significantly in physique from the normal population.

Cardiovascular disorders

Rees (1963) reported that military patients at Mill Hill suffering from effort syndrome, cardiac neurosis, and neurocirculatory asthenia were significantly more leptomor-phic in body build than normal groups. In a comparison of effort syndrome patients, Rees (1944) found that the majority of leptomorphic patients had suffered from effort intolerance and autonomic dysfunction from an early age and had long-standing personality traits of timidity, anxiety, and neuroticism. Eurymorphic patients, on the other hand, were characterized by short duration of illness, which tended to be precipitated by a great number of exogenous factors, such as severe environmental stress and severe enemy action. In other words, leptomorphic effort syndrome patients exhibited a predominance of constitutional factors, whereas eurymorphic effort syndrome patients had only recently shown effort intolerance, usually brought on by extrinsic factors such as traumatic experiences and febrile illness.

Gertler, Garn, and Levine (1951) showed that endomorphs have a higher level of blood cholesterol than ectomorphs, both in the normal population and among patients suffering from coronary disease. [SeePsychosomatic illness.]

Delinquency and criminality

Glueck and Glueck (1950), in a study of 500 delinquent boys ranging in age from 11 to 18 years, found that in comparison to the normal control group, the delinquents were more mesomorphic and less ectomorphic.

Epps and Parnell (1952) studied a group of 177 women undergoing Borstal training and compared them with a group of 123 university women similar in age distribution. They found that the delinquents were heavier in body build, more muscular, and had more fat.

These results are in good agreement with the Rees-Eysenck findings of a correlation between extroversion and eurymorphic body build and Ey-senck’s theory linking extroversion with psychopathy and criminality (Eysenck 1960).

During recent times, the study of the human constitution has advanced significantly as a result of the introduction of new mathematical techniques and improved methods of recording and measuring constitutional attributes. This has led to the discovery of efficient and valid methods of assessing various aspects of physique.

The relationships between physical attributes and personality, health, disease, and abnormality of behavior may prove to have a genetic basis, with the genes responsible for physical attributes influencing the manifestation of the genetic determinant of personality, psychiatric, physical, and psychosomatic disorders.

One of the most urgent needs in this field is for longitudinal studies of size and form combined with genetic, biochemical, and endocrine studies.

W. L. L. Rees

[Other relevant material may be found inEugenics; Genetics; Mental disorders, articles onbiological aspects, GENETIC ASPECTS, ORGANIC ASPECTS; Physical Anthropology; Radiation.]


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Brouwer, D. 1957 Somatotypes and Psychosomatic Diseases. Journal of Psychosomatic Research 2:23-34.

Burt, Cyril 1938 The Analysis of Temperament. British Journal of Medical Psychology 17:158-188.

Child, Irvin L.; and Sheldon, William H. 1941 The Correlation Between Components of Physique and Scores on Certain Psychological Tests. Character and Personality 10:23-34.

Connolly, Cornelius J. 1939 Physique in Relation to Psychosis. Catholic University of America, Studies in Psychology and Psychiatry, Vol. 4, No. 5. Baltimore: Williams & Wilkins.

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Epps, Phyllis; and Parnell, R. W. 1952 Physique and Temperament of Women Delinquents Compared With Women Undergraduates. British Journal of Medical Psychology 25:249-255.

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Gertler, Menard M.; Garn, Stanley M.; and Levine, Samuel A. 1951 Serum Uric Acid in Relation to Age and Physique in Health and in Coronary Heart Disease. Annals of Internal Medicine 34:1421-1431.

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Gregory, Paul W.; and Castle, William E. 1931 Further Studies on the Embryological Basis of Size Inheritance in the Rabbit. Journal of Experimental Zoology 59:199-211.

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Kallman, Franz 1953 Heredity in Health and Mental Disorder. New York: Norton.

Keehn, J. D. 1953 An Experimental Investigation Into the Validity of the Use of Attitude to Colour and Form in the Assessment of Personality. Ph.D. dissertation, Univ. of London.

Kibler, M. 1925 Experimentalpsychologie: Beitrag zur Typenforschung. Zeitschrift fur die gesamte Neurologie und Psychiatrie 98:524-544.

Klineberg, Otto; Asch, Solomon E.; and Block, Helen 1934 An Experimental Study of Constitutional Types. Genetic Psychological Monographs 16:145-221.

Kretschmer, Ernst (1921) 1936 Physique and Character: An Investigation of the Nature of Constitution and the Theory of Temperament. London: Routledge. -* First published in German.

Lindberg, Bengt J. 1938 Experimental Studies of Colour and Non-colour Attitude in School Children and Adults. Acta psychiatrica et neurologica scandi-navica, Supplement No. 16. Copenhagen: Munksgaard.

Lindegard, Bengt 1953 Variations in Human Body Build: A Somatometric and X-ray Cephalometric Investigation on Scandinavian Adults. Acta psychiatric^ et neurologica scandinavica, Supplement No. 86. Copenhagen: Munksgaard.

Lindegard, Bengt (editor) 1956 Body-build, Body-function, and Personality: Medical Anthropological Investigations on 320 Swedish 20-year-old Healthy Army Men. Lund (Sweden): Gleerup.

Lindegard, Bengt; and Nyman, G. Eberhard 1956 Interrelations Between Psychologic, Somatologic and Endocrine Dimensions. Lund (Sweden): Gleerup.

Misiak, Henryk; and Pickford, R. W. 1944 Physique and Perseveration. Nature 153:622 only.

Parnell, R. W. 1954 Somatotyping by Physical Anthropometry. American Journal of Physical Anthropology New Series 12:209-240.

Parnell, R. W. 1958 Behaviour and Physique. London: Arnold; Baltimore: Williams & Wilkins.

Pillsbury, W. B. 1939 Body Form and Introversion-Extroversion. Journal of Abnormal and Social Psychology 34:400-401.

Rees, W. L. L. 1943 Physique in Relation to Effort Syndrome, Neurotic and Psychotic Types. M.D. thesis, Univ. of Wales.

Rees, W. L. L. 1944 Physical Constitution, Neurosis and Psychosis. Royal Society of Medicine, Proceedings 37:635-638.

Rees, W. L. L. 1950a A Factorial Study of Physical Constitution in Women. Journal of Mental Science 96:620-632.

Rees, W. L. L. 1950& Body Build, Personality and Neurosis in Women. Journal of Mental Science 96:426-434.

Rees, W. L. L. 1950c Body Size, Personality and Neurosis. Journal of Mental Science 96:168-180.

Rees, W. L. L. 1957 Physical Characteristics of the Schizophrenic Patient. Pages 1–14 in Derek Richter (editor), Schizophrenia: Somatic Aspects. Oxford: Pergamon.

Rees, W. L. L. (1960) 1961 Constitutional Factors and Abnormal Behaviour. Pages 344–392 in Hans J. Eysenck (editor), Handbook of Abnormal Psychology: An Experimental Approach. London: Pitman; New York: Basic Books.

Rees, W. L. L. 1963 An Appraisal of the Concept of Cardiac Neurosis. Acta psychotherapeutica et psycho-somatica 11:242-252.

Rees, W. L. L.; and Eysenck, Hans J. 1945 A Factorial Study of Some Morphological and Psychological Aspects of Human Constitution. Journal of Mental Science 91:8-21.

Reynolds, Earle L. 1943 Degree of Kinship and Pattern of Ossification. American Journal of Physical Anthropology New Series 1:405-416.

Sanford, R. Nevitt et al. 1943 Physique, Personality and Scholarship: A Cooperative Study of School Children. Society for Research in Child Development, Monographs 8, no. 34.

Seltzer, Carl C. 1946 Body Disproportions and Dominant Personality Traits. Psychosomatic Medicine 8: 75-97.

Seltzer, Carl C.; and Brouha, Lucien 1943 The “Masculine” Component and Physical Fitness. American Journal of Physical Anthropology New Series 1:95-104.

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Sheldon, William H. 1942 The Varieties of Temperament: A Psychology of Constitutional Differences. New York: Harper.

Smith, H. C; and Boyarsky, S. 1943 Relationship Between Physique and Simple Reaction Time. Character and Personality 12:46-53.

Tanner, James M. 1951 Current Advances in the Study of Physique: Photogrammetric Anthropometry and an Androgyny Scale. Lancet [1951] no. 1:574-579.

Tanner, James M. 1955 Growth at Adolescence. Springfield, 111.: Thomas.

Tanner, James M. 1960 Genetics of Human Growth. Volume 3, pages 43–57 in Symposia of the Society for the Study of Human Biology, Human Growth. Edited by James M. Tanner. Oxford: Pergamon.

Wretmark, Gerdt 1953 The Peptic Ulcer Individual: A Study in Heredity, Physique, and Personality. Acta psychiatrica et neurologica scandinavica, Supplement No. 84. Copenhagen: Munksgaard.


Existentialism is a broad cultural movement showing itself in almost all aspects of contemporary culture: literature, art, philosophy, theology. We can best see the meaning of this development in psychology and psychiatry by first defining the term.

“Existence” comes from the Latin root ex-sistere, which means literally “to stand out,” “to emerge.” Every being, whether a tree or dog or man, “stands out” from being in general to the extent that it has individual existence. But the human being is characterized by his capacity to be aware of the fact that he stands out; that is to say, I can be conscious of the facts that I am this particular man (middlewestern American) who stands at this particular point in history (mid-twentieth century), who exists in a given physical and social world (New York City), who has the intention at this moment of writing this article, and so on. The term our German colleagues use for the human individual is Dasein, composed of Sein, “being,” plus da, “there.” Man’s capacity to become aware of his existence—which distinguishes him as a human being, separate from the rest of nature— implies that he can respond to the facts of his own existence and thus exercise some responsibility for it.

Existence versus essence

In Western thought there are traditionally two philosophic concepts-— “existence” and “essence”—customarily used in contrast to each other. “Essences” refer to discrete entities which can be separated out and formulated, such as Plato’s “ideas” or Hegel’s panrational-istic concepts. In science, essences have come to refer to attributes such as weight, density, color, or in the study of the human being to neurological patterns, reflexes, drives, and so on. By and large, Western thought since the Renaissance has been concerned with essences; traditional science, assuming an essentialist metaphysics, has sought to discover these substances and discrete relationships. The existential psychologists and psychiatrists hold, in contrast, that if we try to understand man as a bundle of discrete drives or a composite of reflex patterns, we may end up with brilliant generalizations but we have lost the man to whom these things happen, the human being we set out to understand in the first place. They are obviously not against the study of dynamisms, neurological and chemical relationships, and patterns of behavior as such. But they hold that these cannot be understood in any given individual—such as a patient in therapy—except in the context of the overarching fact that here is a person who exists, who is; and how this person relates to his existence at this given moment is essential to the meaning of a given pattern of behavior. The existential approach is thus dynamic in the fundamental sense that it takes the person always as emerging, always in process of becoming. The term “being,” indeed, is not a static noun but a verb form.

Thus the existentialist view of science is close to that of the modern physicists Niels Bohr and Werner K. Heisenberg, who insist that the Coper-nican separation of subjective man from objective nature is no longer tenable and that the ideal of a natural science which is completely objective is an illusion. Also it is to be noted that the contemporary existential emphasis on being is, in one sense, a rediscovery in the West of emphases which Eastern thought has held for centuries but which have been lost in Western overrationalistic and objectivistic concerns since the Renaissance.


Existential psychology has many illustrious progenitors in Western history, of whom we shall mention only three. Socrates, whom Kierkegaard later took as his model, is the prototype of the existentialist in his method of dialogue and his belief that truth is discovered through rigorous, inward self-examination. Augustine is prominent in this heritage in his concern with will and with psychological time. Pascal, a distinguished scientist who saw clearly the limits of natural science for understanding man, emphasized the human being’s affective grasp of truth: “The heart has reasons which the reason knows not of.”

Søren Kierkegaard

Modern existential psychology took its specific form a hundred years ago in Kierkegaard’s passionate attack on Hegel, in whose philosophy, as in other aspects of nineteenth-century culture, essentialism came to its peak. Kierkegaard proclaimed that Hegel’s identification of reality with abstract concepts was trickery and that it seduced men away from their central concern, which was their own understanding and their own decisive actions. Kierkegaard and the existentialists following him (Schopenhauer, Marx, Dilthey, and particularly Nietzsche) fought against the rationalists and idealists who would see man only as subject. But even more strongly they attacked the opposite tendency which was emerging in the nineteenth century to become dominant in the twentieth—namely, the vast pressures to treat man as an object to be calculated, manipulated, and controlled. They saw this trend developing in the application of science to man, and they feared this would sap man’s capacity for decision and individual responsibility. The trend was also present in the growing industrialism and capitalism, where it was attacked by Marx in his early existential statements asserting that the money economy would dehumanize man. The distinctive quality of revolt which characterizes existentialists arises from their common protest against these tendencies toward the objectification of man.

William James

The American psychologist William James was a participant in the existential development; he came back from Europe in the latter part of the nineteenth century protesting against Hegelian rationalism just as Kierkegaard had protested half a century earlier. James’s existential elements include, first, his passionate emphasis on the immediacy of experience. Second, he emphasized ivill and decision; he held that commitment is a prerequisite to the discovery of truth. Third, like Kierkegaard, he distrusted thought separated from action. James’s epistemology has striking similarities to that of Nietzsche in the first part of the Will to Power, where Nietzsche held that truth is the way a biological group actualizes itself. Finally, James’s devotion to social and humanistic values as the overarching context, the “enveloping wider order,” in which natural science plays only one part, makes him similar to the existentialists; he was thus able to bring art and religion into his psychological thought without sacrificing his scientific integrity. James was also, of course, in the natural science tradition, and it is unfortunate that, although his natural science orientation was followed, these broader emphases were ignored or treated with contempt until recently. [See the biography ofJames.]

Sigmund Freud

Freudian psychoanalysis is also, on one side, an expression of what we have broadly designated as the existential development. Freud stands in the line of those explorers of human nature of the nineteenth century—including Kierkegaard, Nietzsche, Schopenhauer—who rediscovered the significance of the irrational, dynamic, “unconscious” elements in personality which had been repressed by the essentialistic presuppositions of Western thinking since the Renaissance. Freud sought to bring the irrational springs of human behavior back into the accepted area of scientific investigation. At the same time, Freud saw himself as an enthusiastic champion of natural science, his goal being to make the irrational elements explicable in terms of the mechanistic Newtonian model in nineteenth-century physics and biology. The existentialists radically disagree with this model of man. In their famous discussions, Bins-wanger (1956) endeavored to show his friend Freud that the latter’s determinism was a metaphysical assumption and needed to be analyzed like any other assumption. But while Freud held resolutely to his determinism in his theoretical model of the mind, in his therapeutic practice he inconsistently remained to a great extent existential. [See the biography ofFreud.]

Contemporary contributions

The existential approach sprang up among men of diverse views in various parts of Europe beginning in the early part of the twentieth century. Eugene Minkowski in Paris, Erwin Straus in Germany and later in the United States, and V. E. von Gebsattel in Germany represent chiefly the first, or phenomenological, phase of this development. The psychiatrist Karl Jaspers, who was later to become a leading German philosopher, wrote a textbook on psychopathology in which he presented a phenomenological analysis of the different kinds of pathology. The book went through many editions and widely influenced psychiatry and research on the Continent; it is now available in English (Jaspers 1913). The second phase, which is more specifically existential, is represented by Ludwig Binswanger, A. Storch, Medard Boss, Gustav Bally, and Roland Kuhn in Switzerland, F. J. Buytendijk and J. H. Van den Berg in the Netherlands, and others.

The fact that this development emerged spontaneously—some of these existential thinkers often scarcely knowing about the remarkably similar work of their colleagues—and the fact that it owes its creation to diverse psychiatrists and psychologists rather than to any one leader, argue that it is a response to a widespread need in our time. The variety of schools can be seen when we note that Minkowski and Straus, for example, were psychiatrists and neurologists, not psychoanalysts; von Gebsattel, Boss, and Bally were Freudian analysts; Binswanger, although remaining in Switzerland, became a member of the Vienna Psychoanalytic Society at Freud’s recommendation when the Zurich group split off from the international group; other existential therapists had also been under the influence of Carl G. Jung.

All of these men shared grave doubts about the theory of man assumed in contemporary psychiatry and psychology, and specifically in psychoanalysis. They had become disquieted over the fact that although they were effecting cures by the techniques they had learned, they could not, as long as they confined themselves to the generally accepted assumptions, arrive at any clear understanding of why or why not these cures occurred. They were unwilling to postulate unverifiable agents such as “libido,” or “censor,” and they asked trenchant questions about what it really means when one says a patient “projects” or “transfers” something to someone else. These explanatory devices, they argued, as often as not actually cover up rather than reveal precisely the empirical data in the patient we wish to understand. They shared the belief that the serious difficulties in the accepted theories of man, including psychoanalysis, would not only gravely limit research in the long run but would also seriously hamper the effectiveness and development of therapeutic techniques.

These psychologists and psychiatrists were also concerned with events prior to the observed patterns of behavior; they asked questions about how particular kinds of behavior are made possible in the patient’s experience. Thus their approach was chiefly concerned not with types of pathology but with norms and structures of being human; the patient’s pathology is a distortion of these. They used psychological terms with an ontological meaning. Kierkegaard held that anxiety is ontological in that it is a constitutive element for the self; a person never actualizes a potentiality without going through what Kierkegaard called the “intermediate determinant” of anxiety (1844). Similarly, Tillich described anxiety as the state of the struggle of “being with non-being” (1952). Nietzsche’s “will” is ontological in that it is necessary for the individual’s self-actualization. Tillich also made “courage” ontological in his trenchant phrase “the courage to be.”

In their therapy, the existential psychologists and psychiatrists also asked such prior questions. Transference, they agreed, is one of Freud’s greatest discoveries, but it can be understood only on the basis of the prior norm of encounter, of which transference is a distortion. As the existentialists describe it, encounter includes not only sexual elements (eros) but such normal elements as mutual esteem and concern between persons (agape) and realistic friendliness (philia). Likewise, Freud’s concepts of resistance and repression refer to observable behavior, but they can be understood only as distortions of the patient’s freedom, that is, of his capacity to actualize some awareness or experience, a freedom which assumedly arouses too much anxiety for the patient to face at the moment.

Admittedly, these ontological questions sound alien to most American psychological thinking, accustomed as it is to “essentialist” behavioristic presuppositions. But research is now going on, to which we shall refer below, which not only may make a bridge to various forms of psychology, but which can bring new and significant empirical data to bear upon our psychology.

Central theoretical orientations

Prior to presenting concepts, it is valuable to see the place of existential psychology in relation to psychology as a whole. Van Kaam (1966) distinguishes between “differential psychologies,” whose concern is the observation and explanation of isolated behavioral processes and functions, and “comprehensive psychologies,” whose aim is the full understanding of human behavior as a whole and in terms of its uniquely human characteristics. Most psychologies have been differential psychologies and have not been integrated into a total image of man. Existential psychology is a comprehensive psychology whose aim is an integration of the observations of differential psychologies into an explanatory theory about human behavior in its lived intentional entirety.

Existential psychologists and psychiatrists share several basic theoretical orientations. First, they deny the subject-object dichotomy that has been dominant in Western thought since Descartes. They emphasize, in contrast, that man exists as subject and object at the same time. May (1966a) holds that a dialectical relationship between subjective and objective factors occurs in every human action and that in this relationship lie the sources of human freedom and creativity. Every act of consciousness is consciousness of something; that is, it has its objective as well as its subjective pole. Consciousness is an active process; the man who is doing the experiencing and the objective world which is the object of consciousness can never be separated.

Second, these psychologists and psychiatrists share a method of scientific investigation—phenomenology—which undercuts the usual objectification in traditional science, employing an unbiased approach.

As Straus points out in his Phenomenological Psychology, science takes for granted precisely what a true psychology must focus upon, namely, our capacities to see, to observe, and to describe. The task of the phenomenologist is less to examine the things observed and more to reflect upon the situation of the observer. The structure and constitution of everyday life (the Lebenswelt) becomes the object of examination because it is this that makes possible the very acts of seeing, observing, and describing, and that gives them their uniquely human qualities. It can be questioned whether phenomenology in psychology and psychiatry is “absolutely” unbiased. For the mere act of listening to a patient in therapy or to a subject in an experiment presupposes some concepts and symbols by which we listen. Nevertheless, the experience of many psychotherapists is that the phenomenological method represents a radical “breakthrough” as a method for understanding the human being. It raises “participant observation,” to use Sullivan’s phrase, to a broader dimension and gives it a structural base as an epistemology.

A third concept, “being-in-the-world,” is hyphenated to indicate again that the being and its world cannot be separated. On the human level world is defined as the meaningful structure of events in which the human being experiences himself; self implies world, and world self, and one is not possible without the other. Furthermore, three modes of world are distinguished. Umwelt, literally the “around world,” is what is customarily called environment, the “natural world.” Mitwelt, literally the “with-world,” is the world of one’s relationships with his fellow man, a description on a broader structural level of the world of “interpersonal relations.” Buber has made a significant contribution to understanding Mitwelt through his analysis of “I-thou” relationships (1936). Eigenwelt, literally the “own world,” has to do with the self’s relation to itself.

A fourth theory in existential psychology and psychiatry has to do with the time dimension. Heidegger’s great contribution, writes Straus (1936), was to “vindicate time for existence,” and he adds that time is to psychology what mathematics is to physics. Existential psychotherapists, following Heidegger here (1927), place particular emphasis on how the patient relates to the future time dimension: they do not rule out concern with the past but see it as having meaning in terms of the present and the future. The depressed patient, as Minkowski has indicated (see May et al. 1958, p. 127), is characterized by being unable to live in the future, unable to hope, or to project himself into the morrow. Minkowski reverses the usual explanation that the patient cannot hope because he is depressed and proposes that the more useful approach explains that the patient is depressed because he has lost the capacity to live in this future dimension of time. May (1966a) points out that in therapy the acceptance and working through of the subject-object dilemma gives the patient a new sense of freedom with respect to time and the capacity to use time in the service of self-chosen goals. [SeeTime, article onpsychological aspects.]

