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Richter, Curt P.


(b. Denver, Colorado, 20 February 1894; d. Baltimore, Maryland, 22 December 1988) psychobiology, biological clocks, homeostasis.

Richter’s research career began at Harvard University, where he was an undergraduate assistant to Robert

M. Yerkes before graduating in 1917. Yerkes, a comparative psychologist, advised him to go to graduate school at the Johns Hopkins University and study under John B. Watson, who was becoming known for his strict behaviorist views.

Early Life and Career Richter’s parents were newly arrived from the Saxony region of Germany when Richter was born. He grew up Denver, Colorado, where they ran a machine factory. Richter’s early experience in his parents’ factory was an important formative experience for him. As Richter described in an autobiographical essay, “It’s a Long Way to Tipperary,” (1985), he learned about tools and machines during the long hours that he spent in the factory. He described the context as “play” and himself as being fascinated with all kinds of gadgets; he began to experiment (e.g., with magnets) at a young age. As Richter recalled his childhood, “I spent a lot of time working on locks and clocks—taking them apart and putting them back together again” (Richter, 1985, p. 359).

Meanwhile, Richter received his formal education in the public schools of Denver, graduating from high school in 1912. Then, following what he remembered from childhood as his father’s wish, he enrolled at an engineering school in Germany. For the greater part of the period from 1912 to 1915, he studied at the Technische Hochschulen in Dresden. Reflecting on the experience at the engineering school, Richter said, “looking back on my work at the Hochschule, I have come to realize how much I learned that has helped me in the running of my Laboratory of Psychobiological Biology” (Richter, 1985, p. 365). Next attending Harvard University in Cambridge, Massachusetts, he excelled in no particular subject until he took a course in genetics, followed by one in the philosophy of nature with E. B. Holt, a student of William James. The latter course then “stimulated me to sign up for a short experimental course on insect behavior, given by Professor Robert Yerkes” (p. 369). His research career began at Harvard, where in his senior year he was a student-assistant to Yerkes. Before Richter graduated in 1917, Yerkes, a comparative psychologist, advised him to go to graduate school at Johns Hopkins University and study under John B. Watson, who was becoming known for his strict behaviorist views. In his autobiography, reflecting on his time as an undergraduate at Harvard, Richter recalled that

Yerkes recommended that I read a book, Animal Behavior, by John B. Watson. After having read only snatches here and there, I became convinced that I should try to work with him.… I must point out here that at that time, and for a long time later, I had no idea about what Watson meant by “behaviorism.” For me “behaviorism” simply meant “behavioral.” (Richter, 1985, p. 369)

After serving in the army in 1917–1918, Richter did as Yerkes had recommended, arriving at Johns Hopkins’s Phipps Clinic in Baltimore, Maryland, to begin graduate studies with Watson. Richter recalled Watson uttering these words: “I want you to know that I am only interested in getting a good piece of research. You do not have to take any course or attend any lectures. You are strictly on your own” (Richter, 1985, p. 371). After Watson’s departure from Johns Hopkins, Adolf Meyer, who has been called the father of psychobiology, became the main supporter of Curt Richter’s research. Meyer also understood psychobiology as a discipline “that takes life as it is without splitting it into something mental and something physical” and that considers the “organismal function and behavior” (Meyer, 1935, p. 94). Richter’s dissertation, accepted in 1921, was titled “The Behavior of the Rat: A Study of General and Specific Activities.” An attempt to study spontaneous, self-generated behaviors (see below), the dissertation planted the seed for a career in research.

Richter’s subsequent empirical research falls into four overlapping categories: (1) the regulation of spontaneous behaviors; (2) homeostatic and nutrition selection; (3) the effects of domestication; and (4) neurological discovery and invention. These were informed by a strongly biological orientation, a preference for hands-on experiments, and a passion for measurement.

Biological Clocks During the 1920s Richter began his research career by studying cyclic behavior and what many called “spontaneous behaviors.” He understood biological clocks as fundamental to the organization of behavior and physiological adaptation. But a full development of the role of clocks in regulating behavior and physiology, particularly in mammals, would await decades. Richter set about demonstrating the role of clocks and their operation under pathological conditions.