A fifth common theory, already alluded to, emphasizes choice, responsibility, and freedom. As Laing puts it, “…the task in psychotherapy [is] to make … an appeal to the freedom of the patient” (1960, p. 64). Freedom is real, not illusory, and it derives from the self-constitutive powers of the Dasein. I am the object, for example, of conditioning, of bodily factors, of limitations of time and space, to say nothing of limitations of understanding and perceptions and all the outside forces determining me. But insofar as I am conscious of these facts I am subject, and I can, and to some extent must, choose the attitude I will take toward them. A person exercises choice in structuring his modes of being and his world. He bears the responsibility for his being-in-the-world even as it manifests itself in his dreams; in other words, one is responsible even where least free. Sartre (1943) has made the famous statement “existence precedes essence,” which in effect implies that the human being has unlimited freedom to transform himself. Such an extreme existentialism, however, is not held by adherents of the other existential theories, who emphasize that both essentialist and existentialist elements are necessary for any comprehensive psychology. Existential psychotherapy by no means ignores the infinite number of deterministic elements in the patient’s life and problems, but it believes that helping the patient explore and become aware of these deterministic elements enlarges the sphere of the patient’s freedom to choose his relationship to these determining facts. The acceptance of limitations is thus not a negative process but itself gives the basis for creative self-actualization.

Maurice Friedman has compiled a comprehensive and critical anthology of selections from the whole range of existentialist writings. Organizing the material around the central issues rather than around authors, Friedman is able to highlight the differences between disparate philosophies of existentialism, but more importantly, to demonstrate the common emphasis on the dynamics, the concrete, personal involvement and commitment. Furthermore, he makes clear the area of intersub-jectivity, which is most crucial for understanding similarities and differences among contemporary existentialists. “A distinction must be made between such thinkers as Heidegger, Sartre, and Tillich, for whom the intersubjective tends to remain a dimension of the self, and such thinkers as Buber, Marcel, Jaspers, and Camus, who in one way or another see the relations between man and man as central to human existence” (Friedman 1964, p. 173).

Current research

We shall mention a variety of research studies, the first having to do with precisely the problem we have just been discussing. It is represented by a recent study by Vera Gatch (1963) on the effect of philosophical commitments to psychic determinism or freedom on the behavior of the psychotherapist. Gatch matched a group of ten existentialist therapists against ten orthodox Freudian therapists who were committed to the theory of determinism. One highly significant difference she found between these two groups was that the existential therapists referred to issues of choice, decision, and responsibility with their patients much more frequently than did the Freudian therapists.

Another type of research is Erwin Straus’s classical work on sensory experience. Straus shares a major concern of the phenomenological-existential psychiatrists and psychologists, which is the extent to which traditional theoretical commitments implicitly structure experimental investigations and consequently predetermine the results. “Experiments alone do not guarantee pure empiricism,” he writes ([1936] 1963, p. 4) and goes on to point out how contemporary empirical, “objective” psychology is shot through with limiting and distorting metaphysical biases. In an extensive and detailed analysis of Pavlov’s work and its Cartesian

underpinnings, Straus demonstrates that Pavlov ignored the basic difference between the relationship of an organism to stimuli and of an experiencing being to the world of objects (p. 21). In reducing sensing to epiphenomena of physiological processes occurring within an organism, violence is done to the observable facts. The essence of sensory experience is its intentionality. Sensory impressions imply questioning, seeking, and expecting orientations to the world (p. 101).

Straus forcefully demonstrates the inadequacy of conditioning theory, as well as its theoretical derivatives, in explaining even the behavior of Pavlov’s dogs, let alone the behavior of humans. His critique is based on a careful phenomenological study of the descriptions of the dogs’ behavior given by Pavlov himself. Straus shows that Pavlov was highly selective, since he chose to deal with only those aspects of the total experimental situation that fit his philosophical presuppositions. Straus’s concern, however, is not primarily to criticize Pavlov. His major aim is to reclaim sensory experience from the reductionism of physics and physiology and to restore it to its central position in a psychology of human experience.

In a similar vein, Joseph Lyons (1963) has set himself the task of re-evaluating fundamental concepts of contemporary clinical psychology. He claims that psychology has been dominated by the intention to predict and control behavior rather than by an interest in understanding the reality of the human person. A scientific psychology of people can only be established on a phenomenological basis and requires two conditions: (1) that the perceived be a person, not an “impersonal other,” and (2) that the perceiver act as a full human being. Psychology then becomes “the science of persons as they are apprehended by other persons.” Lyons analyzes a host of concrete, traditional clinical problems in the context of this perspective, emphasizing, as does Straus, the central role of intentionality. For example, he argues that even the stimulus in the typical stimulus-response experimental situation partakes of the subject’s intentional state. The stimulus is given special meaning by virtue of the subject’s readiness for it, and a full description of such a stimulus must take that into account.

Another type of research going on at several universities is the study of subjects’ responses, on the Rorschach or similar tests, not with the question of what the response itself means, but with the question of what it means that the subject is able to give such and such a response. The question, then, is not simply how does the subject structure his world, but what is occurring that enables him to structure his world this way or that, and what decision and selective processes go on in this structuring. Such studies are examining the intentionality—-in the phenomenological-existential sense—that goes into responses and the potentiality that makes the responses possible. Caligor and May (1967) made a study of the intentionality shown in the symbols in one patient’s dreams through an entire psychoanalysis. They propose that a clearer and more trustworthy prediction of what is occurring and going to occur in the patient’s therapy could be made from noting how the patient forms and reforms his symbols at various stages in the therapy than from the patient’s conscious verbal communications with the therapist.

Ronald Laing (e.g., Laing & Esterson 1965), a leading exponent of the applications of the phe-nomenological approach to psychoanalysis, has been studying the family interaction processes of schizophrenic patients. Combining the interpersonal and phenomenological frameworks, Laing maintains that schizophrenia becomes intelligible as the result of ambiguous and contradictory environmental processes. It is a protective device for living in an otherwise hopelessly confusing environment—a strategy for survival. Laing avoids the concepts of “disease” and “pathology” and demonstrates that what happens in a group will be intelligible if one can retrace the steps from what is going on to who is doing what. His work suggests modifications of traditional views of such phenomena as regression, acting out, catatonia, and transference.

The focus of study for Leslie Farber (1966) has been a psychology of will, a subject notably absent in psychological theory and research. Farber observes that although we recognize the presence of many causes for any behavior, we attribute the motivating power to a single aspect of the causal nexus, such as libido, sexuality, or anxiety. However, the only prime mover that is held accountable, answerable, is will, man’s power of volition. When a personality theory does not deal with an explicit, accountable will, it smuggles it in under another name and makes it an irresponsible, that is, unaccountable, prime mover. The focus then shifts to motives as the prime causes of behavior. As a consequence, the phenomenological understanding of both will and motives suffers. Farber points out that will and motive are superficially similar in that both may be involved in provoking action. But a motive cannot be responsible for an action of will. For example, acting disparagingly may be motivated by envy. But since one could also choose not to disparage, even though envious, it is will that is responsible for the action, not envy. Farber concretely applies his concept of the privileges and limitations of the will to a range of clinical issues such as anxiety, schizophrenia, and sex.

Existential analysis (“Daseinsanalyse”)

Existential analysis, in contradistinction to existential psychotherapy, is a type of phenomenological, empirical investigation of specific and actual forms and patterns of existence. In other words, given the essential structure of human nature described by Heidegger (1927) as “being-in-the-world,” the existential analysts, among whom are the Swiss psychiatrists Binswanger and Boss, direct their attention to the particular, concrete modes of being-in-the-world of a particular person. They attempt to understand (in contrast to explaining) the subjectively experienced complex of meanings that constitute a given person’s world designs.

Understanding versus explanation

It is in the contrast between understanding and explanation that the difference between existential analysis and psychoanalytic theory may be explicated. Understanding involves comprehending the object on its terms,

to see in it structures that emerge from its side, and not from ours. … In explanation, the phenomena as they appear are transformed in the sense that they are either subsumed under laws that relate them to other, different phenomena, or they are broken down into parts that somehow are taken as more real than the configuration of those parts that are taken to make up the phenomenon in question. (Binswanger [1922-1957] 1963, pp. 38-39)

In this sense psychoanalytic theory is an explanatory system, and Freud’s conception of man as Homo naturalis, that is, as essentially a biophysical organism, places psychoanalytic theory within the domain of natural science. As such, the “psychic apparatus” is a derivative of biological instincts, and the experienced world is explained by transforming it into its biological components. Binswanger pays great tribute to Freud’s genius in developing the first thoroughgoing natural science view of man. His criticism of Freud is not that his theoretical structure is erroneous but that it is limited. Psychoanalytic theory deals with but one mode of being-in-the-world, namely, what Heidegger calls “thrownness.” The mode of “thrownness” is that which is structured or determined by one’s biological and constitutional make-up (the Umwelt) and conditioned by one’s past experience. It is the mode of being-in-the-world without freedom.


Although existential analysis examines the person and his world without regard to criteria of health or pathology, the very notion of the essential structure of Dasein generates a concept of psychopathology. The essence of Daseinis openness to multiple modes of being-in-the-world and readiness to experience meaning in these multiple modes. Any modification of the essential structure that results in “constriction,” “narrowing,” or “flattening” of the world, so that experience can be organized in only one, or a few, categories, involves a loss of existential freedom and is therefore pathological. Thus far, the only world designs that have been subjected to existential analyses are severely constricted ones. The published existential analytic case studies of both Binswanger (1956; 1962) and Boss (1957; 1962) are all of psychotic or severely neurotic patients. It is hoped that analyses of non-constricted modes of being-in-the-world may shed light on the structure of creative world designs.

Creative phenomena

The existential analysts have always showed special interest in creative and spiritual phenomena. They believe that these kinds of phenomena cannot be explained in terms of antecedent or biological components, for the essence of the phenomenon is precisely the emergence of the new. The essence of the creative man is his being-in-the-world in freedom. The existential analysts similarly emphasize that in therapeutic practice a total commitment to psychic determinism rules out seriously entertaining the possibility of freedom of choice and leaves one only able to foster “the illusion of freedom.” Whether or not existential analysis will shed light on the problems of creativity remains to be seen, but at least its methods open up the possibility. We should add that some analysts in the Freudian tradition, and some others who go under the ambiguous rubric “ego psychologists,” do expand the presuppositions of psychoanalytic theory, implicitly and explicitly, and have made contributions which have something in common with the existential approach.


Binswanger and Boss make a sharp distinction between psychoanalytic theory and psychoanalytic therapy. They have much to say about the limitations of the theory, but they value and use the therapy within a new context. Binswanger actually concerns himself less with psychotherapy, being interested chiefly in the “philosophical anthropology” on which therapy is based. Aside from a few descriptive references to the task of therapy as a process of assisting man in his ability to structure his world and a statement about the therapist’s orientation toward encounter with, and understanding of, the whole person, Binswanger accepts Freudian therapy as a potent and effective clinical instrument.

Boss, on the other hand, deals extensively and explicitly with psychotherapeutic practice. Whereas Binswanger’s case histories are exclusively analyses of modes of being-in-the-world, Boss’s case studies are cast in the framework of the therapeutic process. Furthermore, Boss undertakes a detailed examination of the procedures of Freudian therapy and concludes that Freud the therapist is radically different from Freud the mechanistic theorist.

Although Boss’s case studies are instructive in casting traditional psychodynamic concepts into the broader, more meaningful phenomenological framework of existential analysis, there seems to be an oversimplification in both Boss’s image of man and his view of psychotherapy. For example, Boss claims that all anxiety can be removed by love and trust, whereas one of the major contributions of existential thought is its recognition of anxiety as an ontological condition of existence.

What does the designation “existential psychotherapy” mean? Certainly it does not refer to a self-contained depth therapy that is counter to Freudian psychoanalytic psychotherapy, as is the therapy of Jung or Reich. Nor does it refer to a body of special techniques or procedures, although it has made and will presumably make significant contributions to technique. It is more accurate, indeed, to speak of the existential attitude toward, or context of, psychotherapy, since existentialists have thus far focused their attention on the presuppositions underlying all psychotherapies. There are, however, a number of attributes that are descriptive of the existential attitude. Existential psychiatrists and psychologists believe that this attitudinal framework—which is the application to clinical practice of theories mentioned earlier— fosters psychotherapeutic functioning which is more directly relevant to the problems of human beings in our contemporary age and is more consistently efficacious.

The first attribute may be described as observation in the phenomenological mode. That is, the therapist must learn to perceive the patient in terms of his (the patient’s) phenomenal reality and not in terms of the therapist’s theoretical models. The therapist can never know the patient’s experiential world in the same sense that he can know his own. The critical problem is that of participation in the patient’s world, whether one calls the means by which this is done empathy, intuition, partial identification, presence, or encounter. This is obviously such an essential process in any psychotherapy, indeed in all kinds of human interaction, that it is surprising it has not been subjected to research investigation. Hopefully, a future area of psychotherapy research will be the study of the therapist’s inferential processes.

A second attribute is the experiential mode of knowing. “A psychotherapy on existential-analytic bases,” writes Binswanger, “thus proceeds not merely by showing the patient where, when, and to what extent he has failed to realize the fullness of his humanity, but it tries to make him experience this as radically as possible …” (1962, p. 20). The experiential mode applies to the therapist as well. An aspect of his “presence” in the “encounter” with the patient is his experiencing the patient’s communications on many different levels of his own being.

Third, the existential attitude emphasizes a primary, but not exclusive, focus on the “here and now.” It is destructive of the meaningfulness of existence to interpret essential potentialities as solely genetic developmental processes. A person’s whole history is built into all present relationships and is one of the constitutive determinants of them. But to say that the past is the sufficient cause of the present and to examine the past in therapy in this context is an instance of the kind of reductionism the whole existential movement adamantly opposes. At the same time, we caution against the omission of the genetic dimension in the phenomenological approach. Such an omission points to one of the shortcomings of existential analysis— namely, its lack of treatment of psychological development. Some phenomenological purists claim that the developmental processes can never be the subject of phenomenological investigation, but in our opinion a phenomenology of human development makes sense and has in fact been demonstrated in the illuminating studies by Schachtel (1959). In any case, the therapeutic consequences of verbalizations about the patient’s past history is a question which suggests itself as a fruitful area for research. In practice, many therapeutic schools seem to be moving toward emphasis on the patient’s present situation. It is interesting to note that in her study comparing Freudian and “existential” analysts Gatch found that neither group made many references to the patients’ previous experiences, nor did they make many causal interpretations.

Fourth, the existential approach keeps intentionality always at the heart of the therapeutic process. May (1966a) points out that intentionality is shown, in one aspect, in the movements and gestures of the body; thus the body and “instincts” come directly into existential therapy, not as a set of discrete drives but as the totality of movement of the organism. Intentionality is seen as the source of will and decision and also as the area in which human wishing, including the Freudian wish, operates. This central emphasis on intentionality has opened up some areas for constructive therapy which were previously thought to be resistive to all psychotherapy, such as drug addiction.

Bugental (1965) has attempted to elucidate the meanings of the concepts of existentialism within the framework of psychotherapeutic practice. He sees the therapeutic task as the pursuit of authenticity, and this task has two phases. The analytic phase is reparative and is essentially an attack upon the distortions of awareness and being that cripple a person’s existence. The second phase, the ontogogic, “is concerned with the realization of the potential for liberated being” (1965, p. 183).

We conclude with a comment that arises out of the fact that existentialists, because of their commitment to the “inviolability of human experience” and to the phenomenological method of investigation, have tended to eschew systematization and scientific theory construction (Ford & Urban 1963, p. 480). But both approaches are necessary to the advancement of knowledge. Neither scientific conceptualization nor experimentation as such need violate meaningful experience. The best safeguard against their doing so is a thorough clarification of their implicit presuppositions. Existential analysis has insisted on such clarification. It may also construct thereon a broader humanistic scientific theory, as Binswanger and Straus have already begun to do.

Rollo May and Sabert Basescu

[See alsoPhenomenology. Other relevant material may be found inAnxiety; Mental disorders, TREATMENT OF, article onclient-centered counseling; Motivation; Personality: contemporary viewpoints; Psychoanalysis; Religion; and in the biographies ofBuberandHusserl.]


Basescu, Sabert 1962 Human Nature and Psychotherapy: An Existential View. Review of Existential Psychology and Psychiatry 2:149-157.

Binswanger, Ludwig (1922-1957) 1963 Being-in-the-World: Selected Papers. Translated by Jacob Needle-man. New York: Basic Books. → First published in German. Contains a critical introduction to Binswang-er’s existential psychoanalysis.

Binswanger, Ludwig (1956) 1957 Sigmund Freud: Reminiscences of a Friendship. New York: Grune. -” First published as Erinnerungen an Sigmund Freud.

Binswanger, Ludwig 1962 Existential Analysis and Psychotherapy. Pages 17–23 in Hendrik M. Ruiten-beek (editor), Psychoanalysis and Existential Philosophy. New York: Dutton.

Boss, Medard (1957) 1963 Psychoanalysis and Da-seinsanalysis. New York: Basic Books. → First published in German.

Boss, Medard 1962 Anxiety, Guilt and Psychotherapeutic Liberation. Review of Existential Psychology and Psychiatry 2:173-195.

Bubek, Martin (1936) 1958 I and Thou. 2d ed. New York: Scribner. -” First published in German.

Bubee, Martin 1957a Distance and Relation. Psychiatry 20:97-104.

Buber, Martin 1957b Guilt and Guilt Feelings. Psychiatry 20:114-129.

Bugental, J. F. C. 1965 The Search for Authenticity. New York: Holt.

Caligor, Leopold; and May, Rollo 1967 Dreams and Personality Change. New York: Basic Books.

Farber, Leslie H. 1966 The Ways of the Will: Essays Toward a Psychology and Psychopathology of Will. New York: Basic Books.

Ford, Donald H.; and Urban, Hugh B. 1963 Systems of Psychotherapy: A Comparative Study. New York: Wiley.

Friedman, Maurice 1964 The Worlds of Existentialism. New York: Random House.

Gatch, Vera 1963 The Effect of a Philosophic Commitment to Psychic Determinism on the Behavior of the Psychotherapist. Ph.D. dissertation, Univ. of Oklahoma.

Hetdegger, Martin (1927)1962 Being and Time. New York: Harper. → First published as Sein und Zeit.

Jaspers, Karl (1913) 1963 General Psychopathology. Univ. of Chicago Press. -” First published in German.

Kierkegaard, S0ren A. (1844) 1957 The Concept of Dread. 2d ed. Princeton Univ. Press. → First published as Begrebet angest.

Laing, Ronald D. 1960 The Divided Self: A Study of Sanity and Madness. Chicago: Quadrangle Books; London: Tavistock.

Laing, Ronald D.; and Esterson, A. 1965 Sanity, Madness and the Family. Volume 1: Families of Schizophrenics. New York: Basic Books.

Lyons, Joseph 1963 Psychology and the Measure of Man. New York: Free Press.

May, Rollo 1950 The Meming of Anxiety. New York: Ronald.

May, Rollo (editor) 1961 Existential Psychology. New York: Random House.

May, Rollo 1966a Psychology and the Human Dilemma. Princeton, N.J.: Van Nostrand.

May, Rollo 1966b Love and Will. New York: Norton.

May, Rollo; Angel, E.; and Ellenberger, H. F. (editors) 1958 Existence: A New Dimension in Psychiatry and Psychology. New York: Basic Books.

Sartre, Jean-paul (1943) 1956 Being and Nothingness: An Essay on Phenomenological Ontology. New York: Philosophical Library. -* First published as L’etre et le neant: Essai d’ontologie phenomenologique.

Schachtel, Ernest G. 1959 Metamorphosis: On the Development of Affect, Perception, Attention, and Memory. New York: Basic Books.

Straus, Erwin W. (1936) 1963 The Primary World of Senses: A Vindication of Sensory Experience. New York: Free Press. -” First published as Vom Sinn der Sinne.

Straus, Erwin W. Phenomenological Psychology: The Selected Papers of Erwin W. Straus. New York: Basic Books, 1966.

Tillich, Paul 1944 Existential Philosophy. Journal of the History of Ideas 5:44-70.

Tillich, Paul 1952 The Courage to Be. New Haven: Yale Univ. Press. -* A paperback edition was published in 1959.

Van Kaam, Adrian L. 1966 Existential Foundations of Psychology. Pittsburgh: Duquesne Univ. Press.


Although formerly used in a narrower sense to include only business and industrial psychology, today the term applied psychology designates the professional practice (as distinguished from the basic science) of psychology in all areas. It covers applied research and service functions in the fields of personnel, engineering, consumer, clinical, and counseling psychology. In addition, some applied psychologists work with members of other professions as consultants or in the training of other professional personnel. Before World War n, psychology was primarily an academic discipline. Today over half of America’s psychologists work outside of universities, in such settings as government agencies, industrial organizations, school systems, hospitals, clinics, and counseling centers.

The science and profession of psychology

Applied psychology does not differ in any fundamental way from the rest of psychology. In terms of orientation and training, every applied psychologist is a psychologist first and an applied specialist only secondarily. All have taken essentially the same types of courses; specialization occurs chiefly at the level of practicum training and on-the-job experience. The clinical, counseling, or personnel psychologist, for example, has received training in experimental psychology, and the experimental psychologist utilizes in his research concepts or hypotheses that may have originated in the clinic or factory.

The unique contribution of the applied psychologist, as distinguished from that of other specialists, stems largely from his research approach to problems of human behavior. When the psychologist goes to work in an applied setting, he brings with him not a set of rules or specific facts but a method for attacking problems. It is essentially the scientific method, common to all sciences. This method consists in the empirical observation and recording of facts under systematically controlled conditions. By controlling conditions through appropriate experimental designs, the psychologist can identify cause-and-effect relations and can isolate the influence of individual variables. The scientific method also requires replication of observations and a determination of the margin of error inherent in its procedures.

Since applied psychology follows the same fundamental procedures as basic psychological research, how can the two be differentiated? When the applied psychologist is engaged in research— as is true much of the time for many applied psychologists— the distinction hinges on the difference between basic and applied research. This difference is one of degree. Although examples can be found that fall clearly into the basic or the applied category, some research can be classified in either one. One determining factor is the reason for choosing a problem: to help in theory construction (basic) or in making administrative decisions (applied). For instance, is the investigation concerned principally with the nature of learning or with the most effective method for teaching children to read?

Another difference pertains to the specificity or generality of the findings. The results of basic research can be generalized more widely than those of applied research. The latter typically yields results pertaining only to narrowly limited contexts. Similarly, applied research permits less analysis of causal relations, since situations are likely to be compared in their totality rather than being broken down into more elementary components. For example, applied research may demonstrate that one of two training procedures—in all their operational complexities—yields better results than the other in a particular situation. But it may not be possible under these circumstances to specify why the one method was superior.

Some applied psychologists spend most of their time in service rather than in research functions. How does such a psychologist use scientific method when engaged, for instance, in psychotherapy with a neurotic patient, in testing a child with a reading disability, in interviewing an applicant for an executive position, or in planning a consumer survey for an automobile manufacturer? He does so in at least two ways. First, he evaluates and chooses his procedures, not on the basis of subjective opinion, but in the light of available published research conducted in comparable situations. Being unable under the circumstances to carry out his own empirical evaluations, he is nevertheless guided by whatever empirical data are available regarding tests, questionnaire techniques, varieties of psychotherapy, or any other procedure he plans to use.

In a still more general way the psychologist’s scientific training influences his approach to every problem he encounters in his service functions. Through such training he has formed habits of accurate and objective observation and recording of facts, and he has learned to guard against preconceived notions and premature acceptance of conclusions. He has learned to reserve judgment and to modify and discard conclusions as fresh facts become available. In his service functions, as in his research, the applied psychologist often must formulate hypotheses and verify them against

subsequent data

In trying to discover the sources of a client’s neurotic fears, the causes of a child’s reading difficulties, or the leadership potential of a job applicant, the psychologist forms a succession of tentative hypotheses. Each hypothesis suggests what further facts must be elicited and is in turn either confirmed or disproved by such facts. This type of problem-solving attitude represents an important difference between the professional psychologist and both the well-intentioned but untrained “psychologizer” and the deliberate impostor.

The problem of charlatanism

Some of the areas in which applied psychologists work have traditionally proved attractive to charlatans and self-styled experts (see Anastasi 1964, pp. 10-13). In this flourishing psychological underworld are found phrenologists, physiognomists, and others who try to diagnose aptitudes and personality traits or recommend a specific career on the basis of irrelevant physical signs. Here too are the many pseudoscien-tific systems for improving personality, developing one’s memory or selling ability, and overcoming emotional problems. On the borderline are the practitioners who assume a semblance of respectability by administering tests. They may, however, be relying on a single test of unknown validity for which they make extravagant claims. Or they may send a set of tests by mail, to be taken under uncontrolled conditions and interpreted with no other knowledge about the examinee. All these practices represent gross misuse of tests and yield meaningless results.

The prevalence of charlatanism in the field of human behavior arises partly from inadequate understanding of the nature of psychology. Since psychology is a relatively young science, the public is still unclear about the functions of psychologists and is thus more receptive to the claims of charlatans. Even more important in accounting for the survival of charlatanism is the public’s strong desire for the sort of help offered by charlatans. Unhampered by facts, the charlatan promises easier and quicker solutions to life’s problems than does the reputable psychologist. He either omits all mention of any margin of error in his procedures or gives a bland assurance of near-perfect accuracy. In support of his claims he is likely to cite an impressive array of selected cases, thereby capitalizing on chance results. Relying on analogies, figures of speech, and popular stereotypes, his writings create a spurious semblance of plausibility.

A favorite procedure of charlatans is to provide personality descriptions in terms of vague generalities applicable to most people. When confronted with such a description of himself, the individual is often impressed with its apparent accuracy and insight and becomes convinced that the procedure is valid. This subjective pseudovalidation has been called the “Barnum effect” (Dunnette 1957) after Phineas T. Barnum, the famous showman, who is credited with remarking, “There’s a sucker born every minute.” The readiness with which these general personality descriptions are accepted as true has been demonstrated experimentally with such groups as personnel managers and college students (Stagner 1958). In these demonstrations a standard personality inventory is first administered to the group, and the papers are collected for scoring. Before getting the actual scores, each participant receives an identical copy of a fake “personality analysis.” The analysis consists of a list of descriptive statements in which the same statements have been marked for each person. The marked statements, most of which are flattering, are such as to apply to the large majority of people. They are interspersed with unmarked statements, which are generally unfavorable. When asked to evaluate their self-descriptions, the majority of participants rate them as “amazingly accurate,” while most of the others rate them as “rather good.” Few if any disagree with them. Upon being told about the hoax and learning that their own description is identical with all the others, subjects typically show great surprise. The Barnum effect accounts for much of the popular acceptance of pseudoscientific systems of personality analysis. These systems provide random assortments of universally applicable generalities and fail to differentiate one person from another.

Identifying applied psychologists

The prevalence of charlatanism provides one reason for inquiring into ways of identifying genuine psychologists. In addition, the phenomenal growth of applied psychology since World War n means that more and more psychologists are working with laymen or with members of other professions who may lack the technical knowledge to appraise the psychologist’s qualifications. Hence, it has become increasingly important to establish procedures for identifying psychologists and judging their special competencies.

A significant step, both in raising professional standards and in helping the general public to evaluate psychological practitioners, has been the enactment of licensing and certification laws for psychologists. Before World War n there was virtually no legal control over either the practice of psychology or the use of the title “psychologist.” Today most of the states in which large numbers of psychologists are employed either have such laws or are in the process of enacting them (Anastasi 1964, p. 584). In such states psychologists may be identified by the possession of a certificate indicating that certain standards of training and experience have been met. Typical requirements for certification include the Ph.d. degree in psychology from an accredited university, two years of relevant experience, and the passing of a written qualifying examination.

At a still higher level, specialty certification is handled by the American Board of Examiners in Professional Psychology (ABEPP), established in 1946. Requiring the Ph.d. degree, five years of experience, and intensive written and practical examinations, this board issues diplomas in three specialties : clinical, counseling, and industrial psychology. ABEPP publishes a directory of diplomates in each specialty, which is available in libraries and may also be obtained by interested organizations or individuals. The function of ABEPP is essentially to provide information about qualified psychologists. As a privately constituted board within the profession, it has no legal authority for enforcement. On the other hand, the various state laws pertaining to psychology do carry such authority. In a state having such laws a person without the appropriate certificate who presents himself as a psychologist is subject to legal penalties.

Another major source of information about psychologists is the American Psychological Association (APA), the national association to which most psychologists belong. Membership in this association does not imply qualifications for the performance of any service functions—only state certificates and ABEPP diplomas serve that purpose. Nevertheless, the annual directory of the APA provides considerable information about the location, training, and professional functions of its members. The APA has also undertaken many other activities designed to improve and systematize training standards, raise the level of professional practice, work out effective relations with other professions, and clarify the public image of psychology. It has participated in the preparation of two booklets designed to inform the public about the work of psychologists, Psychologists in Action (Ogg 1955) and The Psychologist in Industry (American Psychological Association, Division of Industrial Psychology 1959). Of particular importance was the formulation of a professional code of ethics, “Ethical Standards of Psychologists” (American Psychological Association 1963). First published in 1953 and revised in 1963, this code is especially relevant to the problems encountered by applied psychologists in their relations with the public.

Personnel psychology

One of the major areas of personnel psychology is that of personnel selection and classification. In industry the techniques of personnel selection and classification are used not only in hiring new employees but also in connection with promotions, transfers, discharges, and other personnel decisions. Nor are such techniques limited to industrial psychology. Essentially the same procedures are applicable to the selection and classification of military personnel, the admission of students to colleges and professional schools, and the identification of patients most likely to benefit from a particular form of therapy. Although first developed within the context of industrial psychology, these techniques provide an introduction to methodology that is of basic importance in most fields of applied psychology. [SeeIndustrial relations, article onindustrial and business psychology.]

A useful distinction is that between selection and classification of personnel. Selection always involves a decision to accept or reject. Decisions as to whether or not to hire a job applicant, admit a student to medical school, or accept a candidate for officer training are examples of selection. In classification, on the other hand, every individual must be utilized. The question is where to assign each person so as to maximize the total effectiveness of the organization. The development of a program for either selection or classification of personnel involves four principal steps: job analysis, preparation and preliminary tryout of predictors, validation of predictors, and formulation of a strategy for personnel decisions (Anastasi 1964, chapters 2-5).

Job analysis defines the problem by specifying worker qualifications for which predictors are needed. Through a variety of techniques for the systematic observation of workers on the job, a job description can be prepared that is specific to each job. A description in terms of vague generalities that would be equally applicable to many jobs is of little use for personnel selection or classification. Moreover, effective job analysis identifies critical requirements, that is, those characteristics that differentiate most sharply between better and poorer workers on each job.

On the basis of the job analysis suitable predictors are chosen or developed. These include not only tests but also other assessment procedures, such as application forms, reference checkups, and interviewing. Application forms (or biographical inventories) have proved successful in a wide variety of selection situations, particularly when their items are empirically chosen and weighted by checking them against criteria of subsequent job performance. Although more time-consuming than other techniques, intensive interviewing provides opportunities for thorough individual assessment. Interviewing techniques are employed especially in the evaluation of executives and other high-level personnel and in the judging of many personality traits for which no satisfactory tests may be available. At a more basic level considerable research has been conducted on the development of rating scales and other systematic procedures for improving personal judgments (Anastasi 1964, pp. 76-88). [SeeInterviewing.]

Every major type of test has been used in personnel selection and classification (Anastasi 1961). Traditional intelligence tests measure principally verbal comprehension and other abstract functions required for academic achievement. Several short intelligence tests have been developed for screening industrial personnel. Research on creative talent has produced many new testing techniques that are relevant to certain selection problems. Among the earliest tests applied to personnel selection are tests of special aptitudes in motor skills, spatial aptitudes, mechanical comprehension, and clerical speed and accuracy. Classification programs are making increasing use of multiple aptitude batteries, which combine the traits measured by traditional intelligence tests with some of the broader abilities covered by special aptitude tests. Achievement tests measure current proficiency following relatively uniform training or experience. Many consist of standardized work samples, such as taking dictation, operating a punch press, or handling the matters in an executive’s in-basket. Personality tests may be used with any type of worker but have found their chief application in jobs requiring extensive interpersonal contacts, such as selling and supervisory positions. It is especially important in this area to guard against common misuses of tests, including undue reliance on test scores in the absence of other information and the use of inadequately validated instruments. Among the most successful personality tests are interest inventories, whereby the individual may compare his interests with those typical of persons engaged in different occupations. [SeeAptitude testing; Intelligence and intelligence testing; Personality measurement; Vocational interest testing.]

Prior to their operational use all predictors should be validated within a representative sample of the population for whom the selection program is designed. The most common procedure is to correlate predictive measures (e.g., test scores, interviewer’s ratings) with a criterion of subsequent job success. On the basis of such predictive validity some of the instruments will be retained and others discarded or modified. The validation data also permit an evaluation of the effectiveness of the final selection program and a determination of the margin of error to be expected in its operation. [SeePsychometrics.]

The final stage in the development of the program requires the choice of a strategy for applying the predictive measures so as to reach a decision about individuals (Cronbach & Gleser 1957). Scores on the different predictors may be combined through a regression equation, which yields the single best estimate of each individual’s criterion performance. Through such a procedure deficiencies in one qualification may be compensated by superior standing in another. In jobs where minimum standards must be met in each of several essential skills, a multiple-cut-off strategy is more appropriate. When tests or other predictors are employed in the intensive study of individual cases, as in the selection of high-level personnel, evaluation of executives, and clinical diagnosis, it is a common practice for the examiner or interviewer to combine and interpret scores through “clinical judgment,” with no further statistical analysis (Meehl 1954).

A growing area within personnel psychology is that of development and training (Anastasi 1964, chapter 5; Gagne 1962, chapters 9-11). Although the psychology of learning has much to contribute to the improvement of training procedures, well-designed applied research in this area is still rare. Industrial training is a continuing process that can benefit all employees, from beginners to experienced workers and from unskilled labor to top management. Training programs in industry serve a variety of functions, including orientation, development of job skills, technical and professional training, management development, and general education.

The development of a training program should include task analysis to define what must be learned, development of appropriate training procedures, and objective evaluation of the program. The choice of training media and procedures depends in part upon what is to be taught and to whom. In developing training procedures, one can also be guided by the results of available training research in connection with such questions as motivation, stress, practice, feedback, and transfer of training. The effectiveness of a training program should be evaluated in terms of job criteria as well as training criteria.

Recent developments in the automation of training procedures are illustrated by training devices, simulators, and teaching machines. The rapidly growing area of management development covers many types of training and utilizes a diversity of training techniques. Much of it is concerned with the development of human-relations skills and attitudes through group discussion of specific cases, problem-solving interviews, and role playing (Maier, Solem, & Maier 1957). In other aspects of management development two techniques of special interest are management games (or simulation) and creativity training through “brainstorming.” The former provides practice in executive decision making, often utilizing computers to furnish rapid feedback on the probable consequences of decisions (Fleishman 1961, pp. 219-238). The latter endeavors to stimulate creative productivity by requiring participants to separate in time the production of ideas from their evaluation (Parnes & Meadow 1963). It is hypothesized that the individual is thus freed from the customary inhibitory effects of self-criticism.

A third and relatively broad area of personnel psychology is concerned with employee motivation and morale (Anastasi 1964, chapter 6; Fleishman 1961, sees. 4-6). Variously designated as “industrial social psychology,” “employee relations,” “human relations in industry,” and “the psychology of management,” this division of personnel psychology dates from the classic Hawthorne studies, which first focused attention on the effect of employee attitudes upon productivity (Roethlisberger & Dick-son 1939). Incidentally, the Hawthorne studies also served to highlight the need for controlling attitudi-nal variables in the design of psychological experiments. The term “Hawthorne effect” is now commonly used to designate the influence that participating in an experiment may have upon the subject’s behavior.

The principal procedures used in gathering data on employee motivation, attitudes, and morale include interviews, opinion questionnaires, attitude scales, projective and other indirect techniques, nominating or sociometric techniques, and continued observation of small groups by a trained observer. When rating the factors that make for job satisfaction, workers usually place as high a value on security, opportunity for advancement, interest in their work, feeling of pride in the company, and relations with co-workers and supervisors as they do on pay. However, the relative weight given each factor varies somewhat with the age, sex, and education of the worker, as well as with type of work and job level. Favorable employee attitudes are associated with a lower accident rate and with less absenteeism, tardiness, and job turnover. The relation between attitudes and productivity, however, is more complex and depends upon other individual and situational variables. There is also evidence to suggest that favorable job attitudes more often arise from intrinsic characteristics of the work itself, while unfavorable job attitudes more often arise from the job context (Herzberg, Mausner, & Snyderman 1959). Moreover, favorable attitudes bear a more direct relation to productivity than do unfavorable ones.

The attitudes and morale of any group are deeply influenced by the supervisory practices, the communication system, and the organizational structure under which it operates (Likert 1961). Research on supervisory and leadership behavior has identified two independent dimensions: “consideration,” characterized by a friendly, warm, considerate supervisory relationship, as contrasted with an impersonal and authoritarian relationship; and “initiating structure,” pertaining to the extent to which the supervisor actively plans and directs group activities oriented toward goal attainment (Fleishman 1961, pp. 311-328). Both dimensions are related to employee attitudes and productivity.

Research on industrial communication has covered such varied problems as the relative merits of different media; legibility, content, and readability of written communications; the development of communication skills; factors influencing the persuasiveness of communication; sources of communication barriers and breakdowns; and the nature and effectiveness of communication networks (Fleishman 1961, sec. 6).

Organizational structures have been analyzed from many points of view, and this diversity of approach is reflected in the proposals for improving organizational effectiveness (Foundation for Research on Human Behavior 1959; Bass 1965). Although controlled experiments pertaining to organizational theory are few, some research is available on the effectiveness of such organizational practices as employee participation in decision making, sociometric work-group assignments, and the redesigning of jobs with reference to attitudinal factors (Fleishman 1961, sees. 4-6). While all these approaches are promising, it must be borne in mind that no single organizational formula, management procedure, or supervisory practice fits all jobs and all individuals.

Engineering psychology

In current usage engineering psychology is a rather flexible term. This flexibility also characterizes its various synonyms—human engineering, human-factors engineering, and ergonomics. All these terms are sometimes used in a broad sense to cover practically every topic in industrial psychology, including selection, training, motivation, work methods, working environment, and equipment design. A more common usage restricts the coverage to the last three topics, as is done in this article. It should also be noted that the techniques of engineering psychology extend beyond industrial psychology and are being applied more and more to the designing of consumer goods. Psychologists are contributing not only to the designing of industrial machinery, military equipment, and space vehicles but also to the designing of such products as kitchen stoves, radios, and telephone dials. [SeeEngineering Psychology.]

A major objective in the improvement of work methods is the reduction of fatigue (Anastasi 1964, chapter 7; Barnes 1958, chapter 14; Fleishman 1961, sec. 7). Fatigue has been variously defined in terms of feelings of tiredness, changes in output, and physiological conditions. Increase in the energy cost of work, as measured by the respiration calorimeter, illustrates the physiological concept of fatigue. Vigilance tests provide a promising behavioral index of fatigue. Feelings of monotony and boredom are difficult to differentiate from the subjective experience of fatigue, especially from so-called mental fatigue.

Human efficiency can be increased through the design of work and rest schedules. Suitably scheduled rest pauses generally increase total output, although the improvement may not occur immediately. Lengthening the work week beyond an optimal number of hours has usually lowered rather than raised total output. Shift work involves a disruption of daily physiological rhythms, especially for workers on rotating shifts. Individuals differ widely in their ability to adjust to changing activity cycles.

Beginning with the early contributions of Frederick W. Taylor and Frank B. Gilbreth, time-and-motion study has now become part of more comprehensive methods-improvement programs (Barnes 1958). The principal objective of time-and-motion study is the elimination of unnecessary movements in work processes. Modern methods-improvement programs are broader in scope than early time-and-motion study, and they give more attention to individual differences and worker participation in methods development.

Accident prevention is a recognized objective of modern methods improvement, besides being related to nearly every other aspect of industrial psychology (Anastasi 1964, chapter 7; Fleishman 1961, sec. 8). Data on the relation of personal characteristics to accident rate are often difficult to interpret because of the interrelation of many personal variables. Accident-proneness can be conclusively demonstrated only through the comparison of individual accident records over different time periods. Studies of “psychological climate” in different industrial settings have shown accident rates to be significantly related to several situational variables. With the recognition of the importance of such variables as causes of traffic accidents, the methods of engineering psychology are being used increasingly to improve the layout, illumination, and marking of highways. Accidents can be regarded as one indicator of the deterioration of performance under adverse conditions.

It has long been known that working efficiency depends in part upon the characteristics of the working environment. It is apparent that such problems pertain not only to factories and offices but also to schools, libraries, homes, waiting rooms, and any other environments designed for prolonged human use. From a different angle, recent developments in space travel have stimulated intensive research on the effects of certain extreme environmental conditions upon human performance.

With regard to illumination, research has concentrated on the optimum intensity of light for different types of work, the distribution of light to minimize glare and other conditions producing visual fatigue, and the use of different colors of light (McCormick 1964, chapter 13). The primary object of ventilation is to enable the body to give off excess heat through evaporation, radiation, and convection (McCormick 1964, chapter 15). Industrial studies have shown significant effects of ventilating conditions upon the quantity and quality of production, accident rates, and absenteeism. Suggestive results on the behavioral effects of weather, seasons, and climate were obtained in a number of early studies (Anastasi 1964, pp. 203-204). Recently there has been a revival of interest in these problems, known collectively as “psychocli-matology.” Research is also being conducted on the psychological consequences of exposure to extreme atmospheric conditions, among which oxygen deprivation has received the greatest attention from psychologists.

Chief among the special psychological problems of space travel are those arising from extreme and stressful environmental conditions (McCormick 1964, chapter 16). The physical conditions investigated in this connection include weightlessness, rotation, high accelerative forces, and conflicting sensory cues leading to spatial disorientation. A major source of psychological stress is isolation, comprising the factors of confinement, detachment, and sensory deprivation. [SeeSpace, outer, article onsocial and psychological aspects.]

Noise has been investigated as a cause of temporary or permanent hearing impairment, as a source of interference with auditory communication, and as a major form of distraction (McCormick 1964, chapter 14; Fleishman 1961, pp. 512-519). The effects of noise distraction upon behavior depend upon the interaction of various characteristics of the distracting stimuli, the task, and the individual. Their proper interpretation requires data not only on output but also on energy expenditure, adaptation, and emotional response to the source of distraction. A suggestive hypothesis, for which some experimental evidence is available, is that performance is most effective when the subject is at an optimum level of arousal (McBain 1961). Thus the introduction of a varying noise should improve the performance of an intrinsically monotonous task, since it brings the initially low arousal level closer to the optimum.

Although foreshadowed by the contributions of Taylor, Gilbreth, and other early investigators, research on human factors in equipment design dates largely from World War n (Anastasi 1964, chapter 9; Barnes 1958, chapters 16-17; McCormick 1964, chapters 5-12). As the complexity of machines began to outstrip man’s capacity to operate them, it became necessary to redesign equipment in such ways as to make the operator’s task less demanding. One of the problems of equipment design concerns the spatial layout of work. This is illustrated by the pre-positioning of pens, screwdrivers, and other small tools in holders and by the semicircular work space within which all materials or controls are easily reached by the operator’s hands. Another problem pertains to the improvement of displays through which information is transmitted to the operator. For example, extensive research has been conducted on the factors influencing speed and accuracy of dial reading, such as dial size and shape, length of scale units, number and spacing of scale markers, direction of pointer movements, and the size and style of letters and numerals. Research on control problems is illustrated by the hundreds of experiments on tracking. Another example is provided by research on the coding of controls in terms of position, size, shape, or color. Confusion among controls can be reduced by standardizing each control, increasing the discrim-inability of different controls, and utilizing meaningful associations for their identification.

The broadening scope of engineering psychology is best typified by its growing concern with man-machine systems (Fleishman 1961, sec. 9; Gagne 1962; McCormick 1964, chapters 17-19). By describing the functions of the human operator in engineering terminology, such an approach makes it possible to transfer some of these functions from the man to the machine. The systems approach also permits the efficient arrangement of men and machines within a complex system. It is through the study of man-machine systems that the greatest improvements in speed and accuracy of operation have been achieved. It is also through this approach that engineering psychology is most likely to contribute to the advancement of basic psychological knowledge.

Consumer psychology

While personnel and engineering psychology are concerned chiefly with the behavior of the individual as producer, consumer psychology deals with his behavior as consumer (Anastasi 1964, chapters 10-12). This field of psychology began with the psychology of advertising and selling, whose objective was effective communication from the manufacturer or distributor to the consumer. Through advertising the consumer is informed about available goods or services and about the ways in which they may meet his needs. More recently, consumer psychology has broadened to cover two-way communication—from consumer to producer as well as from producer to consumer. Communications from the consumer were first sought as a means of preparing more effective advertisements. Systematic surveys of consumer needs and wants enabled the advertiser to identify those features of his product that were of greatest interest to the consumer. Such consumer surveys led directly to the next step, which involved the consideration of consumer wants and preferences in the designing of products.