For Richter, cyclic behaviors were internally generated and innate. Two issues stood out for him: regularity and uniformity. Clocks keep time and provide order and coherence, which is required by the outer world to which we are trying to adapt. With the advent of Darwinism, fitness and long-term survival became linked by biologists to cyclical events. In Richter’s view, the clocks themselves were fixed. They, of course, reflected the events of nature, the daily and seasonal rhythms.

In his experiments, Richter noted alternating patterns of activity and inactivity. He noted that the patterns of active behavior varied with different animals and with age. In young rats, the rate of alternating between activity and inactivity is much greater than in older rats. Richter noted that this pattern of behavioral alternation was present in the newborn rat and presumably was an innate, hardwired behavioral pattern that was expressed in a diverse range of animals.

During the 1920s, Richter was also beginning to determine that internal oscillators played an important role in the organization of diverse forms of anticipatory behavioral adaptation. One key feature that facilitates activity-inactivity in diverse animals is the light-dark cycle. Circadian clocks orient and synchronize an animal’s adaptive behavioral and physiological responses to periodic changes in the environment. The circadian clock is a fundamental timing device present in a wide variety of species.

Richter discovered that an ablation “somewhere in the hypothalamus” would disrupt circadian rhythmicity. Subsequently, it would become known that Richter indeed was close to localizing the region that is essential for circadian rhythmicity. He had noted that damage within the hypothalamus disrupted circadian rhythmicity. Later it would be discovered that the essential region is the suprachiasmatic region (SCN) of the hypothalamus.

During the 1960s, Richter also suggested two types of sleep regulatory mechanisms, one linked to homeostatic requirements for sleep and the other to circadian rhythmic activity. This distinction has credibility among chronobiologists. He suggested that sleep activity was tied to the reticular formation, perhaps beholden to homeostatic needs.

Richter surmised that there were multiple clocks. A study of individual animals showed some variation in the clocks under normal conditions that was further exaggerated under pathological conditions. Richter documented a long list of clinical syndromes that were periodic and linked to bodily pathology. Some of the examples that he noted were acciosis, periodic bleeding, Hodgkin’s disease, Parkinsonian pariesis, peptic ulcer, manic-depressive illness, sleep disturbances, and catatonic schizophrenia.

Behavioral Homeostasis Building on the work of Claude Bernard and Walter Cannon, Richter added an important element: behavioral regulation of the internal milieu was a fundamental scientific question for Curt Richter. Richter was not alone in his interest, but he certainly was a major force in providing interesting and informative contexts in which to consider the biological adaptation required for bodily health.

Richter’s research in this area during the 1930s– 1950s centered around the question of adaptive versus nonadaptive nutritional choice behaviors. Richter selected an important way into the study of ingestive behavior: the behavioral regulation of and taste psychophysics of sodium. Richter’s insight was to add sources of sodium to the diet and then study the ingestion of sodium by the “appetite method,” as he liked to call it. Richter noted a range of ingestive patterns that was heavily biased toward sodium solutes when animals were hungry for sodium, something many other investigators also observed after him.

When Richter and his colleagues turned to the study of calcium homeostasis during the 1930s–1940s, he approached the problem in the same manner as he did that of sodium. First, he demonstrated a calcium appetite, and then he suggested that the behavior was organized by innate behavioral mechanisms, an innate capacity to detect calcium salts triggered by decreased levels of calcium.

Richter and his colleagues demonstrated that a number of substances (e.g., sodium chloride and calcium lac-tate) are further ingested during pregnancy and lactation, when there is further need for them. They also noted that water intake was particularly elevated during lactation.

Nutrient search and identification are basic features of biological hardware. Richter’s studies of laboratory rats in the 1940s and 1950s revealed several instances of specialized systems for water, sodium, calcium, and perhaps phosphate ingestion and some aspects of energy balance. Richter understood the regulation of the internal milieu in the context of whole-body regulatory activity.

Nutrient search and identification are basic features of biological hardware. Richter believed that all ingestive behaviors, except for learned aversions for foods (see below), reflect innate appetites. He asserted that rats (his animal of study for the specific hungers), in response to bodily needs, have special appetites for a wide range of substances, including sodium, carbohydrates, protein, calcium, and phosphorus in addition to diverse vitamins. Richter remained a nativist regarding all the specific hungers, but he was mistaken.