The methods of consumer psychology are applicable to a number of fields other than that of developing and marketing industrial goods and services. One such application is to be found in public opinion polls, whose procedures are essentially the same as those of consumer surveys. Another example is provided by the well-designed research on food preferences conducted by the armed services as an aid in the planning of meals for military personnel. A final illustration is the use of advertising campaigns in connection with problems of public interest, ranging from the prevention of forest fires to the promotion of mental health. {SeeConsumers, article onConsumer behavior; Market research, article onconsumer research.]

Modern consumer psychology covers a wide variety of problems, and its methods are correspondingly diverse. One of its most active areas deals with procedures for testing the effectiveness of printed advertisements, such as readership surveys, analysis of coupon returns, and controlled surveys of brand use and sales records. Specialized techniques have been developed for measuring the extent to which an ad attracts and holds attention, is understood and recalled, arouses appropriate associations and feeling tones, and leads to the desired action. Through controlled field or laboratory investigations, the effectiveness of ads in all these respects has been related to such ad characteristics as size, color, amount of white space, illustrations, printing type, content of the written message, position in the medium, and number of repetitions. Research on trade names has dealt with such questions as ease of identification and recall, arousal of appropriate feeling tone, and avoidance of confusion with other trade names.

In radio and television research a variety of specialized techniques has likewise been employed to gather data on audience size and composition, audience reaction to specific programs or to types of programs, and sales effectiveness of advertising.

A flurry of public agitation regarding subliminal advertising has proved to be largely unfounded (McConnell, Cutler, & McNeil 1958). Subliminal perception is the process of responding to stimuli that fall below the threshold of verbally reported awareness. The results of laboratory experiments indicate that subliminal stimulation cannot appreciably affect the behavior of mass audiences, contrary to the claims of certain popular writers and of the promoters of this type of advertising.

Cutting across several areas of consumer psychology, motivation research utilizes depth interviewing and projective techniques to study buying motives. The principal contribution of this approach lies in providing hypotheses for subsequent testing by more objective, quantitative methods applicable to large samples. Information regarding consumer motivation can also be obtained by more direct forms of inquiry if suitable experimental designs are employed. The “product image,” which refers to the composite of ideas and feelings associated with a product, has been investigated by the methods of motivation research as well as by more controlled techniques such as adjective checklists and the semantic differential. [SeeAdvertising, article Onadvertising research.]

Personal salesmanship may be regarded as the most flexible and individualized form of advertising. Because of the many varieties of selling, generalizations about effective salesmanship are likely to be of little value. Psychologists have concentrated on procedures for the selection and training of salesmen for specific jobs. Available research on the sales process is still relatively meager.

Clinical psychology

Characterized by intensive work with individual cases, clinical psychology is concerned chiefly with intellectual and emotional disorders (Anastasi 1964, chapters 13-15; Shaffer & Shoben 1956). Today clinical psychologists work in a variety of settings, including not only hospitals and outpatient clinics but also industry, schools, prisons, courts, government agencies, and the armed services. The practice of clinical psychology utilizes findings and techniques from many branches of psychology, such as abnormal psychology, personality theory, and psychological testing. The specific activities of clinical psychologists consist chiefly of diagnosis, therapy, and research, although the relative emphasis placed upon each varies widely with the work setting and with the individual psychologist. Moreover, these three functions are frequently intertwined. Research may be specifically concerned with the validity of diagnostic tools or with the effectiveness of different types of therapy. Similarly, diagnostic and therapeutic procedures are indistinguishable in certain types of psychotherapy that emphasize the therapeutic value of the client’s insight into the nature and origin of his problems. [SeeClinical Psychology.]

In its broadest sense, diagnosis corresponds to the fact-finding aspect of clinical practice. Its objectives include screening and classification, personality description, prediction of outcome, and attainment of insight by the client. In the classification of psychological disorders a basic distinction is that between mental deficiency and emotional problems, the latter being subdivided into psychoses and neuroses. More specific syndromes have been identified, but the application of these traditional psychiatric categories has many drawbacks. Characteristically the clinical psychologist is interested in a detailed personality description of the individual case, with its unique combination of problems, adjustment mechanisms, and antecedent circumstances.

The major sources of data available to the clinician include the case history, psychological testing, and the diagnostic interview. Considerable discussion and some research have been devoted to the nature and effectiveness of “clinical judgment” (Meehl 1954). With regard to both data gathering and interpretation, there are a number of ways in which the services of a skilled clinician are needed. Whether objective diagnostic techniques and statistical prediction formulas can eventually assume the entire diagnostic function remains a moot point.

Many kinds of therapy are used today in treating emotional disorders. The choice of therapy depends partly upon the nature and severity of the disorder and partly upon such client characteristics as age and intelligence. To a considerable extent, however, the type of therapy employed reflects the training and theoretical persuasion of the therapist, available facilities, and other extraneous factors. The same behavioral symptoms may be treated quite differently by different therapists; and several types of therapy may be combined in treating a single individual. There are few forms of treatment that are wholly specific to a given emotional disorder. In psychology, as contrasted to medicine, one rarely if ever finds a disorder in which the diagnosis completely determines the treatment. Evaluating the relative efficacy of different forms of therapy for emotional disorders is very difficult. Owing to methodological difficulties, there is as yet little evidence to demonstrate that one therapy is better than another for any given case or even that any therapy is effective at all. Since the practical demands of the situation call for some action, the therapist does the best he can within the limits of available knowledge.

Available therapies for emotional disorders include somatic therapies, environmental therapies, psychotherapy, and preventive procedures. Somatic therapies, requiring the services of a licensed physician, are illustrated by psychosurgery, shock therapies, and various applications of psychopharmacology. The introduction of tranquilizers has led to a spectacular rise in the recovery rate of patients in American state mental hospitals. A major factor in these results appears to be the role of tranquilizers in making patients more amenable to psychotherapy and, indirectly, improving staff morale. Other, more direct effects of such drugs have not yet been conclusively established in adequately controlled experiments. Environmental therapy includes the therapeutic manipulation of environmental conditions both in community contexts (e.g., home, school, job, or recreational centers) and in institutions. A growing emphasis upon milieu therapy is rapidly transforming mental hospitals from custodial institutions into therapeutic communities. [SeeMental disorders, treatment of, article onsomatic treatment.]

Psychotherapy is practiced in many forms, reflecting the diverse theoretical orientations of the therapists. In the most general terms, psychotherapy can be described as the use of verbal or other means of communication in a nonthreatening interpersonal situation that facilitates the alleviation of anxiety and the elimination of maladaptive behavior through a learning process. Two widely used types of psychotherapy are psychoanalysis (Dol-lard & Miller 1950) and client-centered therapy (Rogers 1951). Group therapy is increasingly being employed, either in place of individual psychotherapy or in conjunction with it. Psychodrama and role playing are special variants of group therapy. Play therapy is commonly utilized with children, in lieu of the predominantly verbal techniques employed with adults. The current mental health movement is concerned not only with the treatment and rehabilitation of institutionalized mental patients but also with preventive measures and with the fostering of positive mental health through comprehensive social and educational programs. [SeeMental disorders, treatment of, articles onclient-centered counselingandgroup psychotherapy.]

It is in research that the clinical psychologist, as contrasted with other mental health professionals, can make his most distinctive contribution (Conference on Research in Psychotherapy 1962). Even in his service functions, the clinical psychologist with a research orientation can operate more effectively than one who is trained only as a practitioner. With research training he is better able to evaluate innovations and incorporate new developments into his practice. In a rapidly evolving field rigid commitment to existing techniques can only retard progress.

A major area of applied research in clinical psychology deals with the validity of diagnostic procedures, particularly protective techniques and other special clinical instruments. Research on the process of psychotherapy has been concerned with changes in client behavior in the course of therapy, the specific ways in which different therapists function, and the interactions among therapist, client, and process variables (Rogers & Dymond 1954).

Special techniques have been developed to measure changes in the client’s self concept in the course of therapy. The outcome of therapy is particularly difficult to measure satisfactorily. Among the criteria of outcome employed for this purpose are client reports, the therapist’s evaluation of progress, objective measures of behavioral changes during therapy sessions, ward behavior of institutionalized cases, and follow-up data in real-life situations.

Research on the causes of mental disorders is an interdisciplinary venture spanning many fields, from biochemistry to anthropology. The sources of intellectual and emotional disorders have been sought in heredity, environmentally produced organic conditions, and experiential factors. Basic research that integrates clinical and experimental approaches is beginning to make vital contributions both to clinical practice and to the science of psychology. The reformulation of clinical concepts in terms of learning theory has been especially productive of research that cuts across clinic and laboratory lines (Dollard & Miller 1950; Grossberg 1964).

Counseling psychology

While there is much overlapping between the work of clinical and counseling psychologists, the latter typically deal with relatively normal persons having minor emotional problems or wanting help in vocational, educational, or other practical decisions (Anastasi 1964, chapter 16; Bordin 1955; Tyler 1961). Like psychotherapy, counseling relies largely on verbal communication and an accepting interpersonal relationship. In contrast to psychotherapy, however, counseling is less concerned with changing the individual’s basic personality structure and more concerned with the effective utilization of his present resources. Counseling is also likely to be of shorter duration than psychotherapy and to involve the giving of more factual information to the client. Counseling psychologists work in many settings and perform a variety of functions. Although they may specialize in one type of counseling, such as vocational, educational, employee, rehabilitation, old-age, marriage, or personal counseling, they recognize the interrelation of all adjustment problems and concentrate on counseling the whole person. [SeeCounseling Psychology.]

To increase the client’s self-knowledge and assist him in making decisions, counseling psychologists utilize several types of tests, notably intelligence tests, educational achievement tests, special aptitude tests, multiple aptitude batteries, interest inventories, and personality inventories. Because of the importance of vocational decisions in most counseling activities, counseling psychologists need to make current occupational information available to their clients. Both tests and occupational data should be integrated in the counseling process in such a way that the client accepts the information and uses it effectively (Bordin 1955; Goldman 1961; Tyler 1961). An important objective of counseling is to facilitate decision making, not only by providing self-knowledge and occupational or other relevant information but also through training in the decision process.

One of the principal areas of counseling research concerns the process of occupational choice and the nature of vocational development throughout the life span (Anastasi 1964, chapter 17; Roe 1956; Super 1957; Super & Overstreet 1960). In selecting an occupation, the individual chooses a way of life. One’s occupation is likely to affect not only his income level and general social status but also many specific aspects of daily life. Job satisfaction and general mental health are contingent upon the extent to which the individual’s work satisfies needs and values that are significant to him. Considerable information is available on personality patterns characteristic of persons in different occupations, but the results are often difficult to interpret because of procedural inadequacies. Some research has also been done on the role of childhood experiences in vocational choice. [SeeVocational Interest testing.]

Psychology and other professions

Chief among the fields in which psychologists work in consulting or collaborative relations with other professional personnel are education, medicine, and law (Anastasi 1964, chapters 18-20). In education, psychologists may serve as school psychologists or as educational psychologists. The functions of school psychologists consist largely in the diagnostic testing and interviewing of individual pupils, followed by recommendations for remedial action. Educational psychologists are concerned principally with teacher training and educational research. While their chief focus is on the psychology of learning, they also draw upon other areas, notably developmental psychology, differential psychology, psychological testing, the psychology of adjustment, and social psychology. [SeeEducational psychology.]

The potential contributions of psychology to medicine are still largely undeveloped. Although psychological techniques and knowledge can aid in every stage of medical practice, including diagnosis, treatment, rehabilitation, and prevention, contacts between psychology and general medicine

prior to World War II were negligible. Since mid-century the participation of psychologists in medical school teaching has grown rapidly. There have been corresponding increases in the utilization of psychologists as members of interprofessional teams, as for example, in the rehabilitation of the physically handicapped. Psychologists are likewise engaging more and more in collaborative research projects conducted in medical settings. [SeeVocational Rehabilitation.]

The earliest applications of psychology to law were concerned with the evaluation of testimony and other courtroom procedures. A related area is that of lie detection. In an effort to identify the causes of antisocial behavior, psychologists have studied the characteristics of delinquents and criminals. Although the conditions that lead to crime are manifold, research findings give increasing prominence to emotional and motivational factors stemming, at least in part, from childhood experiences. The work of psychologists in court clinics, prisons, training schools for juvenile delinquents, and other penocorrectional settings falls chiefly within the fields of clinical and counseling psychology. At a more basic level, psychologists may aid in the development, revision, and interpretation of laws by submitting relevant research findings in court testimony, by serving as consultants to legislative committees, and by collaborating in law school teaching and research. Empirically established facts about human behavior are basic to many types of laws, such as those pertaining to insanity, drug addiction, alcoholism, sexual offenses, child development, education, and minority groups.

Anne Anastasi

[Directly related are the entriesAdvertising, article onadvertising research; Clinical psychology; Consumers, article onconsumer behavior; Counseling psychology; Educational psychology; Engineering psychology; Industrial relations, article onindustrial and business psychology; Market research, article onconsumer research; Military psychology. Other relevant material may be found inAptitude testing; Fatigue; Learning, article onacquisition of skill.]


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Foundation For Research On Human Behavior 1959 Modern Organization Theory: A Symposium. Edited by Mason Haire. New York: Wiley.

Gagne, Robert M. (editor) 1962 Psychological Principles in System Development. New York: Holt.

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Grossberg, John M. 1964 Behavior Therapy: A Review. Psychological Bulletin 62:73-88.

Herzberg, Frederick; Mausner, Bernard; and Snyder-man, Barbara Bloch 1959 The Motivation to Work. 2d ed. New York: Wiley. → The first edition was published in 1957.

Likert, Rensis 1961 New Patterns of Management. New York: McGraw-Hill.

Mcbain, William N. 1961 Noise, the “Arousal Hypothesis,“and Monotonous Work. Journal of Applied Psychology 45:309-317.

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The term psychology has been used to refer to the study of the soul, consciousness, behavior, the mind, or the brain, depending on the era and cultural context investigated. In the nineteenth century German philosopher-psychologist Friedrich Eduard Beneke (1798-1854) defined his new psychology as the natural science of inner experience and suggested that the subject matter of psychology was what one finds in oneself. His countryman Wilhelm Wundt (18321920), who is often considered one of the central figures in the creation of modern psychology, defined the subject matter of psychology as the total content of experience in its immediate character. William James (18421910), one of the pioneers of American psychology, defined psychology as the science of mental life, both of its phenomena and of its conditions.

In a 1989 study, Tracy B. Henley and his colleagues showed that in the first third of the twentieth century psychology was defined the majority of the time as including concepts of mind, consciousness, or mental activity. Between 1930 and 1969, the prime time of behaviorism, these terms were barely mentioned in North American psychology, although with the coming of the cognitive revolution they became widely used again. Use of the term behavior increased throughout the twentieth century, with later definitions including both behavior and mental activity. Definitions of psychology reflect the dominant research programs in a particular context.


Psychology did not exist as an independent discipline before the nineteenth century, although psychological topics were studied long before then. The study of the soul (psyche ) goes back to Greek philosopher Aristotle (384322 BCE) who wrote a pioneering work entitled, in Latin, De anima (On the soul). Aristotle discussed the five senses as well as perception, thinking, and imagination. He also discussed memory and dreaming. He did not study intelligence quotient (IQ), motivation, or prejudice, however, which are all later psychological constructions.

In the eighteenth century German philosopher and mathematician Christian Wolff (16791754) divided the study of the soul into two parts: rational psychology and empirical psychology. Rational psychology depicted what the human soul was capable of. He discussed the souls substantiality, simplicity, immateriality, immortality, as well as the mind-body problem, and provided logical proofs that the soul was immaterial. Empirical psychology aimed to identify psychological principles on the basis of concrete experiences of what actually happened in the human soul. Empirical referred to something that could be determined through experiences rather than reason. Wolffs empirical psychology addressed the ability of the soul to know and to desire, the interaction of the soul and the body, and the faculties of the soul. Psychology concerned the study of the soul until the mid-nineteenth century, when German philosopher Friedrich Albert Lange (18281875) proclaimed a psychology without a soul.

Present-day psychology covers a wide range of topics such as biological bases of behavior, sensation, perception, memory, cognition, emotion, motivation, learning, language, dreaming, social interaction, prejudice, development, aging, intelligence, personality, stress, psychopathology, and psychotherapy. In psychology each concept is subdivided and studied in its parts: For example, memory is subdivided into short-term memory, long-term memory, working memory, explicit memory, and implicit memory, among others. Memory can be researched from a developmental, social, or biological perspective, each of which provides a variety of theoretical frameworks.


In the sixteenth century the word psychologia (psychology) first appeared in a book title, although some research does indicate earlier usage of the term. In 1590 Rudolf Goclenius (1547-1628), a German professor of physics, mathematics, logic, and ethics used the term.

Some historians suggest that the acceptance of psychology as an institution of research and teaching at universities first occurred during the first half of the nineteenth century during a period of transformation for German universities. With the establishment of state-funded and state-controlled classical high schools, professors of philosophy were asked to teach courses on psychology and pedagogy for classical high school teachers-in-training. Because psychology was understood as the scientific basis for pedagogy, teacher candidates were required to take exams in the discipline of psychology. Horst Gundlach (2004) offers 1824, the year in which Prussia established psychology as an examinable discipline at its universities, as the origin of the discipline of psychology. Most books on the history of psychology, however, list its inception from 1879, the year in which Wundt began to conduct psychological experiments in his new psychological laboratory at Leipzig, Germany. From a critical perspective it is difficult to attribute the birth of a discipline to a single event. The institutionalization of psychologythe establishment of an academic discipline that followed university rulesoccurred at different times in different geographical or national contexts.


Psychology as a profession or an expert occupation became a reality in the twentieth century. The professionalization of psychology can be linked to the development of other institutions in European and North American culture. The transformation of the legal system required experts, for example, regarding the validity of testimony and the reliability of memory; the health system needed experts in dealing with the mental health problems of patients; the prison system sought professionals who could provide information on the progress of rehabilitation and the likelihood of re-offending; the school system needed expertise in order to determine which children would need special education; and industry and corporations needed experts on personnel selection, the improvement of productivity, and advertising. In all of these applied fields psychologists emerged and claimed scientific knowledge.

In addition, public demand for psychological expertise increased; for example, regarding the parenting of children, people sought advice on the adequate amount of emotional contact, sensory stimulation, potty training, masturbation, and the appropriate extent of parental control at different ages. The search for expertise on how to have fulfilling romantic relationships, to be successful, and even live life led to the birth of pop psychology. Prominent examples of pop psychologists include former academic John B. Watson (1878-1958), whose book Psychological Care of Infant and Child (1928) contained historically contingent ideas such as that one should never hug or kiss a child, and Dr. Phil McGraw, whose media-magnified psychological activities are largely rejected by academic psychologists. There were a number of troubling manifestations of the professionalization of psychology as well: German psychology expanded in the context of the militarization of the fatherland at the beginning of the twentieth century; and U.S. psychologists, using IQ tests, labeled populations from Eastern and Southern Europe and non-European races mentally inferior during the great immigrations of the same time period.


According to Steven Ward, psychologys integration with other institutions has made it a uniquely successful field. Psychology flourished in the twentieth century in terms of its intellectual and social expansion. Psychology is one of the most popular undergraduate majors in North America and many European countries. The American Psycholog ical Association (APA), the largest association of psychologists worldwide, has 150,000 members. The APA has more than fifty divisions that cover traditional experimental, social, developmental, or clinical psychology; the psychological study of lesbian, gay, and bisexual issues; peace psychology; and the advancement of pharmacotherapy, among many other diverse topics.

There are several thousand journals dedicated to psychology, and the APAs Publication Manual (2001), a style guide, has been adopted by most psychologists and by professionals in other disciplines as well. As a profession psychology pervades popular consciousness in the twenty-first century. The increasing global dominance of American psychology after 1945 reflects the economic power of the United States. But psychology did not only succeed as an institution; it also thrived in the psychologization of human life. The public and many expert cultures explain human and social events in psychological terms: Individual decisions, the arts, political crises, economic problems, history, and terrorism are all explained with the help of psychological categories.


The importance of psychology as a scientific discipline and in everyday life is clear. However controversies regarding basic precepts continue among psychologists.

The Dualism of Psychology Psychology can comprise understanding or explaining psychological objects and events. For example, one can explain the physiological mechanisms of memory or one can understand the specific content of a persons memory that is formed within meaningful life experiences. Psychologists with a natural-scientific orientation emphasize the explanation, prediction, and control of behavior or cognition, while psychologists with a human-scientific perspective focus on thinking, feeling, and willing based on the assumption that reflection, intention, and action are meaningful processes. German philosopher Wilhelm Dilthey (1833-1911) provided a systematic foundation for two types of psychology when he divided the discipline into descriptive (human-scientific) and analytical explanatory (natural-scientific) parts. He argued that psychologys subject matter was human experience and thus its method must be understanding. German experimental psychologist Hermann Ebbinghaus (1850-1909) endorsed psychology as a natural science that did not need the method of understanding and should rely on natural-scientific explanation and experimental methods. Wundt, who many see as the father of German experimental psychology, divided the science into an experimental branch that focused on precise analysis of the basic processes of consciousness, and an observational Völkerpsychologie (cultural psychology) that covered complex psychological processes that accompany the development of human communities and mental products in the context of values, customs, and language.

In the North American tradition Gordon Allport observed an increasing nomothetic, natural-scientific commitment of psychology, but he petitioned for the inclusion of an idiographic approach in scientific psychology. Human-scientific approaches (hermeneutic, existential, humanistic psychologies) generally have been marginalized since the twentieth century, although they have never been totally abandoned, especially in clinical contexts. The impact of the natural-scientific approach was so powerful that even Sigmund Freud considered his method of psychoanalysis to be natural-scientific. The dualism of psychology is surfacing again in discussions surrounding quantitative versus qualitative methods, with the latter gaining more acceptance in the early twenty-first century.