How many innate-instinctive specific appetites are there? Certainly sodium and perhaps calcium. Water seems a likely candidate, and protein remains a possibility. Avoidance of diets that render the animal ill, coupled with a tendency to be cautious of new nutritional options, seem to be operative in food choice, particularly for the omnivorous rat. Ecological adaptations are an essential part of discerning the range of strategies available for an animal to solve its nutritional requirements. Richter’s work on nutritional selection was done largely for the rat, an omnivore with several noted specific appetites, along with several more general behavioral strategies, that serve it in the regulation of the internal milieu.

Adaptation and Domestication Richter’s roving experimental eye brought him to a phenomenon that would later have a profound effect on American psychology and the understanding of learning, something called “taste aversion learning.” Richter, whose insight was rooted in biological considerations, simply understood that the normal reluctance to ingest unfamiliar foods made the wild rat difficult to trap and that gustation was a primary sensory modality and part of the alimentary canal that included gastrointestinal functions. Taste aversion learning would play an important role in the coming battles in psychology with regard to the biological basis of learning and would alter the conceptual and experimental landscape of psychology.

Richter, the self-dubbed “reluctant rat-catcher,” caught many rats in the wilds of Baltimore over a ten-year period. He enjoyed this avenue of research. It consisted of scanning a rough environment for a wild animal and testing modern substances that might be linked to a genetic taste function—one that might underlie the self-selection of diets and the avoidance of possibly harmful substances—in physiological and gustatory studies. This special behavioral adaptation serves the animal well in tagging food sources and, most importantly, in linking specific food ingestion with visceral distress in animals in which taste and olfaction are essentially linked to food regulation.

Richter was close to suggesting something like a form of taste aversion with his emphasis on “bait shyness,” food avoidance, and visceral distress from poisoning. For example, as indicated above, in one set of experiments he determined the different concentrations of the toxin that would result in food avoidance. Noticing a relationship between the concentrations of the toxin and food avoidance, he reported in 1946 that, when exposed to various concentrations of the toxins, rats stopped eating the food after it made them ill.

Richter investigated the effects domestication on behavior and physiology and made important contributions to this area of inquiry (e.g., size diverse end organ systems in wild and domesticated animals). The effects of domestication on a variety of behavioral and end organ systems were fairly well-known at the time of Richter’s investigations in the 1940s and 1950s. But he added a new and systematic dimension to his research by the range of end organ systems that he investigated. For example, Richter and his colleagues demonstrated changes in adrenal, thyroid, and pituitary glands; gonads; and regions of the brain.

Richter always began his investigations with an adaptationist conception of evolution on the effects of domestication and the use and disuse of morphological and behavioral expression. But he also suggested ways in which devolution and the loss of adaptation occurs.

Neurological Study Richter noted several facts that implied individual differences and cyclic daily patterns in the grasp reflex. There were two themes in Richter’s research. Underlying his research on the grasp reflex was the importance of clinging on to the mother during the neonatal period. As Richter noted, the grasp reflex was an important aid for keeping infants afloat. He also suggested that the grasp reflex appeared to be less prominent in the human than in the monkey. The grasp reflex method he used with the monkey was different from that used with the human neonate, however, and so his comparison was misleading. Nonetheless, Richter built on the common evolutionary theme that the grasping reflex was stronger in the monkey than in the human. He also noted variations in the grasping response from day to day.

In 1919 “A Graphic Application of the Principle of the Equilateral Triangle …,” the very first paper of which Richter was an author, reported on a formal technique suggesting that an equilateral triangle could be used to predict the electrical patterns of the heart. Having developed a small portable dermometer (i.e., galvanometer), Richter and his colleagues subsequently measured skin resistance and, with some continued prodding and instruction, he extended its use both to show the simplicity of this technique and to determine peripheral damage.

Further studies by Richter and his colleagues helped to ascertain the mechanisms of sweating and skin resistance. The legacy of the laboratory Richter inherited, namely Watson's, was the use of the grasping reflex. Richter would use this reflex to investigate the neurology and the pharmacology that made this reflex possible. Unlike Watson, he remained rooted in a neurological tradition in which evolution permeated the conception of the brain.

Research Style Richter found ingenious ways to study phenomena. His approach was hands-on, dirty, and devoid of pristine logical analysis. He was a scientific scavenger-entrepreneur. The experiment dominated his conception of what it meant to be a psychobiologist. He embodied what can be termed a laboratory state of mind.

A laboratory state of mind is one in which measurement predominates. In interviews with Anne Roe in 1952, for example, Richter tellingly said when asked about his thinking process: “I would say that I think really very little in terms of words. I think largely in terms of moving my hands. I find that I am always about 10 steps behind in my verbalizations.” A little later he is quoted as saying: “I have a passion, I suppose, for measuring things” (Roe, interview notes, 1952, Archives, American Philosophical Society, Philadelphia).

Richter considered himself lucky to have worked mostly in an age before “big science,” which would come to undermine what he romanticized as “free science.” In the 1950s, the era of big grant writing was at hand. Now, Richter lamented, to get a grant one had to know in advance what one was going to find out. Exploration and play, he feared, would be undermined and scientific creativity would be compromised.

Richter prided himself on his surgical abilities. Eliot Vallenstein, a professor of psychology at the University of Michigan, recalled a time when Richter was applying for a grant. He pleaded with the review committee not to let his age (he was then in his late seventies) affect its judgment, that he needed the money for his assistant who had been with him for many years. Moreover, he said, “my eyes are clear, my hands are steady, and I have performed 784 operations this year” (E. Vallenstein, personal communication, July 2002; Schulkin, 2005, p. 128).

Although he was never part of its mainstream, within the field of psychology Richter is typically associated with the concept of drive. One noted historian of psychology in America describes Richter as “a persistent and ingenious experimenter” (Hilgard, 1987).

The biological basis of behavior permeated Richter’s work. His lack of interest in the theoretical and intellectual debates of his day is exemplified in the stance he took during an important conference that he attended in 1956, where he remained apart from the debate, instead keeping his focus on his data and experimental results.

Fearless and Free Richter was a fearless artisan-scientist. An artisan laboratory sensibility ran through his veins, and it is seen in the simplicity of his techniques, the beauty of his laboratory, the devotion to his scientific inventions. His contributions to science in the new field of psychobiology had tremendous range. The one “com-pleat psychobiologist” would be allowed a free rein. Consequently, he was able to eschew committees and the responsibilities that went with them.

Drawing on material he had presented to a committee at the National Research Council, Richter published in Science“Free Research versus Design Research” (1953), which drew heavily on his philosophical side. As the article illustrates, Richter was not of the era of experimental design. In the article he rightly recognized the importance of statistical design but asserted that it “should not substitute for ideas” (p. 92). Most of Richter’s contemporaries, whatever their theoretical orientation, did not absorb statistical methods. An important contribution from behavioral psychology would be the logic of experimental design. Experimental design would come to figure in all aspects of the behavioral sciences, along with the use of statistical analysis.

When Richter published the Science article, he was only a few years from emeritus status. He would continue doing research for another twenty-five years, but he was already “old school.” Richter was fortunate to have received multisource funding. For example, he obtained support from the Rockefeller Foundation (1923–1940, via Adolf Meyer), the National Institutes of Health (1952–1965), the National Science Foundation (1956–1977), the National Research Council (1937–1945), the National Council on Alcoholism (1959–1960), and the Commonwealth Fund (1964–1977).

Richter sought to escape the endless debates taking place within academic psychology. He remained a steadfast experimentalist, while perhaps exaggerating innate behavioral solutions. When this failed, there was always the practical side of knowledge—the clinic, the patient. In these contexts, the engineer could come forward, extending and simplifying devices to measure physiological events that could be used to discern disease and dysfunction. Even at the very end of his life, he published papers on growth hormone (“Growth Hormone 3-6hr Pulsatile Secretion and Feeding Time Have Similar Periods in Rats,” 1980) and cortisol secretion in rats, guinea pigs, and monkeys (“Possible Origin of a 90-Min. Cortisol Secretion Cycle in Rats, Guinea Pigs, and Monkeys,” 1983) and remained productive, active, and engaged in his scientific pursuits.

One does not get the sense that Richter was changing his mind about core ideas. What would have made him think that perhaps a range of appetitive behaviors required diverse forms of learning? A set of core ideas or metaphors underlies the behavior of scientists, including Richter. His core ideas centered around behavioral adaptation, regulation of the internal milieu, cyclic behavior, and instinctive behavior. Richter set out to demonstrate behavioral competence, physiological signals that orchestrate adaptation to diverse perturbations to the internal milieu.