Unification Dualism is one facet in an ongoing discourse regarding unification. Since the end of the nineteenth century, theoretical psychologists and later Russian psychologist Lev Semyonovich Vygotsky (1896-1934) have critiqued the missing unity of psychology. In the first half of the twentieth century the focus was on the unification of large research programs such as psychoanalysis, behaviorism, Gestalt psychology, and structuralism, and later unification was demanded regarding the multiplicity of theories, approaches, and empirical results that were often contradictory. Psychology as it exists in the early-twenty-first century is so diverse in its conceptual and theoretical positions and so fragmented in its identity that multiple psychologies rather than a unitary psychology have prevailed.

Solutions to the unification problem in the past have largely been based on a conceptual reductionism in promoting a single program such as behaviorism. Some have called for unifying theories of unification before any unification of the discipline could succeed. Proponents of unification demand unification for theoretical reasons. For example, the increasing demand for interdisciplinary work must remain fragmented if it is not clear what the discipline of psychology stands for. Opponents of unification suggest that the lack of unity makes psychology an extremely adaptive discipline that is able to work with other fields in academic and applied settings. The factual lack of theoretical unity has led to the phenomenon that mainstream psychology identifies itself by the commitment to a specific methodology, namely an experimental-statistical point of view.

Dichotomies Psychology throughout its history has struggled with conceptualizing the relationship between society and the individual, nature and nurture, and mind and body. The lack of an adequate conceptualization of the individual and society has led to criticisms that psychology is too individualistic in its theories and practices. For example, a persons psychological distress regarding homelessness cannot solely be explained, understood, and solved on an individual level. Even social psychology, which by definition should take the social context into account, does not provide ecological relevance because many studies use undergraduate students in laboratories as subjects. Klaus Holzkamp (1972) argues that in the real world there are many more variables that influence behavior and cannot be included in their complexity in an experiment.

The mind-body problem has been addressed in behaviorism in a reductionist way by denying or neglecting the reality of a mind. Neuropsychological researchers have developed more sophisticated theories since the late twentieth century. The largest political impact derives from an inadequate conceptualization of the nature-nurture debate. This dichotomy is most prominent in IQ controversies but also surrounds the heritability of pathologies, personality, and other psychological characteristics. The lack of an adequate understanding of nature-nurture has led psychologists to make premature judgments about alleged inborn intelligence. The heritability of intelligence received widespread public attention in the context of British educational psychologist Cyril Burts (18831971) fraudulent data on twins and in connection with the issue of race. As Stephen Jay Gould and others have pointed out many interpretations were unsupported by data but these interpretations were presented as factual knowledge. Many of the premature conclusions should be labeled epistemological violence (Teo 2005).

Natural Kinds versus Social Kinds More recently there has been a debate regarding whether psychological concepts are natural kinds or social kinds. Kurt Danziger (1997) suggests that many psychological concepts are social constructions that have become social reality. This idea has had an impact on research and practice and means that psychological concepts are bound to culture not to nature. Thus American or European psychology, indigenous psychologies themselves, cannot be exported straightforwardly to another cultural context. Many psychologists are often unaware that in believing their concepts can be used globally, they display misplaced ethnocentricity.

Professionalization The professionalization of psychology itself is a debated topic in academia. There have always been proponents and opponents, and this struggle has continued into the twenty-first century. For example, in the United States an American Psychological Society was founded in 1988 as a response to APA, which was perceived as catering to the interests of applied psychologists but not academics. One of the recent topics discussed in the context of the profession are prescription privileges for psychologists in some U.S. states. This topic is significant because it connotes a shift from a psychological to a medical model of mental illness. From the perspective of health insurers, allowing psychologists to prescribe drugs means cost reduction. However, giving such rights to psychologists challenges a long-standing privilege reserved to medical doctors, with probable economic consequences for that profession.

SEE ALSO Achievement; Allport, Gordon; American Psychological Association; Anxiety; Attention-Deficit/Hyperactivity Disorder; Attitudes, Behavioral; Autokinetic Effect; Behavior, Self-Constrained; Behaviorism; Bettelheim, Bruno; Body Image; Brazelton, T. Berry; Child Behavior Checklist; Child Development; Cognition; Cognitive Dissonance; Consciousness; Contempt; Coping; Dementia; Depression, Psychological; Diathesis-Stress Model; Erikson, Erik; Family Functioning; Festinger, Leon; Foucault, Michel; Freud, Sigmund; Fromm, Erich; Gender; Gilligan, Carol; Goffman, Erving; Guttman Scale; Hite, Shere; Infidelity; Ingratiation; IQ Controversy; James, William; Jones, Edward Ellsworth; Jung, Carl; Kinsey, Alfred; Locus of Control; Maccoby, Eleanor; Manic Depression; Marital Conflict; Mechanism Design; Memory in Psychology; Mental Health; Mental Illness; Mental Retardation; Milgram, Stanley; Nature vs. Nurture; Neuroscience; Oedipus Complex; Operant Conditioning; Optimism/Pessimism; Overachievers; Overeating; Pavlov, Ivan; Post-Traumatic Stress; Priming; Professionalization; Psychoanalytic Theory; Psycholinguistics; Psychometrics; Psychosomatics, Social; Psychotherapy; Pygmalion Effects; Race; Racism; Realism; Realism, Experimental; Rotters Internal-External Locus of Control Scale; Scarr, Sandra Wood; Self-Control; Self-Esteem; Sexuality; Sherif, Muzafer; Skinner Box; Skinner, B. F.; Social Psychology; Spock, Benjamin; Steele, Claude M.; Stereotype Threat; Strategies, Self-Handicapping; Stress; Stress-Buffering Model; Underachievers; Undereating; Zimbardo, Philip


American Psychological Association. 2001. Publication Manual of the American Psychological Association. 5th ed. Washington, DC: Author.

Danziger, Kurt. 1997. Naming the Mind: How Psychology Found Its Language. London: Sage.

Gould, Stephen Jay. 1996. The Mismeasure of Man, revised and expanded. New York: Norton.

Gundlach, Horst. 2004. Reine Psychologie, Angewandte Psychologie und die Institutionalisierung der Psychologie [Pure psychology, applied psychology, and the institutionalization of psychology]. Zeitschrift fuer Psychologie 212 (4): 183199.

Henley, Tracy B., Michael G. Johnson, Elizabeth M. Jones, and Harold A. Herzog. 1989. Definitions of Psychology. Psychological Record 39 (1): 143152.

Holzkamp, Klaus. 1972. Kritische Psychologie: Vorbereitende Arbeiten [Critical psychology: Preparatory works]. Frankfurt am Main: Fischer.

Smith, Roger. 2005. The History of Psychological Categories. Studies in History and Philosophy of Biological and Biomedical Sciences 36: 5594.

Teo, Thomas. 2005. The Critique of Psychology: From Kant to Postcolonial Theory. New York: Springer.

Vygotsky, Lev Semyonovich. 1997. The Historical Meaning of the Crisis in Psychology: A Methodological Investigation. In Problems of the Theory and History of Psychology. Vol. 3 of The Collected Works of L. S. Vygotsky, eds. Robert W. Rieber and Jeffrey Wollock, 233343. New York: Plenum.

Ward, Steven C. 2002. Modernizing the Mind: Psychological Knowledge and the Remaking of Society. Westport, CT: Praeger.

Thomas Teo

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PSYCHOLOGY. At the turn of the twentieth century, the German psychologist Hermann Ebbinghaus remarked that "psychology has a long past, but only a short history." He was referring to recent scientific interest in the experimental study of the mind and behavior that was characteristic of the "new" psychology. Beginning with a few laboratories in Germany and the America in the late nineteenth century, the field of psychology grew significantly throughout the twentieth century, especially in the United States. Psychological terms have infiltrated everyday language, a huge mental health industry has arisen, and psychological tests have become ubiquitous. Psychology is embedded in modern life. How are we to define this protean field and to explain its rise?

Interest in understanding and explaining human nature and actions is as old as the first stirrings of self-consciousness among humans. Western philosophy has a long tradition of thinking about causes and consequences of human action, both individual and social. Within that general field, psychology has drawn particularly from scholarship on ethics (i.e., moral rules of conduct) and epistemology (theory of the method or grounds of knowledge).

The advent of modern scientific inquiry and methodology in the seventeenth century transformed European culture as it spread to philosophical comprehension and technological practice during the Enlightenment in the eighteenth century. By the nineteenth century, science had become a legitimate and growing profession; the physical world, biology, and society became subject to scientific scrutiny.

Modern psychology as a discipline formed during this period. Psychology's conceptual roots can be found in the experimental laboratories of physiologists, in the medical practices of asylums and clinics, and in the statistical manipulations of mathematicians.

After 1870, college students in the United States gradually became aware of the "new" psychology: William James, a professor at Harvard University, introduced theories of mind and demonstrated empirical findings with a collection of so-called "brass instruments," borrowed from laboratories of physics and physiology. James wrote the classic Principles of Psychology in 1890.

James was associated with the functionalist school, which studied the mind's adaptation to its environment. Habits, consciousness, and the self were understood as adaptive functions, not as structural elements of the mind. The influence of Charles Darwin was evident in the functionalists' interest in evolutionary processes; they investigated the development of mind and behavior in other species as well as humans. Between 1870 and 1910, many students from the United States traveled to Germany to study. Attracted by low travel costs and inexpensive accommodations as well as the reputation of German universities, students were exposed to the ideas and practices of scholars such as Wilhelm Wundt, professor of philosophy at the University of Leipzig. A founder of modern psychology, Wundt wrote voluminously on psychology as an independent academic discipline and, in 1879, established the first psychological laboratory.

Conceptually, Wundt espoused a broad view of scientific psychology, ranging from individual psychophysiology and mental chronometry to human language and culture. Different topics needed different research methods. For instance, when measuring the speed of the nervous impulse, accurate mechanical timers gave readings of 1/1,000 of a second; when a colored light was used as a stimulus for a psychophysics experiment, precise introspection provided qualitative judgments about the light's color, intensity, and other characteristics; when religious practices were being investigated, historical and comparative methods of textual analysis were employed.

Wundt and James, both nonpracticing medical doctors, were recognized leaders of the new psychology; in Vienna, another physician, Sigmund Freud, was developing his own system of psychology and psychotherapy, which he called psychoanalysis. His system was spread through an apprentice method of "training analysis" before the psychotherapist began a private practice. Psychoanalysis in America became associated with the medical profession, developing separately from academic psychology.

An American Science

Fresh from their exposure to the new psychology, graduates adapted laboratory techniques and intellectual agendas to the rapidly changing landscape of higher education in the United States. During the last quarter of the nineteenth century, the research ideal was fused with values of social utility and liberal culture to give rise to the modern university. In 1876, only one university, Johns Hopkins, offered graduate instruction leading to the Ph.D.; by 1900, scores of institutions offered doctoral level studies and degrees.

More than forty psychological laboratories had been established in U.S. colleges and universities by 1900. Experimental work concentrated on sensation and perception, using the reaction-time method where a stimulus was presented to a subject and the speed of response was accurately measured. Professors published their research findings in the American Journal of Psychology beginning in 1887, the Psychological Review beginning in 1894, or other scientific periodicals. The field grew rapidly in American universities and colleges. The American Psychological Association (APA), a professional body dedicated to the advancement of psychology as a science, was formed in 1892, with 26 charter members. Psychologists were also active in the child-study movement and in trying to advance the art and science of pedagogy, newly significant with the rise of universal education. Differences in theory and methods gave rise to schools of thought (structuralism, functionalism, behaviorism, Gestalt, etc.) that were more apparent to insiders than to the public.

Applications of psychology and psychological theory to education expanded significantly with the spread of mental tests. Starting in 1905, French psychologist Alfred Binet published scales on testing for intelligence in children. Stanford University psychologist Lewis Terman subsequently revised the tests and included the ratio of mental and chronological ages, resulting in the "Intelligence Quotient" (IQ). In 1916 the "Stanford-Binet" debuted. Mental tests were widely used in World War I to classify soldiers for general intelligence and occupational specialties. After the war, personnel psychology, particularly in business and industry, became a recognized specialty.

By 1929, at the start of the Great Depression, psychology was firmly institutionalized in higher education. Although the APA reached 1,000 members that year, during the 1930s its dominance diminished as psychologists founded new organizations to pursue their scientific and professional interests. Occupational trends led to a split between academic and applied psychologists, and to marked gender differences, with the majority of females confined to low-status jobs in nonacademic settings.

The "Age of Learning"

By the start of the 1930s, psychology had matured to the point that the discipline generated internally a system of scientific priorities, preferred methods of investigation, and complex reward arrangements. Experimental research was dominated by the use of behavioristic methods in the service of a general theory of learning. In a seminal article in 1913 published in the Psychological Review, "Psychology as the Behaviorist Views It," John B. Watson strongly urged psychologists not to look within at unseen mental processes, but to concentrate on observable behavior. Watson had earned his doctorate from the University of Chicago in 1903 with a thesis on rat psychology. Later investigators made the white rat a standard laboratory subject, and Watson's ideas were reformulated into a variety of neo-behavioristic perspectives.

Among the prominent neo-behaviorists was B. F. Skinner (who earned a doctorate from Harvard in 1931), who developed a theory of behavior known as "operant conditioning." In contrast to the "classical conditioning" associated with the Russian physiologist Ivan Pavlov in which a stimulus is substituted for an already existing response, operant conditioning focuses on a class of emitted responses that are followed by reinforcement. For example, a rat in a "Skinner box" (an apparatus with a lever to obtain food and/or water) presses the lever (the operant) and eats (reinforcement). With each trial, the rat is more likely to repeat the action (response strength). Through a series of ingenious experiments, Skinner demonstrated the scientific utility of his approach in the laboratory before later extending it to the realm of teaching machines, social engineering (with the 1948 utopian novel Walden Two), and an air-conditioned baby crib, all of which engendered controversy.

The Aftermath of World War II

World War II was a watershed for psychology in many ways. The war gave rise to the practice of clinical psychology that was strongly supported by the federal government. New techniques and tools borrowed from other disciplines transformed the intellectual life of psychology. Increased funds were available for scientific research; the number of psychologists grew dramatically; and the APA reorganized to include all areas of psychological activity under a federated governing system.

The academic psychology department remained the basic unit for research, education, and training. The G.I. Bill, a robust economy, and a widespread consensus on the positive value of a college degree helped usher in a "golden age." Psychology grew on the broadening foundation of undergraduate education.

The introductory course exhibited the diversity of psychology while presenting the prevailing orthodoxy of scientific professionalism. A new wave of undergraduate textbooks was written. For instance, Ernest R. Hilgard published Introduction to Psychology in 1953. Firmly based in the research literature, the book attempted comprehensive coverage of topics ranging from the nervous system to personal adjustment. One innovation in format was the use of sidebars to break up the main mass of text and provide additional details on selected topics. Successful textbooks often went through multiple revisions over the course of 30 or more years.

By the early 1960s, employment trends had shifted decisively to nonacademic settings, thus the majority of psychologists found work in hospitals, schools, clinics, corporations, and private practice. That led to increased concern over the professional aspects of psychology, including interprofessional relations with psychiatrists and social workers who were a part of the expanding mental health industry. Some psychologists took their message directly to the general public, contributing to the literature of lay psychology or to the robust market in self-help books. For instance, B. F. Skinner explained his system of operant conditioning to the general public, beginning in 1953 with Science and Human Behavior, and Carl R. Rogers introduced his approach to psychotherapy with the mass-market textbook On Becoming a Person in 1961.

The Rise of Cognitive Psychology

Perhaps the most striking intellectual development of the post–World War II period was the rise of cognitive psychology. Cognitive psychology covers the whole range of human mental activity, from sense perception to memory and thought. With deep roots in nineteenth-century research on attention, memory, and language, cognitive psychology developed an institutional focus at Harvard University's Center for Cognitive Studies starting in 1962. In an influential survey of the field, psychologist Ulric Neisser explained in Cognitive Psychology (1967) that the physical stimuli that an object produces "bear little resemblance to either the real object that gave rise to them or to the object of experience that the perceiver will construct as a result." It is this constructive activity that provided the foundation for cognitive psychology.

Closely allied with the study of cognition is mathematical psychology. Curve-fitting, mathematical modeling, and inferential statistics are used to explain experimental results as well as a source for theory construction. By the early 1950s coursework in the analysis of variance became a common feature of graduate training in the United States. Its routine use, standardized and codified in textbooks, meant that psychologists did not have to understand the complexities of statistics to apply them to their work.

Statistics were useful in addressing quantitatively the inconsistencies of individual human behavior. People behaved differently at different times, and what they did in one experimental setting might have little relation to what they did in another. Statistical treatment of group data combined data from many individuals, enabling certain patterns to emerge that were characteristic of the statistical group, even though the actual behavior of any particular member of the group might not conform to the statistical "average."

Mainstream psychology was not without its critics. Some urged turning away from apparent "methodolatry," while others descried the "physics envy" that grew out of attempts to emulate the physical (and precisely measurable) sciences. A movement toward humanistic psychology was prompted by dissatisfaction with behaviorism's narrow methods and the psychoanalytic focus on childhood pathology. This so-called "third force" represented an attempt to place human values at the core of psychological theory and practice rather than mechanical virtues or developmental doctrine.

At the close of the twentieth century, psychology remains a protean discipline dedicated to the pursuit of scientific knowledge as well as a potent profession serving the mental health needs of Americans. Neither a single set of assumptions nor a common methodology unites the work of psychologists. How psychologists prospered by exploiting this diversity is an intriguing area for historical investigation.

History of Psychology

Psychologists and others have exhibited a sustained interest in the history of the field since the rise of the "new" psychology. In his three-volume A History of Psychology (1912–1921), George Sidney Brett traced the philosophical background of modern psychological thought, from the ancient Greeks to his day. Edwin G. Boring, considering Brett's work too philosophical, was motivated to write A History of Experimental Psychology in 1929; Boring argued for the primacy of scientific research, saying "The application of the experimental method to the problem of mind is the great outstanding event in the history of the study of mind" (p. 659). Boring's book became the veritable Bible for courses in the history and systems of psychology. History was also used as a resource for asserting the unity of psychology despite the proliferation of diverse viewpoints.

After World War II, the history of psychology was pursued for two decades mostly as a teaching subject within psychology departments. In the mid-1960s the field became increasingly professionalized with new university programs starting and the APA founding a history division. A specialized journal, Journal of the History of the Behavioral Science (1965), and a society, Chiron: The International Society for the History of the Behavioral and Social Sciences (1969), provided support for scholars. In addition, professional historians, notably historians of science and medicine, grew more interested in and paid more attention to the history of psychology.

In 1966, Robert M. Young published a scathing review of the literature in the history of psychology and related fields in the journal History of Science. Since that time, scholarship in the history of psychology has steadily deepened. Developments in the late twentieth century included the establishment of the Forum for History of Human Science, a special-interest group of the History of Science Society formed in 1988, and an APA-sponsored journal, History of Psychology established in 1998.

In the pages of an 1893 McClure's magazine, Herbert Nichols, one of the first students awarded a doctorate in psychology from an American university, boldly predicted that "the twentieth century will be to mental science what the sixteenth century was to physical science, and the central field of its development is likely to be America." In broad outline, Nichols's prediction came true. But the road leading from the era of brass instruments and introspection to the age of computers and cognitive science proved to be both long and with many byways. World wars, economic depression as well as prosperity, and the rise of American higher education provided the setting and context for the growth of psychological thought and practice. Psychology today is intellectually multiparadigmatic, professionally pluralistic, and ideologically diverse. Psychologists, more than a quarter million strong in the United States, have had and continue to have a tremendous impact on the culture of modern science.


Boring, Edwin G. A History of Experimental Psychology. 2d ed. New York: Appleton-Century-Crofts, 1950. An influential account by a prominent psychologist-historian.

Burnham, John C. "On the Origins of Behaviorism." Journal of the History of the Behavioral Sciences 4 (1968): 143–151. The classic statement of the historical problem of behaviorism.

Capshew, James H. Psychologists on the March: Science, Practice, and Professional Identity in American Psychology, 1929–1969. New York: Cambridge University Press, 1999. A study of the impact of World War II on the profession of psychology.

Danziger, Kurt. Constructing the Subject: Historical Origins of Psychological Research. New York: Cambridge University Press, 1990. A penetrating account of the standardization of methodology and the resultant conceptual and professional power it generated.

Hale, Nathan G., Jr. Freud in America. 2 vols. New York: Oxford University Press, 1971–1995. A judicious and balanced historical narrative.

Heidbreder, Edna. Seven Psychologies. New York: Century, 1933. A sensitive contemporary account of the major schools of psychology.

Herman, Ellen. The Romance of American Psychology: Political Culture in the Age of Experts. Berkeley: University of California Press, 1995. A nuanced examination of the role of psychology in public affairs and policy from 1940 to 1975.

Hilgard, Ernest H. Psychology in America: A Historical Survey. San Diego: Harcourt Brace Jovanovich, 1987. An authoritative encyclopedic survey.

O'Donnell, John M. The Origins of Behaviorism: American Psychology, 1870–1920. New York: New York University Press, 1985. An analytic narrative focused on the transition from philosophy to psychology.

Smith, Roger. The Norton History of the Human Sciences. New York: Norton, 1997. Psychology is the backbone of this massive and informative synthesis that ranges from sixteenth-century thought to twentieth-century American institutions.

Sokal, Michael M., ed. Psychological Testing and American Society, 1890–1930. New Brunswick, N.J.: Rutgers University Press, 1987. Essays that explore the construction, use, and impact of mental testing.

James H.Capshew

See alsoIntelligence Tests ; Psychiatry .

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PSYCHOLOGY. The term psychology first appears in the sixteenth century, denoting the study of the human soul (Greek psyche, 'soul'), a part of what was then called anthropology: the term is used thus in the first work to use it as a title, Rudolf Goclenius's Psychologia of 1594 (the title uses the Greek word). The term continued to be used in this way through the seventeenth century. Only in the early eighteenth century, with the publication of Christian Wolff's Psychologia Empirica (1732) and Psychologia Rationalis (1734), does it take on its modern sense, supplanting earlier terms like scientia de anima ('science of the soul'). The study of the soul, or the mind, did not, of course, begin in the eighteenth century. But it may, with some reason, be said to have begun again in the seventeenth.