Richter very much enjoyed both the prestige of and participation in academic societies (e.g., the American Philosophical Society and the National Academy of Sciences). He maintained an active sense of inquiry for over sixty years, all at the Department of Psychiatry at Johns Hopkins University.

Richter was married twice and had three children. He died in Baltimore, Maryland, on 22 December 1988.



With E. P. Carter and C. H. Greene. “A Graphic Application of the Principle of the Equilateral Triangle for Determining the Direction of the Electrical Axis of the Heart in the Human Electrocardiogram.” Johns Hopkins Hospital Bulletin 30 (1919): 162–167.

“A Behavioristic Study of the Activity of the Rat.” Comparative Psychology Monographs 1 (1922): 1–55.

“Nervous Control of the Electrical Resistance of the Skin.” Johns Hopkins Hospital Bulletin 45 (1929): 56–74.

“The Grasping Reflex in the New-Born Monkey.” Archives of Neurology and Psychiatry 26 (1931): 784–790.

With Arthur S. Paterson. “On the Pharmacology of the Grasp Reflex.” Brain 55 (1932): 391–396.

“Total Self Regulatory Functions in Animals and Human Beings.” Harvey Lectures Series 38 (1942–1943): 63–103.

“Incidence of Rat Bites and Rat Bite Fever in Baltimore.” Journal of the American Medical Association 128 (1945): 324–326.

“Biological Factors Involved in Poisoning Rats with Alpha-naphthyl Thiourea (ANTU).” Proceedings of the Society of Experimental Biology and Medicine 63 (1946): 364–372.

“Instructions for Using the Cutaneous Resistance Recorder, or ‘Dermometer,’ on Peripheral Nerve Injuries, Sympathectomies, and Paravertebral Blocks.” Journal of Neurosurgery 3 (1946): 181–191.

“Physiology and Endocrinology of the Toxic Thioureas.” Recent Progress in Hormone Research 11 (1948): 255–276.

“Domestication of the Norway Rat and Its Implication for the Study of Genetics in Man.” American Journal of Human Genetics 4 (1952): 273–285.

“Free Research versus Design Research.” Science 118 (1953): 91–93.

“Salt Appetite of Mammals: Its Dependence on Instinct and Metabolism.” In L’instinct dans le comportement des animaux et de l’homme, edited by P. P. Grasse. Paris: Masson et Cie, 1956.

“Experiences of a Reluctant Rat-Catcher: The Common Norway Rat—Friend or Enemy?” Proceedings of the American Philosophical Society 112 (1968): 403–415.

Biological Clocks in Medicine and Psychiatry. 2nd ed. Springfield, IL: C.C. Thomas, 1979.

“Growth Hormone 3-6hr Pulsatile Secretion and Feeding Time Have Similar Periods in Rats.” American Journal of Physiology 239 (1980): E1–2.

“Possible Origin of a 90-Min. Cortisol Secretion Cycle in Rats, Guinea Pigs, and Monkeys.” American Journal of Physiology 244 (1983): R514–515.

“It’s a Long Way to Tipperary, the Land of My Genes.” In Leaders in the Study of Animal Behavior: Autobiographical Perspectives, edited by D. A. Dewsbury. Lewisburg, PA: Bucknell University Press, 1985.


Blass, Elliott M., ed. The Psychobiology of Curt Richter. Baltimore, MD: York Press, 1976.

Garcia, J., W. G. Hankins, and K. W. Rusiniak. “Behavioral Regulation of the Milieu Interne in Man and Rat.” Science 185 (1974): 824–831.

Hilgard, Ernest R. Psychology in America: A Historical Survey. San Diego, CA: Harcourt Brace Jovanovich, 1987.

Meyer, A. “Scope and Teaching of Psychobiology.” Journal of the American Medical Association 10 (1935): 93–98.

Roe, Anne. The Making of a Scientist. New York: Dodd, Mead, 1953.

Rozin, Paul. “The Compleat Psychobiologist.” In The Psychobiology of Curt Richter, edited by Elliott M. Blass. Baltimore, MD: York Press, 1976.

Schulkin, Jay. Curt Richter: A Life in the Laboratory. Baltimore, MD: Johns Hopkins University Press, 2005.

Stellar, Eliot. “Curt P. Richter.” American Philosophical Society Biographical Memoirs (1989): 293–297.

Jay Schulkin

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