From the mid-thirteenth century, when Aristotle's works became the basis of the baccalaureate curriculum in European universities, until the middle of the sixteenth, the starting point for the study of the soul was Aristotle's De anima. Hundreds of commentaries on it were published in the sixteenth and early seventeenth centuries. Often they included lengthy disputations on controversial topics, like the immortality of the soul and the nature of the rational soul. In the latter part of the sixteenth century the commentary form began to be abandoned in favor of the systematic textbook, of which Francisco Suárez's De Anima (1621; On the soul) is a noteworthy example. A reader of these works would have encountered the major ancient, Arab, and medieval interpretations of Aristotle and a fair helping of empirical observations, mostly from ancient authorities like Pliny and Galen, but also occasionally from such recent authors as Andreas Vesalius (15141564), whose De Humani Corporis Fabrica (1543) superseded the ancients on anatomical questions.

The subject matter of De Anima is life and the functions of life. Aristotle treats not only sensation, memory, imagination, and the intellect, but also what would now be thought of as purely physiological functions like digestion and reproduction. The task of the science of the soul is to define the soul itself and the functions proper to living things, to describe the organs and mixtures of elements that subserve them, and finally to establish the principles on which a classification of plants and animals is to be based.

The soul is what Aristotle calls a "form": it confers on matter the characteristics proper to a certain species of thingthe human, say. Medieval authors called the soul a "substantial form," substantial because like the body it is the bearer of properties. It is not the eye, Aristotle says, but the soul that sees. Every material substance, living or not, has a form; the soul is defined among material forms as that of "an organic body potentially having life." Certain functions are found only in the things we call living; the soul is the form proper to them. Although the soul requires a particular composition and configuration of matter to perform its functions, and some materials like blood and bile are found only in living things, neither the soul nor its functions can be reduced to mere mixtures or concatenations of nonliving stuffs.

The functions of living things were divided into three groups: vegetative, sensitive, and rational. All living things nourish themselves, grow, and reproduce. Animals, but not plants, have senses and can move about. Humans can do all that animals do; moreover, they can reason and exercise free will. The soul is accordingly divided into three parts. Only for the rational part, peculiar to humans, can it be argued that its operations do not require a material organ, and that therefore it can survive the dissolution of the body.

The predominant theory of sensation among Aristotelians was "species theory." Sensing consists in the reception of species (Latin species, 'aspect' or 'appearance') in the sense organ. Each sense has its own "proper sensibles"there are species of color, sound, odor, and so forth. Species from the various senses are combined in the "common sense" (sensus communis) and then stored in memory (located in the ventricles of the brain), to be reactivated by recollection, imagination, or the "estimative power" (vis æstimativa), which performs such tasks as recognizing that a predator is dangerous, or that grass is food. In humans, sensible species undergo further refinement (the "abstraction from matter," for example, that Aristotle regards as characteristic of mathematics) and become "intelligible species," the raw materials used by reason.


The consensus, never total, established around Aristotle broke down in the early seventeenth century. The stoutest blow was dealt to it by René Descartes (15961650). With his work the science of the soul begins to divide into two disciplines: a psychology of ideas and a physiology of the nervous system.

The notion of "idea" and the beginnings of an analysis of ideas are put forward in the Meditations (1640). In the Treatise of Man (written 16311633, published in Latin translation 1662), on the other hand, Descartes, following closely the plan of the relevant parts of De Anima, attempts to demonstrate that all the functions hitherto attributed to the souls of animals and plants could be exhaustively accounted for in purely mechanistic terms. The Description of the Human Body (1640s, first published in Latin translation 1662) extends that account to reproduction.

The body is for Descartes a hydraulic machinea connected assemblage of organs whose actions are coordinated by the "animal spirits" (a fluid composed of subtle, fast-moving particles or "corpuscles") that course through the nerves and muscles. Seeing, for a cat, is a sequence of collisions of corpuscles, first of light particles on the nerve-endings in the retina and eventually of the animal spirits with the pineal gland, where they produce "impressions" that in a human body affect the mind to produce sensations of light and color. In human beings alone something more happens. The sight of a rose gives rise to a "mode" or modification of the soul, which for Descartes is a separate, immaterial substance "tightly joined" with the body. If by "seeing" one means 'having a visual sensation', then the cat does not see, only human beings do. Similarly, if "feeling pain" means 'having one's soul modified in the manner we call pain', then animals do not feel pain, only humans do. That consequence of Descartes's dualism excited much controversy from 1650 to 1750, as did the denial of souls to animals.

The human mind is unique. Insofar as psychology is the study of the soul, "animal psychology" is an oxymoron. Psychology comes to devote itself to the study of the operations of the human mindits faculties and the ideas with which they operate. The essence of mind, according to Descartes, is to think. Occurrent thoughts are modes of res cogitans, the "thinking thing," and the "form" of such a mode is what Descartes calls an idea (see Hamilton, Dissertation G). That form can be described in terms of what the idea presents or represents to the mind. Ideas came to be thought of as akin to signs, "representing" concepts or things; whether Descartes and other early users of the term in its new sense regarded them thus is open to question (Yolton, 1984).

Cartesian psychology was not the only option in the seventeenth century. Pierre Gassendi's revival of Epicurean atomism contrasted both with the philosophy of the Schools and with that of his friend and rival Descartes. He retained the notion of an animal soul and considered the human soul to consist effectively of a material soul, similar to those of animals, and an immaterial rational soul (Bloch, p. 368), a view more closely resembling the Aristotelian than the Cartesian, in which the cognitive functions of the sensitive soul are elevated to become part of the single, immaterial human soul.


The Port-Royal Logic (1662) of Antoine Arnauld and Pierre Nicole placed ideas at the center of the study of thought. An idea is simply that which is "in our mind" when we conceive something. To the logical notions of term, proposition, syllogism, and method, there correspond the mental operations of conceiving (an idea), judging, reasoning, and putting arguments in order. Thus the study of language and thought were united into a new discipline at once concerned with the validity of arguments and the nature of the mind.

Cartesian physiology had failed conspicuously to live up to the promises made on its behalf by Descartes. Nicolaus Steno (Observations Anatomiae, 1662) and Thomas Willis (Cerebri Anatomae, 1664) had shown that Descartes's anatomy was grossly mistaken, and in particular that the pineal gland could not possibly have the functions he ascribed to it. Although anatomists in the early eighteenth century continued to map the brain and nervous system, and to make some headway in localizing functions, it is not surprising that philosophers should have taken to a method that did not require detailed knowledge of the "springs" of thought.

In Descartes's Rules for the Direction of the Mind (16261628, first published 1684), the "things" with which the philosopher deals are said to be simple or complex. That distinction, not entirely new, was applied to ideas: Arnauld and Nicole, and Leibniz shortly thereafterboth of them having access to the as yet unpublished rulesapplied that distinction to ideas. Leibniz in particular is, in the 1670s, proposing the analysis of ideas into what he calls "primitive" ideas, not further analyzable. Locke's Essay concerning Human Understanding (1690) deals with the analysis of ideas, or the uncovering of the "original" ideas "from whence all the rest are derived" (p. 286). Those original ideas, few in number, Locke divides into ideas of sense, received from the body, and ideas of reflection, received from the mind.

The analysis and classification of ideas according to their composition from originals provided what could be called their "statics." The "dynamics" was based on the notion of the association of ideas. That one idea might call up another was not at all a new observation. Descartes had taken note of it, and Baruch Spinoza (16321677) adverted to it quite often. Locke's contribution was to make it fundamental to a theory of error. Not all connections among ideas arise from association. Some connections are natural (for example, between the idea of red and that of color). Some are artificial, forged by chance or custom, which can bind together any two ideas, however distant. Association became an important tool. George Berkeley (16851753), for example, explains depth perception by reference to a "habitual or customary" connection between the muscular sensations caused by positioning the eyes so as to maintain a single image of an object and the idea of the distance of that object from the viewer (Essay toward a New Theory of Vision, 1709).

Locke's Essay and the way of ideas were enormously influential through the eighteenth century. Condillac (Étienne Bonnot) in particular devoted his 1754 Traité des sensations (Treatise on sensations) to the study of a "statue" having only one of the five senses, and to the proposition that touch teaches vision how to recognize shapes and distances, the conclusion being that all the various faculties of the souljudgment, reflection, the passionsare nothing other than "transformations" of sensation. (Destutt de Tracy, mentioned below, would later hold that all thought is feeling.) Condillac's claim that touch teaches vision was based in part on descriptions of the experiences of persons blind from birth who recovered their vision, including a famous case described by the London surgeon William Cheselden in 1728. That case seemed to provide an answer to William Molyneux's query to Locke, on whether a person blind from birth would recognize the objects previously known only by touch (see Degenaar).

David Hume (17111776) begins his Treatise (1739) with a distinction between "impressions" (unlike the impressions made by animal spirits on the pineal gland, these are in the mind) and "ideas," the difference being that impressions are, like Locke's "originals," not derived from other ideas. Ideas of substance and (most famously) cause are analyzed in terms of relations among ideas initiated by association (between resembling ideas) and confirmed into habit. The last concerted attempt to follow the way of ideas was the "ideology" of A. L. C. Destutt de Tracy, presented in his Idéologie of 1804. The political importance of Lockeanism is hinted at by noting that Destutt de Tracy was a deputy in the Estates General of 1789, who was arrested under the Terror but survived, and had his commentary on Montesquieu's Spirit of the Laws censored by the government of Napoleon in 1806.


Eighteenth-century materialism was quite distinct from what is now called "physicalism." The physicalist holds that the only properties possessed by concrete substances are those imputed to them by established physical theory. The eighteenth-century materialist, in agreement with the physicalist, denies that the mind is immaterial, but typically sensibility (the basic mental property, as in Condillac and Destutt de Tracy) is treated as a property additional to the basic physical properties of matter, and not reducible to them.

Many eighteenth-century philosophers, among them Denis Diderot (17131784) and Pierre Louis Moreau de Maupertuis, attributed a primitive sensibility to small particles of matter, "organic molecules" as Georges Louis Leclerc Buffon called them, from which the more complex capacities of animals and humans are derived. Julien Offroy de La Mettrie is another instance. The title of his best-known work, first published in 1747 (with a false date of 1748), is L'homme machine (Man a machine), but in the machine every fiber is endowed with a natural oscillation, proved by, among many other experiments, the continued beating of the hearts of animals after they are removed (1751/1987, 1:104105; see also L'homme plus que machine, 2:159). In the Rêve d'Alembert (1769; Dream of d'Alembert), Diderot, following the physician Théophile de Bordeu, likens the organism to a swarm of beesthe "organic molecules." Consciousness and will become "statistical" phenomena, like the changing sentiments of a crowd, a view reminiscent of certain much more recent theories of mental activity.

The end of the early modern period witnessed the discovery by Alessandro Volta (17451827) and Luigi Galvani (17371798) that nerves conduct electricity. That and the comparative studies of late eighteenth- and early nineteenth-century anatomists, which established, among other things, the independent role of the spinal cord in reflex actions, laid the basis for a neuroscience recognizably like that of today.

Willis, in his "Anatomy," writes that he "addicted my self to the opening of Heads especially, and of every kind" not only in order to found a "more certain Physiologie," but also a "Pathologie of the brain and nervous Stock" ("Anatomy," p. 53; quoted in Frank, p. 108). He went so far as to regard every disease as neural in origin; the resulting "neural pathology" had adherents even in the mid-nineteenth century. At the very end of the period, Philippe Pinel, famous for supposedly setting free the inmates of the Salpêtrière asylum in Paris during the Terror (Weiner, p. 333), published his Traitémédico-philosophique sur l'aliénation mentale (1801; Medico-philosophical treatise on mental alienation), one of the founding documents of the new discipline of psychiatry.

See also Aristotelianism ; Berkeley, George ; Cartesianism ; Descartes, René ; Gassendi, Pierre ; Hume, David ; La Mettrie, Julien Offroy de ; Leibniz, Gottfried Wilhelm ; Locke, John ; Madness and Melancholy ; Mechanism ; Medicine ; Spinoza, Baruch .


Primary Sources

Bayle, Pierre. Dictionnaire historique et critique. 3rd ed. Rotterdam, 1720. 1st ed. Rotterdam, 1697.

La Mettrie, Julien Offroy de. Oeuvres philosophiques. 2 vol. Paris, 1987. 1st ed. London, 1751; L'homme machine and L'homme plus que machine were first published in 1748.

Locke, John. An Essay concerning Human Understanding. Edited by Peter H. Nidditch. Oxford, 1975. 1st ed. 1690.

Secondary Sources

Bloch, Olivier René. La philosophie de Gassendi: Nominalisme, matérialisme et métaphysique. The Hague, 1971.

Clarke, Edwin, and L. S. Jacyna. Nineteenth-Century Origins of Neuroscientific Concepts. Berkeley, 1987.

Degenaar, Marjolein. Molyneux's Problem: Three Centuries of Discussion on the Perception of Forms. Translated by Michael J. Collins. The Hague, 1996.

Hamilton, Sir William. "Editor's supplementary dissertations." In The Works of Thomas Reid, D. D., edited by Sir William Hamilton. 7th ed. Glasgow, 1872.

Porter, Roy. "Medical Science and Human Science in the Enlightenment." In Inventing Human Science: Eighteenth-Century Domains, edited by Christopher Fox, Roy Porter, Robert Wokler, pp. 5387. Berkeley, 1995.

Roger, Jacques. The Life Sciences in Eighteenth-Century French Thought. Translated by Robert Ellrich. Stanford, 1998.

Rousseau, G. S., ed. The Languages of Psyche. Mind and Body in Enlightenment Thought: Clark Library Lectures, 19851986. Berkeley, 1990. See, in particular, Frank, Robert G., Jr. "Thomas Willis and His Circle: Brain and Mind in Seventeenth-Century Medicine" and Weiner, Dora B. "Mind and Body in the Clinic: Philippe Pinel, Alexander Crichton, Dominique Esquirol, and the Birth of Psychiatry."

Wellman, Kathleen Anne. La Mettrie: Medicine, Philosophy, and Enlightenment. Durham, 1992.

Yolton, John W. Perceptual Acquaintance: From Descartes to Reid. Minneapolis, 1984.

. Thinking Matter: Materialism in Eighteenth-Century Britain. Minneapolis, 1983.

Dennis Des Chene

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Psychology is a broad-ranging discipline concerned with human mind and emotion, experience and behavior, and personality development and disorder. It goes back at least to the pre-Socratics of ancient Greece, and has always been a central topic in philosophy. It has also been a concern of many religious thinkers, perhaps especially in the Christian and Buddhist traditions. However, psychology as a distinct autonomous discipline only goes back to the nineteenth century.

After considering the implications for theology of the emergence of psychology as a distinct discipline, three different strands in the relationship between psychology and religion will be examined. First there are theological issues raised by the approach to human nature found within general psychology. Second, there is the investigation of religion using the methods and theories of psychology. Finally, there is the possibility of a psychological contribution to a broad range of topics in theology.

Psychology as science

Modern psychology is self-consciously scientific. It accepted the natural sciences as representing the paradigm of rational inquiry and has sought to mould itself in their image. That has often led to giving priority to mechanistic and materialistic approaches, and to experimental method and repeatable observations.

One key problem for psychology has been deciding what to use as its data. Much psychology is based on self-report data, which includes people reporting their own thought processes and experiences, describing their attitudes or behavior, or completing questionnaires about themselves. Questionnaire research has become the stock methodology of much psychology; it is an easy method to use and has probably been overused. Other self-report data, such as the clinical data collected by Sigmund Freud (18561958), may be rich, but there are serious questions about its dependability. One problem with self-report data is that many people are not reliable observers of themselves; the other is that people may not choose to report accurately what they know.

Psychology has also made much use of observable behavior and performance, including observations of how people perform cognitive tasks and how they interact with other people. There was a period in the early twentieth century when psychology imagined that it could base itself entirely on the observation of behavior, and abandon any attempt to study the human mind. However, behaviorism, in its strict form, did not last, and mind was readmitted under the heading of cognition. It proved impossible to study even conditioning in rats without inferring mental processes such as expectations. Also, psychologists became increasingly sophisticated in the use of task performance to infer cognitive processes. In this more emancipated climate, self-report data was re-admitted, but used cautiously.

The scientific movement out of which modern psychology arose was explicitly secular in that it deliberately avoided making any religious assumptions. The relation of modern secular psychology to the more explicitly religious psychological reflection that preceded it is a complex matter. Some would emphasize the parallelism between the two. Even though psychology appears to be secular, it can be argued that it is much indebted to its religious past and has often recycled theological ideas in apparently secular form. For example, it has been argued that the concept of original sin lies just below the surface of Freud's avowedly secular psychology.

In contrast, John Milbank has robustly argued that modern social theory, because it is avowedly secular and has no place for God, should be regarded as antitheological and inconsistent with Christian thought. The same might also be said about modern psychology. Against that, however, it could be argued that psychology has become religiously neutral and atheological, capable of being combined either with religious or secular worldviews. The model of science that guided modern psychology in the nineteenth century would now be widely regarded as over-restrictive. However, psychology has gradually become broader, more pluralistic, and more flexible ideologically (i.e., more postmodern).

Psychological approaches to human nature

Psychology contains general assumptions about human nature, and a key issue that arises at the interface of psychology and theology is how compatible are their respective views of human nature. Given the breadth of psychology as a discipline, it is not surprising that it contains a variety of such models, ranging from the biological to the social. Psychology makes use of the radically different methodologies of the social and biological sciences within the same discipline. Not surprisingly, that means that psychology tends to fragment, but it is important that there should be a discipline that tries to hold together these different approaches to the human person. People are both biological and social creatures, and no discipline that ignored one or the other could hope to understand human nature adequately.

There is a tendency for psychology to emphasize the biological aspects of human nature and for theology to emphasize the social and relational aspects. However, a polarized debate should be avoided. An adequate psychology needs to be social as well as biological. Equally, there is no reason why theology should be reticent about the biological aspects of human nature. It is part of the Judeo-Christian tradition, especially in the Old Testament, that human beings come from the "dust" and have much in common with the "beasts." There has been a growing recognition that both theology and psychology in their different ways emphasize the psychosomatic unity of human nature. Theology and psychology both need to hold together the biological and the social aspects of human nature, and could learn from each other's attempts to do so.

One strand of biological psychology seeks to understand human characteristics in terms of their evolutionary origins. There were precursors of this in the sociobiology of Edward O. Wilson (b. 1929), Richard Dawkins (b. 1941), and others; their approach has now been extended into evolutionary psychology. A key issue for theology is how strongly reductionist a form evolutionary psychology takes. There is no theological objection to exploring the evolutionary origins of particular human abilities and characteristics, and this has been fruitful in many areas, such as linguistic ability. Problems only arise when it is suggested that the evolutionary approach can explain everything, or that human characteristics are nothing more than the products of their evolutionary origins. Fortunately, cautious research-based approaches to evolutionary psychology are available.

The other important strand of biological psychology is concerned with the brain. Research in neuropsychology has been especially fruitful and has demonstrated close links between cognitive functions and brain activity. The key issue for theology is how this information should be interpreted, which is essentially a philosophical problem. There have been suggestions that the mind and brain are identical, or that mind is an epiphenomenon of the physical brain of no real significance. However, there is no need for psychology to take the kind of strong reductionist approach represented by the biologist Francis Crick (b. 1916), who in 1994 described people as "nothing but a pack of neurons" (p. 3).

Strong forms of social constructionism can be equally reductionist. Human concepts are, of course, the product of particular cultures, and in some respects they are contingent and could be conceptualized otherwise. Further, concepts are psychologically influential, and human experience and behavior is much influenced by how people conceptualize their world. However, there is no need for this to be linked to a nonrealist claim that there is no reality to what concepts represent beyond cultural conventions, or that social constructs completely determine social behavior.

A final area of psychology that carries strong assumptions about human nature is the computer modeling of human intelligence. The analogy between computers and the human mind has been fruitful scientifically and has given cognitive psychology much of its current rigor. However, the indications are that human beings and computers function in such different ways that the analogy between them should not be pressed too far. There is no warrant for asserting that all human functions can be captured in computer form, or that the human mind is nothing but a computer program.

Psychology of religion

The psychology of religion was an active area of psychology in the early days of the discipline and, after a period of decline, has regained some of its former vigor. To realize its potential, it needs to maintain close links with general psychology and apply the most promising advances; generate a broad theoretical approach to religion and relate data to clear research hypotheses; use a range of different methodologies and not rely too much on questionnaire data; and explore the practical applications of psychology for religious life.

The issues about reductionism that arise in general psychology recur in the psychology of religion and can be illustrated in connection with religious experience. There is growing interest in the brain processes involved in religious experience. An example is the research of Eugene d'Aquili and Andrew Newberg, who have analyzed the holistic and causal elements of some types of religious experience and tried to identify their neural substrates. However, whatever progress is made in discovering how the brain is involved in religious experience, there is no reason to conclude that because the brain is involved religious experience has nothing to do with God.

There has also been much interest in the social constructionist approach to religious experience. How people conceptualize experience in religious terms is clearly influenced by the various faith traditions, and may explain the different emphases in religious experiences within different faith traditions, despite the common elements that can also be found. Some have suggested that reports of religious experience are entirely the product of such cultural learning, but there is no basis for asserting that religious experience is nothing more than learning to use a particular set of constructs. Broad-brush social constuctionism is being replaced by sophisticated theory and research on the specific cognitive processes involved in religious modes of understanding.

When particular examples of religious experiences are studied, it becomes particularly clear that it is valuable to combine a variety of psychological approaches. This can be illustrated in relation to glossolalia (speaking in tongues), the best investigated of the charismatic phenomena. There is evidence for an element of social learning, in that people benefit from seeing other people speak in tongues, and get better at it with practice. However, the dissociation of semantics from speech production that occurs in glossolalia suggests an unusual mode of cognitive functioning for which there must be a neurological substrate. There is no incompatibility between approaches from social psychology and from cognitive neuroscience, nor is either of them incompatible with a religious account of the role of the Holy Spirit in glossolalia.

There is currently a growing interest in the evolutionary approach to religion, though as yet it is largely speculative. The capacity for religious experience may well be related to the distinctive capacity for self-consciousness of human beings. It can also be seen as having advantages in natural selection terms through the promotion of social cohesion, moral behavior, mental health, and so on. This is supported by the fact that there is growing evidence that religion is positively associated with good personal adjustment.

The link between religion and personal adjustment becomes clearer if religious people are subdivided, for example into those for whom religion is intrinsic or central to their lives (who have good mental health) and those for whom it is extrinsic or serves other goals (who have poor mental health). Though it is always difficult to move with confidence from correlations to casual conclusions, the mechanisms by which religion might promote good adjustment are becoming clear and include the therapeutic value of religious practices and the support provided by the religious community.

Though religious experience illustrates the breadth of the psychological approach needed in studying religion, it is important to remember the multifaceted nature of religion. There is an equally fruitful psychology of religious beliefs and observances. Psychology has often found it fruitful to study how people differ from one another, and how they develop and change. Both have been central to the psychology of religion.

Psychology and theology

Finally, there can be psychological contributions to theology, although these have not been very fully explored as of 2002. For example, the story of the "fall" in Genesis and the doctrine of original sin invite psychological elucidation. Though the story of the "fall" is widely taken by theologians as making an ontological point about human sinfulness, it can equally well be taken as indicating, in narrative form, the gradual evolutionary development of self-conscious cognitive discrimination, represented by the "knowledge of good and evil." This would be, in a sense, a fall upwards, but it would imply a new capacity to do wrong deliberately, that is, to sin. In addition, emerging self-consciousness would lead to a new awareness of human limitations and fallibility, which would permit human awareness of sinfulness and of separation from God.

Eschatology invites elucidation in terms of the psychology of hope. Though there has been much interest in the relation between cosmological predictions and theological eschatology, it would be a misreading of eschatology to see it as solely concerned with such objective predictions. Eschatology is concerned with a good future that is a gift of God, not just with survival of the universe, and also with an attitude of hope in the present, not just with predictions about the future. Psychology can help to elucidate the nature of eschatological hope. It seems to be not just a matter of optimism (making positive predictions about the future), but a hopeful attitude that can be sustained even when there is little basis for optimism.

There are many theological topics that can be complemented by a psychological approach that does not compete with or displace the theological one. For example, a theology of grace can be complemented by a psychological account of how the benefits of grace work themselves out at a human level. Similarly, a theology of prayer can be complemented by a psychological account of how the activity of prayer helps to transform those who participate in it. The act of thanksgiving, for example, involves a reappraisal, both of the evaluation of experiences as positive or negative, and of the role of God in causal attributions.

See also Artificial Intelligence; Behaviorism; Evolutionary Psychology; Experience, Religious: Cognitive and Neurophysiological Aspects; Freud, Sigmund; Mind-brain Interaction; Neurophysiology; Neurosciences; Psychology of Religion; Self


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fraser watts

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For much of its 125-year history, psychology, the study of human behavior, could not find a place for death and dying among the topics that it considered worthy of scientific attention. Although psychology was derived from philosophy, a system that gives death a central role in shaping human thought and conduct, early on there was a schism between those who wanted to study behavior from an experimental, physiological perspective and those who wanted to keep a broader, person-based focus. In Europe during the late 1800s, experimental psychology was advanced by such pioneers as Wilhelm Wundt, Francis Galton, and Alfred Binet, and in the United States by E. L. Thorndike, G. Stanley Hall, James McKeen Cattell, and John Dewey. A more encompassing, holistic approach was advanced in Europe by Sigmund Freud and in America by William James.

With late-nineteenth-century science dominated by Charles Darwin's theory of evolution, it was perhaps inevitable that the fledgling science of psychology steered itself toward the experimental, psychophysiological side of investigation and away from philosophy. Although there were voices in the field hinting at the importance of death for understanding human behavior, psychology as a whole paid little attention.

Logical positivism, a method of inquiry that rejects transcendental metaphysics and requires as proof verifiable consequences in experience, held center stage in psychology until the events of World War II fundamentally changed the way psychologists considered their task. Many of the early experimental theories of behavior emphasized evolutionary (genetic) determinism. However, nothing in the psychologist's laboratory manual could predict or explain the wholesale human destruction of two world wars in fewer than thirty years. Science the savior turned out to be the specter of death in the guise of Nazi Germany and the atomic bomb.

In the wake of World War II, psychology turned its attention to social and organizational behavior, as well as to explanations of racism and violence in the development of malignant personality patterns. It was again willing to consider philosophical approaches to behavior that emphasized the whole person. Logical positivism was eclipsed by existential and humanistic philosophies that grappled with the nature of humanity and the meaning of behavior.

In this context, psychology's first organized approach to death was a symposium titled "The Concept of Death and Its Relation to Behavior," chaired by clinical psychologist Herman Feifel and presented at the 1956 annual meeting of the American Psychological Association in Chicago. The symposium served as the basis for the 1959 book The Meaning of Death, edited by Feifel, which is widely recognized as the single most important influence in galvanizing what has since become the multidisciplinary field of thanatology (the study of death, dying, and bereavement).

During the two decades that followed publication of Feifel's book, psychologists began to fully participate in the thanatological community by making important contributions to theory, research, education, and service delivery. Empirical and clinical advances were made in understanding how people construct their ideas and attitudes about death, how ideas about death change from childhood through old age, the nature and meaning of death anxiety, the biological basis of attachment and grieving, and why people commit suicide. Psychologists such as Daniel Leviton and Robert Kastenbaum helped spearhead the death education movement, and the latter built one of the first university centers devoted to the study of death at Wayne State University in Detroit, Michigan. Two of the premier research journals devoted to this topic area were created by psychologists: Omega: The Journal of Death and Dying edited by Robert Kastenbaum, and Death Education, now called Death Studies, edited by Hannelore Wass.

The last two decades of the twentieth century saw a maturing of the field of thanatology, the role played by psychologists in shaping the future of death studies, and the treatment of dying and bereaved persons. During this time psychologists were at the forefront in research on death attitudes and death anxiety; coping with life-threatening illnesses such as cancer, heart disease, and AIDS; grief and bereavement; and the study of suicide. Psychologists helped build and staff hospices for terminally ill patients. Many colleges and universities hired psychologists who made death studies a major focus of their work as part of an expansion of research and coursework in thanatology for students in developmental, clinical, counseling, and school psychology programs.

Empirical and Clinical Findings

From its inception, thanatology has been a multi-disciplinary field encompassing anthropology, education, medicine, nursing, philosophy, psychiatry, religion, social work, sociology, the arts, and the humanities. In contrast to this ecumenical trend, research on death attitudes and death anxiety has been conducted mostly by psychologists. Perhaps this is why the literature has shown a strong focus on methodological issues rather than broader sociocultural and applied concerns. By 1995 there were more than 1,000 published studies in this field that addressed diverse subjects, including children, adolescents, adults, the elderly, and the mentally ill. Almost all of these studies involved descriptive, atheoretical, single-assessment designs and used self-report questionnaires. In spite of the limitations inherent in these studies, four themes have emerged from their findings:

  1. Most people think about death to some extent and report some fear of death, but only a small subset exhibit a strong preoccupation with death or fear of death.
  2. Women consistently report more fear of death than men, but the difference is typically minor to moderate.
  3. Fear of death does not increase with age among most people.
  4. When considering their own death, people are more concerned with potential pain, help-lessness, dependency, and the well-being of loved ones than with their own demise.

Studies have also demonstrated that fear of death is not a unidimensional variable. Various subcomponents are evident in fear of a painful or unpleasant afterlife, fear of the unknown, and fear of a loss of dignity or individuality. In addition, some research has shown that fear of death may take different forms on the conscious and unconscious levels. For example, low levels of self-reported death anxiety may be an outright aversion and avoidance at an unconscious level.

Death possesses many meanings for people and is an important psychological element for all persons, not just the elderly, dying persons, and those facing potential death in their daily activities (e.g., military and police). People think about death and experience the deaths of others throughout life. Adult conceptions of death can be quite complex and involve multiple abstractions, among them the concepts of futurity, inevitability, temporal uncertainty, universality, personal inclusion, and permanence. As humans develop from early childhood into adulthood, their ability to think abstractly also increases. Research has confirmed that among children and adolescents, comprehension of death is related to general levels of cognitive development and personal experiences with death-related phenomena.

The pioneering work of the Hungarian psychologist Maria Nagy identified three stages of development in children's ideas about death. In children from three to five years old she found great curiosity about death and a widespread view of death as a separation where the dead are not as alive as the rest of us but can come back to normal living status. From ages five to nine children begin to understand that death is final but they persist in believing that one might avoid it. Death also becomes personified at this age. From age nine into adulthood there is recognition of death as personal, universal, final, and inevitable.

Research on the death attitudes of children and adolescents demonstrate that they must not be shielded from knowledge of death and should be included in discussions about death at appropriate times. Even the youngest children are aware of separation and its threat to their well being. Young people are inquisitive about death. Adults who exclude children from death-related conversations and experiences do them a disservice by removing them from important sources of information and thus reinforcing anxiety and fear. Adults who wish to participate in educating their children about death must be aware of their own attitudes and values, be prepared to share their feelings and experiences, and serve as models for a healthy appreciation of the importance of death.

Treatment of the Dying and Bereaved

Medical advances have extended the human life span, yet created a growing population of persons (particularly the elderly) who die with chronic diseases. Too often the focus of professionals has been on the physical disease rather than the experiences of the victims. Both clinical and research findings underscore that dying is not just a biological process but also a psychological one. There is an essential need for open and honest communication between the dying person, health-care providers, family, and friends.

The attitudes and fears of caregivers strongly influence the way in which they view and treat the dying and bereaved. Most dying persons and their families want to be apprised of the processes of death, communicate about death and its consequences, and be included in decision-making as it applies to treatment and end-of-life issues. Unless health-care providers can become aware of their own feelings and attitudes, receive education about dying and grief, and become comfortable with the knowledge of death as a multifaceted process that has many derivatives and outcomes, their patients will often be ill-served or even harmed.

The psychiatrist Elisabeth Kübler-Ross conceived a five-stage model of dying and grief that has helped to increase death awareness in the general public and has spawned numerous research investigations. She proposed that as individuals respond to awareness of impending death (their own or that of a loved one), they move through stages of denial, anger, bargaining, depression, and acceptance.

Empirical and clinical investigations inform us that grief unfolds in many different ways and demonstrates not weakness but rather a necessary and deep human need most of us have in reacting to the loss of our own life and that of a loved one. Hard data do not support the existence of stages or schedules through which all persons move as they experience and respond to death. For example, studies of Kübler-Ross's model have shown a simultaneity, omission, or reversal of stages in some individuals.

Because of a lack of precise clinical criteria, healthy and unhealthy grief can be difficult to distinguish. Hence practitioners must be cautious in encouraging survivors to abandon grief prematurely or to wallow in it. They must be alert to signs of personal denial, avoidance, or antipathy among the dying and bereaved so that meaningful interventions can be considered early enough to have the greatest positive impact.

Current and Future Directions

Among the areas of current interest and importance to psychologists are the development of comprehensive theories of dying and bereavement; studies of death and dying among children; theory-based, experimental, longitudinal, and cross-cultural investigations of how death attitudes are related to diverse human behaviors; and development of empirically-validated models and methods for treating the dying and bereaved.

Although thanatology is still waiting for a compelling, realistic framework for understanding death, progress is being made by psychologists in conceptualizing dying and bereavement. People in the field have moved away from viewing grief as a series of predictable stages to seeing it from a task-based perspective. Charles Corr identified four dimensions of tasks: physical, psychological, social, and spiritual. Kenneth Doka suggested a five-phase model of life-threatening illness: prediagnostic, acute, chronic, terminal, and recovery. Clinical psychologist Therese Rando advanced the concept of anticipatory grief to include not only one's reactions to an impending death but also all of the losses experienced throughout one's life. Robert Neimeyer, clinical psychologist, and colleagues have developed their view of bereavement as a task of meaning reconstruction. Robert Kastenbaum has argued for a life-span-developmental approach to death and dying that incorporates a biopsychosocial perspective, stressing an awareness of what anthropologists call etic and emic frames of reference; that is, viewing death from the outside (as observer) and inside (from the point of view of the dying person). He has drawn attention to deathbed scenes as a way of developing a more complete understanding of dying at what is arguably the single most critical point in the process. The social psychologists Tom Pyszczynski, Jeff Greenberg, and Sheldon Solomon applied terror management theory to the fear of death. They argued that a wide variety of behaviors, many of them seemingly unrelated to death, guard against conscious and unconscious fear of personal death.

Since 1956 psychology has moved from its original ostrich approach to death to a recognition of death studies as among the most important in the field. The bounty of books and hundreds of research articles published each year portend a continued flourishing of thanatology in the twenty-first century.

See also: Anthropological Perspective; Anxiety and Fear; Death Education; Dying, Process of; Feifel, Herman; KÜbler-Ross, Elisabeth; Sociology; Stage Theory; Terror Management Theory


Corr, Charles A., Kenneth J. Doka, and Robert Kastenbaum. "Dying and Its Interpreters: A Review of Selected Literature and Some Comments on the State of the Field." Omega: The Journal of Death and Dying. 39 (1999):239259.

Feifel, Herman. "Psychology and Death: Meaningful Rediscovery." American Psychologist 45 (1990):537543.

Feifel, Herman. The Meaning of Death. New York: Mc-Graw-Hill, 1959.

Freud, Sigmund. Beyond the Pleasure Principle, edited and translated by James Strachey. New York: Norton, 1975.

Hall, G. Stanley. "Thanatophobia and Immortality." American Journal of Psychology 26 (1915):550613.

James, William. The Varieties of Religious Experience. New York: Modern Library, 1994.

Kastenbaum, Robert. The Psychology of Death, 3rd edition. New York: Springer, 2000.

Kübler-Ross, Elisabeth. On Death and Dying. London: Macmillan, 1969.

Nagy, Maria. "The Child's Theories Concerning Death." Journal of Genetic Psychology 73 (1948):327.

Neimeyer, Robert A., ed. Meaning Reconstruction and the Experience of Loss. Washington, DC: American Psychological Association, 2001.

Neimeyer, Robert A., and David Van Brunt. "Death Anxiety." In Hannelore Wass and Robert A. Neimeyer eds., Dying: Facing the Facts, 3rd edition. Philadelphia: Taylor & Francis, 1995.

Pyszczynski, Tom, Jeff Greenberg, and Sheldon Solomon. "A Dual-Process Model of Defense against Conscious and Unconscious Death-Related Thoughts: An Extension of Terror Management Theory." Psychological Review 106 (1999):835845.

Rando, Therese A., ed. Loss and Anticipatory Grief. Lexington, MA: Lexington Books, 1986.

Shneidman, Edwin S. The Suicidal Mind. New York: Oxford University Press, 1996.

Strack, Stephen, ed. Death and the Quest for Meaning. Northvale, NJ: Jason Aronson, 1997.

Wass, Hannelore, and Robert A. Neimeyer, eds. Dying: Facing the Facts, 3rd edition. Philadelphia: Taylor & Francis, 1995.



See Deathbed Visions and Escorts.

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334. Psychology

See also 28. ATTITUDES ; 41. BEHAVIOR ; 129. DREAMS ; 224. INSANITY ; 254. MANIAS ; 279. MOODS ; 311. PHILE, -PHILIA, -PHILY ; 313. PHOBIAS .

the study or treatment of mental diseases, especially in their relation to legal problems. alienist, n.
the simultaneous presence in one person of positive and negative feelings towards a person, object, etc.; coexistence of mixed feelings.
the projection of ones own characteristics onto another person. automorphic, adj.
the theory or doctrine that observed behavior provides the only valid data of psychology. behaviorist, n., adj. behavioristic, adj.
bisexualism, bisexuality
the state of being sexually responsive or attracted to members of both sexes. See also 51. BODY, HUMAN . bisexual, adj.
Gestalt Psychology. the basic precept that psychological phenomena are the result of gestalts functioning separately or in relation to one another, as contrasted with individual elements, such as reflexes or sensations. configurationist, n., configurational, configurative, adj.
Medicine. a frenzied, sleepless delirium accompanied by wild and frightening hallucinations. Also corybantiasm .
a method of self-help stressing autosuggestion, introduced into America by the French psychotherapist Emile Coué c. 1920 and featuring the slogan Every day in every way I am getting better and better.
cryptesthesia, cryptaesthesia
the innate ability to be clairvoyant, as in parapsychological experiments. cryptesthetic, adj.
a mode of thinking directed away from reality and toward fantasy without cognizance of ordinary rules of logic. dereistic, adj.
a condition characterized by a lack of sympathy or passion. dyspathic, adj.
extreme anxiety and depression accompanied by obsession. dysthymic, adj.
the study of mental imagery.
theory and practice of Sigmund Freud, especially in the area of neuroses, their causes and treatment. Freudian, n., adj.
extreme or abnormal sensitivity, as to criticism. hypersensitive, adj.
the process of producing a hypnotic condition or state of hypnosis. hypnogenetic, adj.
the treatment of disease and illness by hypnosis. hypnotherapist, n.
1. the science dealing with the induction of hypnosis, especially for therapeutic purposes.
2. the act of inducing hypnosis; hypnotizing.
3. hypnosis. hypnotist , n. hypnotistic , adj.
hyponoia, hyponea
a state of dulled mental activity or decrease in the function of thought. Also called hypopsychosis .
a condition of extreme excitement characterized by emotional disturbance, sensory and motor derangement and sometimes the simulation of organic disorders. hysterie , n. hysteric, hysterical, adj.
1. the process of inducing hysteria.
2. the onset of hysteria. hysterogenic, adj.
the condition of one who is not a child acting abnormally childlike. infantility, n. infantilistic, adj.
the belief that psychology must be derived from introspective data. introspectionist, n. introspective, adj.
psychotherapy that tries to find for the patient the aim and meaning of his own life as a human being and does not stress the medical aspect of mental health.
1. a speculation dealing systematically with concepts extending beyond the present limits of psychology as an empirical science.
2. a conception in psychoanalytic theory of mental processes involving causal relations, structural placement, and functional value. metapsychological, adj.
the speech of a psychotic containing new combinations of words unknown to a hearer. See also 382. SPEECH .
any of a large variety of mental or psychic disorders, exhibiting a range of mental or physical symptoms, as anxiety, phobias, compulsions, and tics. neurotic, n., adj.
a neurotic condition; psychoneurosis.
the process of correcting bodily or mental distortion. orthotic, adj.
1. the pervasion of all conduct and experience with sexual emotions.
2. the theory that regards all desire and interest as derived from sex instinct. Also pansexuality. pansexualist, n.
paralogia, paralogy
a reasoning disorder characterized by inappropriate responses to questions and illusiorial or delusional speech. paralogical, adj.
the process whereby a person fails to complete his intention, as by the mislaying of objects, thought to be the result of a conflict between unconscious and conscious intention.
the branch of psychology that studies psychic phenomena, as telepathy, clairvoyance, extrasensory perception, and the like. parapsychological, adj.
the branch of psychology concerned with description and comparison. phrenographic, adj.
mental or psychic pain.
the method developed by Freud and others for treating neuroses and some other disorders of the mind. psychoanalyst, n. psychoanalytic, psychoanalytical, adj.
the study of the relations or interrelations between body and mind, especially as exhibited in the nervous system. psychobiologist, n. psychobiologic, psychobiological, adj.
1. the science or art of making a personality evaluation.
2. the diagnosis of a mental disorder. psychodiagnostician, n. psychodiagnostic, adj.
the systematic study of personality in terms of past and present experiences in relation to motivation. psychodynamic, adj.
a theory of the development of the mind. psychogonic, psychogonical, adj.
an attack of mental inertia and hopelessness following a period of elation, especially in sufferers from neurosis. psycholeptic, adj.
the theory that emphasizes psychological conceptions in other fields outside of psychology, as philosophy and history.
the science that studies the mind and mental processes, feelings, and desires. psychologist, n. psychologic, psychological, adj.
psychometrics, psychometry
the measurement of mental traits, abilities, and processes. psychometrist, n. psychometric, adj.
1. the alleged ability to divine the characteristics of an object or a person connected with it by touching the object.
2. the determination of the duration and intensity of processes of the mind. psychometer, n. psychometric, psychometrical, adj.
Medicine. the science of the diseases of the mind. psychopathologist, psychopathist, n. psychopathologie, psychopathological, adj.
a mental disorder. psychopath, n. psychopathic, adj.
the study of drugs that effect emotional and mental States. psychopharmacologic, psychopharmacological, adj.
an abnormal fear of the mind.
the branch of psychology that studies the relationships between physical stimuli and resulting sensations and mental states. psychophysicist, n. psychophysie, psychophysical, adj.
1. the study of the circumstances under which mental processes occur.
2. the theory that conscious states are made up of elements capable of separating and joining without loss of essential identity. psychostatic, psychostatical, adj.
the science or method of treating psychological abnormalities and disorders by psychological techniques, especially by psychoanalysis, group therapy, or consultation. psychotherapist, n. psychotherapeutic, adj.
a mental condition marked by childish or infantile behavior. puerility, n.
the scientific study of psychological reactions. reactologist, n. reactological, adj.
the study of behavior and its interpretation according to a concept that regards behavior as a combination of simple and complex reflexes. reflexologist, n. reflexological, adj.
a mild form of schizophrenia, characterized by withdrawal, inversion, etc. schizothyme, n. schizothymic, adj.
abnormally rapid mental activity.
a communication between minds by some nontechnological means other than sensory perception. telepathist, n. telepathic, adj.
transsexualism, transsexuality
the psychological phenomenon of a person identifying with the opposite sex, sometimes to the extent of undergoing surgery for change of sex. transsexual, n., adj.
1. any abnormal condition, either pathological or psychological, caused by wound or injury, either physical or psychological.
2. the trauma, wound, or injury itself. traumatic, adj.
a form of insanity or mental disorder in which the sufferer imagines that he is an animal. zoanthropic, adj.
a form of hallucination in which the sufferer imagines he sees animals. Also called zooscopy .

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psychology, science or study of the thought processes and behavior of humans and other animals in their interaction with the environment. Psychologists study processes of sense perception, thinking, learning, cognition, emotions and motivations, personality, abnormal behavior, interactions between individuals, and interactions with the environment. The field is closely allied with such disciplines as anthropology and sociology in its concerns with social and environmental influences on behavior; physics in its treatment of vision, hearing, and touch; and biology in the study of the physiological basis of behavior. In its earliest speculative period, psychological study was chiefly embodied in philosophical and theological discussions of the soul.

Development of Modern Psychology

The De anima of Aristotle is considered the first monument of psychology as such, centered around the belief that the heart was the basis for mental activity. The foundations of modern psychology were laid by 17th-century philosopher Thomas Hobbes, who argued that scientific causes could be established for every sort of phenomenon through deductive reasoning. The mind-body theories of Rene Descartes, Baruch Spinoza, and G. W. Leibniz were equally crucial in the development of modern psychology, where the human mind's relation to the body and its actions have been significant topics of debate.

In England the empirical method employed in modern psychological study originated in the work of John Locke, George Berkeley, Thomas Reid, and David Hume. David Hartley, James Mill, John Stuart Mill, and Alexander Bain stressed the relation of physiology to psychology, an important development in the scientific techniques of modern psychology. Important contributions were made in the physiological understanding of human psychology by French philosopher Condillac, F. J. Gall, the German founder of phrenology, and French surgeon Paul Broca, who localized speech centers in the brain.

In the 19th cent., the laboratory work of Ernst Heinrich Weber, Gustave Fechner, Wilhelm Wundt, Hermann von Helmholtz, and Edward Titchener helped to establish psychology as a scientific discipline—both through the use of the scientific method of research, and in the belief that mental processes could be quantified with careful research techniques. The principle of evolution, stemming from Charles Darwin's theory of natural selection, gave rise to what became known as dynamic psychology. The new approach, presented by American psychologist William James in his Principles of Psychology (1890), looked at consciousness as an evolutionary process.

Out of the new orientation in psychology grew the clinical experiments in hysteria and hypnotism carried on by J. M. Charcot and Pierre Janet in France. Sigmund Freud, in his influential theory of the unconscious, gave a new direction to psychology and laid the groundwork for the psychoanalytic model. Freudian theory took psychology into such fields as education, anthropology, and medicine, and Freudian research methods became the foundations of clinical psychology.

The behaviorism of American psychologist John B. Watson was highly influential in the 1920s and 30s, with its suggestion that psychology should concern itself solely with sensory stimuli and behavioral reaction. Behaviorism has been important in modern psychology, particularly through the work of B. F. Skinner since the 1930s.

Equally important was the development of Gestalt psychology by German psychologists Kurt Koffka, Wolfgang Köhler, and Max Wertheimer. Gestalt theory contended that the task of psychology was to study human thought and behavior as a whole, rather than breaking it down into isolated instances of stimulus and response.

Another influential school of psychology was developed in the 1950s and 60s by Abraham Maslow and Carl Rogers. Their humanistic theory asserts that people make rational, conscious decisions regarding their lives, and optimistically suggests that individuals tend to reach toward their greatest potential.

Modern Psychology

Modern psychology is divided into several subdisciplines, each based on differing models of behavior and mental processes. Psychologists work in a number of different settings, including universities and colleges, primary and secondary schools, government agencies, private industry, hospitals, clinics, and private practices. Recent years have seen a rise in the significance of applied psychology—as can be seen from the areas contemporary psychologists concern themselves with—with an attendant decline in the importance of psychology in academia. In the United States, clinical psychology has become a significant focus of the discipline, largely separate from psychological research. Clinical psychologists are responsible for the diagnosis and treatment of various psychological problems.

Biological models of behavior have become increasingly prominent in psychological theory, particularly with the development of various tools—such as the positron emission tomography (PET) scan—for mapping the brain. The field of neuropsychology, which studies the brain and the connected nervous system, has been an outgrowth of this contemporary focus on biological explanations of human thought and behavior. Cognitive models, derived from the Gestalt school of psychology, focus on the various thinking processes which mediate between stimuli and responses.

Educational psychology, derived from the 18th and 19th cent. educational reforms of Friedrich W. Froebel, Johann Pestalozzi, and their follower Johann Herbart, was later expanded by G. Stanley Hall and by E. L. Thorndike. It is concerned with the development of improved methods of teaching and learning.

Social psychology, developed by British psychologists William McDougall and Havelock Ellis, studies the effects of various social environments on the individual. Some other branches of the field include developmental psychology, which studies the changes in thought and behavior through the course of life; experimental psychology, which is the laboratory research involved in the understanding of the mind; and personality psychology, which deals specifically with individual personality and the processes by which it is formed.

In recent years a number of new fields of psychology have emerged. Industrial/organizational psychology, emerging from social psychology, focuses on the workplace and considers such topics as job satisfaction, leadership, and productivity. Health psychology examines how psychological factors contribute to pathology, and demonstrates how psychology can contribute to recovery and illness prevention for such somatic disorders as heart disease, cancer, and diabetes. In environmental psychology, research focuses on how individuals react to their physical environments, and suggests improvements which may be beneficial to psychological health. Other new areas of psychology include counseling psychology, school psychology, forensic psychology, and community psychology.


See R. Fancher, Pioneers in Psychology (1979); D. Robinson, An Intellectual History of Modern Psychology (1986); E. Hilgard, Psychology in America (1987); M. Ash and W. Woodward, Psychology in 20th Century Thought and Society (1989); R. B. Evans, V. S. Sexton, and T. C. Cadwallader, ed., The American Psychological Association (1992).

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A psychologist is a social scientist who studies behavior and mental processes, generally in a research or clinical setting.


As psychology has grown and changed throughout history, it has been defined in numerous ways. As early as 400 B.C., the ancient Greeks philosophized about the relationship of personality characteristics to physiological traits. Since then, philosophers have proposed theories to explain human behavior. In the late nineteenth century, the emergence of scientific method gave the study of psychology a new focus. In 1879, the first psychological laboratory was opened in Leipzig, Germany by Wilhelm Wundt, and soon afterwards the first experimental studies of memory were published. Wundt was instrumental in establishing psychology as the study of conscious experience, which he viewed as made up of elemental sensations. In addition to the type of psychology practiced by Wundtwhich became known as structuralismother early schools of psychology were functionalism, which led to the development of behaviorism, and Gestalt psychology. The American Psychological Association was founded in 1892 with the goals of encouraging research, enhancing professional competence, and disseminating knowledge about the field.

With the ascendance of the Viennese neurologist Sigmund Freud and his method of psychoanalysis early in the twentieth century, emphasis shifted from conscious experience to unconscious processes investigated by means of free association and other techniques. According to Freud, behavior and mental processes were the result of mostly unconscious struggles within each person between the drive to satisfy basic instincts, such as sex or aggression, and the limits imposed by society. At the same time that Freud's views were gaining popularity in Europe, an American psychology professor, John B. Watson, was pioneering the behavioral approach, which focuses on observing and measuring external behaviors rather than the internal workings of the mind. B. F. Skinner, who spent decades studying the effects of reward and punishment on behavior, helped maintain the predominance of behaviorism in the United States through the 1950s and 1960s. Since the 1970s, many psychologists have been influenced by the cognitive approach, which is concerned with the relationship of mental processes to behavior. Cognitive psychology focuses on how people take in, perceive, and store information, and how they process and act on that information.

Additional psychological perspectives include the neurobiological approach, focusing on relating behavior to internal processes within the brain and nervous system, and the phenomenological approach, which is most concerned with the individual's subjective experience of the world rather than the application of psychological theory to behavior. While all these approaches differ in their explanations of individual behavior, each contributes an important perspective to the overall psychological understanding of the total human being. Most psychologists apply the principles of various approaches in studying and understanding human nature.

Along with several approaches to psychology there are also numerous, overlapping subfields in which these approaches may be applied. Most subfields can be categorized under one of two major areas of psychology referred to as basic and applied psychology. Basic psychology encompasses the subfields concerned with the advancement of psychological theory and research. Experimental psychology employs laboratory experiments to study basic behavioral processes shared by different species, including sensation, perception, learning, memory, communication, and motivation. Physiological psychology is concerned with the ways in which biology shapes behavior and mental processes, and developmental psychology is concerned with behavioral development over the entire life span. Other subfields include social psychology, quantitative psychology, and the psychology of personality.

Applied psychology is the area of psychology concerned with applying psychological research and theory to problems posed by everyday life. It includes clinical psychology, the largest single field in psychology. Clinical psychologistsaccounting for 40% of all psychologistsare involved in psychotherapy and psychological testing. Clinical psychologists are trained in research and often work in university or research settings, studying carious aspects of psychology. Like clinical psychologists, counseling psychologists apply psychological principles to diagnose and treat individual emotional and behavioral problems. Other subfields of applied psychology include school psychology, which involves the evaluation and placement of students; educational psychology, which investigates the psychological aspects of the learning process; and industrial and organizational psychology, which study the relationship between people and their jobs. Community psychologists investigate environmental factors that contribute to mental and emotional disorders; health psychologists deal with the psychological aspects of physical illness, investigating the connections between the mind and a person's physical condition; and consumer psychologists study the preferences and buying habits of consumers as well as their reactions to certain advertising.

In response to society's changing needs, new fields of psychology are constantly emerging. One new type of specialization, called environmental psychology, focuses on the relationship between people and their physical surroundings. Its areas of inquiry include such issues as the effects of overcrowding and noise on urban dwellers and the effects of building design. Another relatively new specialty is forensic psychology, involving the application of psychology to law enforcement and the judicial system. Forensic psychologists may help create personality profiles of criminals, formulate principles for jury selection, or study the problems involved in eyewitness testimony. Yet another emerging area is program evaluation, whose practitioners evaluate the effectiveness and cost efficiency of the programs.

Depending on the nature of their work, psychologists may practice in a variety of settings, including colleges and universities, hospitals and community mental health centers, schools, and businesses. A growing number of psychologists work in private practice and may also specialize in multiple subfields. Most psychologists earn a Ph.D. degree in the field, which requires completion of a four-to six-year post-bachelors' degree program offered by a university psychology department. The course of study includes a broad overview of the field, as well as specialization in a particular subfield, and completion of a dissertation and an internship (usually needed only for applied psychology, such as clinical, counseling, and school psychology). Students who intend to practice only applied psychology rather than conduct research have the option of obtaining a Psy.D. degree, which differs in the limited emphasis that is put on research and a dissertation that does not have to be based on an empirical research study.

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Psychology is the scientific study of human and animal behavior, which includes both observable actions (such as eating and speaking) and mental activities (such as remembering and imagining). Psychology tries to understand why a person or animal behaves a certain way and then seeks to predict how that person or animal will behave in the future. For many years, psychology was a branch of philosophy (the study and exploration of basic truths governing the universe, nature, life, and morals [a sense of right and wrong]). In the nineteenth century, scientific findings established it as a separate field of scientific study.

A brief history

In 1879, German physiologist Wilhelm Wundt (18321920) established the first formal laboratory of psychology at the University of Leipzig in Germany. Wundt's work separated thought into simpler processes such as perception, sensation, emotion, and association. His approach looked at the structure of thought and came to be known as structuralism.

In 1890, American philosopher William James (18421910) published his Principles of Psychology. In contrast to structuralists, James thought consciousness (awareness) flowed continuously and could not be separated into simpler elements. James argued that studying the structure of the mind was not as important as understanding how it functions in helping us adapt to our surroundings. This approach became known as functionalism.

In the early 1900s, Austrian neurologist Sigmund Freud (18561939) began formulating psychoanalysis, which is both a theory of personality and a method of treating people with psychological difficulties. Freud's most influential contribution to psychology was his concept of the unconscious. He believed a person's behavior is largely determined by thoughts, wishes, and memories of which they are unaware. Painful childhood memories are pushed out of consciousness and become part of the un conscious. From here they can greatly influence behavior. As a method of treatment, psychoanalysis strives to bring these memories to awareness, freeing an individual from their often-negative influence.

In 1913, American psychologist John B. Watson (18781958) argued that mental processes could not be reliably located or measured. He believed that only observable, measurable behavior should be the focus of psychology. His approach, known as behaviorism, held that all behavior could be explained as a response to stimuli in the environment. Behaviorists tend to focus on the environment and how it shapes behavior.

Words to Know

Behaviorism: School of psychology focusing on the environment and how it shapes behavior.

Cognitive psychology: School of psychology that focuses on how people perceive, store, and interpret information through such thought processes as memory, language, and problem solving.

Functionalism: School of psychology that focuses on the functions or adaptive purposes of behavior.

Gestalt psychology: School of psychology that focuses on perception and how the mind actively organizes sensations.

Humanistic psychology: School of psychology emphasizing individuals' uniqueness and their capacity for growth.

Neuropsychology: Study of the brain and nervous system and their role in behavior and mental processes.

Psychoanalysis: Theory of personality and method of psychotherapy founded by Sigmund Freud.

At about the same time behaviorism arose, German psychologists Max Wertheimer (18801943), Kurt Koffka (18861941), and Wolfgang Köhler (18871967) founded Gestalt psychology (German for "form" or "configuration"). Gestalt psychologists argued that perception and thought cannot be broken into smaller pieces without losing their wholeness or essence. They argued that people actively organize information and that the wholeness and pattern of things dominates the way people perceive the world.

In the 1960s, American psychologists Abraham Maslow (19081970) and Carl Rogers (19021987) helped develop humanistic psychology. They felt that past psychological approaches had focused more on human weakness and mental illness. These previous approaches neglected mental strength and the potential for self-fulfillment. Maslow and Rogers believed that everyone has a basic need to achieve one's unique human potential.

Contemporary psychology

Much contemporary research has taken place in cognitive psychology. This school of psychology focuses on how people perceive, store, and interpret information, studying processes like memory, language, and problem solving. Unlike behaviorists, cognitive psychologists believe it is necessary to look at internal mental processes in order to understand behavior.

Advances in the knowledge of brain and nerve cell chemistry in the late twentieth century have influenced psychology tremendously. New technologies, which have produced visual images of the human brain at work, have allowed psychologists to study exactly where specific types of mental processes occur. This emerging field has been labeled neuropsychology or neuroscience.

[See also Cognition; Psychiatry ]

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Originally the name given to the branch of philosophy dealing with the soul (from the Greek psyche, or soul), then to the science of the mind, and now generally understood to be the science of behavior, both human and animal, and of human thought processes. Early psychical research, in contrast, concerned itself with the demonstration and investigation of paranormal faculties and the concept of the soul, with the question of survival after bodily death as a legitimate inference.

According to the criterion of Charles Richet, everything that the human intelligence can do, even when it is most profound and penetrating, is psychological. Everything of which such intelligence is incapable belongs to metapsychics.

The crux of the matter is that the greatest difficulty is experienced in drawing the line between what the human intelligence can and cannot do, because many paranormal faculties appear to originate in the subconscious mind and manifest along the same channels as the phenomena of abnormal psychology. Their difference from abnormal phenomena seems to be primarily their social functionality.

Abnormal Psychology and the Paranormal

Some would contend that an abnormal bodily condition may facilitate the function of a paranormal faculty without being the reason and cause of it. Hereward Carrington, in The Story of Psychic Science (1930), relates the story of a female acquaintance who fell into Lake Minnetonka, sank three times, and was rescued unconscious. A severe illness complicated with pneumonia followed her misadventure. During her convalescence she became clairvoyant and could tell what letters were in the mailbox in the morning and often their approximate contents. When she was completely restored her clairvoyant faculty disappeared.

Neither pneumonia nor near-drowning can be supposed the cause of such clairvoyance. Similarly it is reasonable to infer that in the clairvoyance of hysteric subjects, the abnormal bodily condition is simply a coincidental phenomenon but not the cause and explanation of the clairvoyance. An abnormal condition may open up a channel of function for paranormal faculties. If the abnormal condition becomes permanent, mediumship may develop in organisms that constitutionally were not adapted for paranormal manifestations.

The study of abnormal psychology may also have relevance to the emotional and temperamental problems of some mediums, particularly those who are disposed to fraudulent tricks, even if gifted with some genuine psychic faculties.

Parapsychology adopted much from modern behavioral studies and does not assume any particular psychological structure, as did psychical research. Its name implies that it is a branch of psychology that specializes in the study of paranormal behavior. Parapsychologists seek to use appropriate psychological methodologies and integrate their findings into the larger body of psychological knowledge.


Beloff, John. The Existence of Mind. London: MacGibbon, 1962. Reprint, New York: Citadel, 1965.

Brown, William. Science and Personality. New Haven, Conn.: Yale University Press, 1929. Reprint, College Park, Md.: McGrath, 1972.

Burt, Cyril. Psychology and Psychical Research. London: Society for Psychical Research, 1968.

Ehrenwald, Jan. Telepathy and Medical Psychology. New York:W. W. Norton, 1948.

Eysenck, H. J. Sense and Nonsense in Psychology. London: Penguin, 1957.

Hudson, Thomas J. The Law of Psychic Phenomena: A Working Hypothesis for the Systematic Study of the Vast Potential of Man's Mind. New York: G. P. Putnam's Sons, 1894. Reprint, Chicago: Hudson-Cohan, 1970. Reprint, New York: Weiser, 1972.

LeShan, Lawrence. The Medium, the Mystic, and the Physicist: Towards a General Theory of the Paranormal. New York: Viking Press; London: Turnstone Books, 1974.

McCreery, Charles. Science, Philosophy, and ESP. London: Faber & Faber, 1967. Reprint, Hamden, Conn.: Archon Books,1968.

Mitchell, T. W. Medical Psychology and Psychical Research. London: Methuen, 1922.

Myers, F. W. H. Human Personality and Its Survival of Bodily Death. 2 vols. London: Longmans, Green, 1903. Reprint, New York: Longmans, Green, 1954. Abr. ed. New Hyde Park, N.Y.: University Books, 1961.

Osty, Eugene. Supernormal Faculties in Man. London: Methuen, 1923.

Rhine, J. B., and Robert Brier. Parapsychology Today. New York: Citadel, 1968.

Rosenthal, Robert. Experimenter Effects in Behavioral Research. New York: Appleton-Century-Crofts, 1966.

Schmeidler, Gertrude R. ESP in Relation to Rorschach Test Evaluation. New York: Parapsychology Foundation, 1960.

Wolman, Benjamin B., ed. Handbook of Parapsychology. New York: Van Nostrand Reinhold, 1977. Reprint, Jefferson, N.C.: McFarland, 1986.

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Psychology is the science of the mind. An appreciation of what is happening of the mind of a criminal and why he or she acts as she does can be an important part of any investigation. A forensic psychologist (or psychiatrist, if they are medically qualified) can carry out a number of functions, such as assessing the mental stability of a suspect, building a psychological profile of the perpetrator and victim, and trying to understand the motivation for a crime.

Psychological tests can be useful in learning more about a suspect and their behavior. Standardized personality screening tests, of the kind that are sometimes also used in recruitment, can reveal the suspect's basic personality type. The tests are lists of questions to be checked which elicit responses about behavior, emotion, social skills, and beliefs. One common personality test includes the Minnesota Multiphasic Personality Inventory (MMPI), which can reveal if someone is suffering from a mental disorder such as anti-social personality disorder.

The psychologist may also use more subjective tests known as projective tests, which reveal more about inner conflict, fantasies, and thought processes. In the widely used Rorschach inkblot test, the suspect is shown a series of abstract inkblots and asked to describe what he sees. Another approach is to ask the subject to draw something like a house or a frightening scene. This can be very revealing of the suspect's fantasies and may be in complete contradiction to what they actually say to the psychologist.

The third kind of psychological test that may be administered is a cognitive test that measures the suspect's intelligence, mental competency, thought processes, and ability to understand his or her behavior. A common example is the Wechsler Adult Intelligence Scale. Less structured interviews will also be carried out, where the suspect may be encouraged to talk about their family, childhood, relationships, and problems. The psychologist will lead up to a discussion of the events that brought the suspect in for interrogation and try to find out how they feel about what happened. Of course, many suspects lie, but a skilled psychologist will be able to sort out the truth from the fiction by analysis of the subject's body language.

see also Profiling, screening; Psychiatry.

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psychology The word ‘psychology’, from the Greek psyche, meaning mind or soul, describes an academic and clinical subject concerned with reason and emotion, conscious and unconscious mental processes. It has become an umbrella term for such a wide variety of ‘disciplines’, paradigms, and cults that it is not clearly definable. The caring professions, especially for mental problems, are important activities under this rubric. Perhaps most intellectually respectable is experimental psychology, concerned especially with learning, memory, perception, attention, and emotions — with explicit links to physiological processes of the brain and body. These are of practical importance for understanding the consequences of brain damage and mental illnesses such as schizophrenia.

Although the scientific aspects of psychology are increasingly seen as falling within the broad remit of neuroscience, the conceptual association of physical brain to mental mind raises philosophical questions which remain controversial after thousands of years of debate. Current accounts of the mind, created by brain processes, generally refer to an analogy to the hardware–software distinction for computers. Computers, though physical, are ‘cognitive’ in that they carry symbols and meaning. But, so far as we know, computers are not conscious: the explanation of consciousness remains a great challenge for both psychology and brain sciene.

Richard L. Gregory

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The field of psychology plays an integral role in public health, providing treatment and education in the areas of substance abuse, addiction, and other health-related behaviors. Individuals suffering from addiction and other psychological disorders have a major impact on a community, and on the nation, causing financial loss, accidents, decreased business productivity, and numerous social and psychological effects. Therapeutic techniques for these individuals focus on development of coping skills, ego strength, improved self-esteem, and other traits needed to lead a healthy life. Assessment, community profiling, and creating and conducting prevention and treatment programs for the public also fall within the realm of psychology. In addition, psychologists conduct research in public health problems and serve as consultants in the development of solutions to these problems.

Sandra K. Clarke

(see also: Behavior, Health-Related; Behavioral Change; Community Psychology; Psychology, Health; Substance Abuse, Definition of )

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psychology Study of mental activity and behaviour. It includes the study of perception, thought, problem solving, personality, emotion, mental disorder, and the adaptation of the individual to society. It overlaps with many other disciplines, including physiology, philosophy, artificial intelligence, and social anthropology. Central areas of psychology include neuropsychology, which relates experience and behaviour to brain functioning; cognitive psychology, which studies thought processes; social psychology, which studies behaviour in its social context; and developmental psychology, which studies the cognitive and emotional development of children. Applied psychology aims to use the discipline's insights into human behaviour in practical fields, such as education and industry. See also behaviourism; ethology; learning; memory

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psy·chol·o·gy / sīˈkäləjē/ • n. the scientific study of the human mind and its functions, esp. those affecting behavior in a given context. ∎  [in sing.] the mental characteristics or attitude of a person or group: the psychology of Americans in the 1920s. ∎  [in sing.] the mental and emotional factors governing a situation or activity: the psychology of interpersonal relationships.

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psychologist (sy-kol-ŏ-jist) n. a person who is engaged in the scientific study of the mind. clinical p. a psychologist trained in aspects of the assessment and treatment of the ill and handicapped. He or she usually works in a hospital. educational p. a psychologist trained in aspects of the cognitive and emotional development of children. He or she usually works in close association with schools.

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psychology (sy-kol-ŏji) n. the science concerned with the study of behaviour and its related mental processes. The different schools of psychology include behaviourism, cognitive psychology, psychoanalysis, and gestaltism.
psychological (sy-kŏ-loj-ikăl) adj.

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