MEMORY

autobiographical memory
charles p. thompson

development of
patricia j. bauer rebecca m. starr

graphics, diagrams, and videos
priti shah

implicit memory
henry l. roediger iii lisa geraci

mental models
gabriel a. radvansky
david e. copeland

metamemory
gregory schraw
john nietfeld

myths, mysteries, and realities
elizabeth j. marsh

structures and functions
peter e. morris

AUTOBIOGRAPHICAL MEMORY

In the early twenty-first century there is general agreement among memory researchers that memory consists of a number of distinctly different types of memory rather than one single memory. A brief overview of the major divisions in memory will help put autobiographical memory in context. Philosophers have long made a distinction between knowinghow (e.g., knowing how to ride a bicycle) and knowing what (e.g., knowing what a bicycle is). Modern research has verified the distinction between these two types of memory, and they are currently called procedural or implicit memory (knowing how) and declarative or explicit memory (knowing what). In 1972 Endel Tulving divided declarative memory into semantic and episodic memory. Semantic memory, because it contains general information such as facts, names, and important historical dates, could be described as a person's knowledge of the world. Episodic memory refers to a person's memory of events.

Autobiographical memory is a large and important subset of episodic memory containing those events that constitute the story of one's life. In the words of Katherine Nelson, autobiographical memory is "specific, personal, long-lasting, and (usually) of significance to the self-system. Phenomenally, it forms one's personal life history" (p. 8). If the first meeting with a loved one involves going to a movie, that event stands a good chance of becoming part of autobiographical memory. Other occasions on which movies are attended, however, will be remembered for a short time but probably will not become part of autobiographical memory. Instead, those events will contribute to generic memory. Generic memory contains memory for frequently occurring events such as brushing teeth or going to a movie. When asked about such events, it is unlikely that a specific instance of toothbrushing or going to a movie will be remembered.

The Organization of Autobiographical Memory

Autobiographical memory is organized as nested clusters of events that are all highly interconnected. Take the memory of a lawyer as a hypothetical example. Under the topic of school, that person would find events for elementary school, secondary school, college, and law school. Nested under each of those categories would be the events for each year (e.g., sophomore in college). Under the category of sophomore in college would be the events for each semester, which, in turn, would be grouped in categories such as academic events (e.g., classes), jobs, and friends. All these autobiographical events would be accessible in a number of ways. A particular event might involve a certain year in college, a particular job, and certain friends. That event could be accessed when thinking about school, friends, or jobs.

The topic of school is just one example of the many topics that have many subcategories. Other such topics include marriage, jobs, and military service. Just like the clusters of events nested under topics, the topics also are highly interconnected. The end result is a memory system that has the ability to retrieve the memory of a particular event from a large number of starting points. The most obvious example of the power of autobiographical memory to retrieve events is involuntary memory–memories that just pop into mind. In a 1998 article Dorthe Berntsen described her studies of involuntary memories, which showed that people average six to eight such memories every day.

Memory for Autobiographical Events

Remembering an autobiographical event usually involves both retrieving the content of the event (remembering what) and placing it in time (remembering when). Of course, memory for both fades over time. Autobiographical memory can be either reproductive or reconstructive. When it is reproductive, virtually all the details are retrieved from memory. When it is reconstructive, a few major points are retrieved from memory and the rest is constructed from generic memory. People are very good at reconstructing memory from generic events, and they are usually not aware that they are doing so. One of the consequences is that memory for old events is often wrong. Sometimes the error is minor and sometimes it is not.

Memory researchers have shown that memory for the content of the event gradually changes from being almost entirely reproductive to being, after about a year, almost entirely reconstructive. By contrast, memory for when an event occurred is almost always entirely reconstructive.

There are three additional distinctive characteristics of memory for autobiographical events. First, as time passes, the number of events that can be recalled drops off rapidly at first and then more slowly–a negatively decelerating curve. Second, older people show what David C. Rubin and his colleagues called a "reminiscence bump." Older people recall more events for the period when they were in their twenties than predicted by the negatively decelerating memory curve. Typically, many important life events (such as college graduation, marriage, and children) occur when people are in their twenties. Research has shown that the reminiscence bump can be attributed to these important life events. Third, almost all people show infantile amnesia. When people are asked to recall events from their childhood, they usually cannot recall events prior to age three. Not only are they unable to recall memories before age three, but the number of memories retrieved between ages three and six is also markedly below the number available after that period. Infantile amnesia is an intriguing puzzle because researchers have shown that children under age three can report details of isolated specific events and, most important, can remember them for up to two years. There is a growing consensus that the answer to the puzzle may lie in the development of autobiographical memory.

The Development of Autobiographical Memory

By the early twenty-first century there was considerable evidence that children learn how to talk about memories with others. They learn how to tell their life stories as a narrative. This is the social interaction view of autobiographical memory. This view proposes that infantile amnesia is overcome when children learn how to retain their memories in a recoverable form by turning them into narratives.

One strong source of support for the social interaction view has been the investigation of mother-child discussions of past events. These discussions can be classified as narrative or pragmatic. The narrative conversations focused on what happened when, where, and with whom. The pragmatic conversations used memory to retrieve specific information such as "Where did you put your book?" Children of mothers who used the narrative type of discussion remember more about the events than children of mothers who used the pragmatic type of discussion.

Autobiographical Memory as an Expert System: Implications for Learning

Experts learn new material in their field much faster than novices, and they retain that material much better as well. The reason for their outstanding performance in learning and memory is that they have a highly organized and detailed memory for their area of expertise. This allows them to relate new material to one or more pieces of information that they already know. Metaphorically speaking, they have many potential pegs on which they can hang new information. When they have to retrieve the new information, they can follow a well-beaten path to that information.

Autobiographical memory is also a highly organized and detailed memory. When it is possible to relate new information to life events, autobiographical memory functions in the same way as an expert system. The new information will be learned faster and remembered better than information that cannot be related to life events (or to another expert system).

Life Is Pleasant–and Autobiographical Memory Makes It Better

In studies of subjective well-being conducted around the world, people generally report that they are happy with their life. In the United States, this positive feeling is found in people with physical disabilities, people with mental illness, low-income people, minorities–in short, it is found for virtually all categories. Research on autobiographical memory shows two sources for this positive feeling of well-being. First, life events are generally pleasant with positive events occurring roughly twice as often as negative events. This is true for childhood memories, involuntary memories, and adult memories.

Second, the general level of pleasantness typically is enhanced when remembering life events. That occurs because the emotion attached to the events fades over time but the emotion for unpleasant events fades much faster than the emotion for pleasant events. Thus, the overall emotional tone becomes more pleasant for autobiographical memory. The mechanism responsible for this change appears to be the rehearsal (thinking about or talking about) of pleasant events.

For most people, autobiographical memory is a very positive and useful part of memory. It is equivalent to an expert system and therefore can be very helpful in learning new material. Most important, it holds the story of one's life. That story is typically very pleasant and, because negative emotions fade rapidly, becomes more pleasant as time passes. People's lives would be much reduced without their access to autobiographical memory.

See also: Memory, subentries on Development of, Myths, Mysteries, and Realities.

bibliography

Berntsen, Dorthe. 1998. "Voluntary and Involuntary Access to Autobiographical Memory." Memory 6:113–141.

Diener, Ed, and Diener, Carol. 1996. "Most People Are Happy." Psychological Science 7:181–185.

Fivush, Robyn; Haden, Catherine; and Reese, Elaine. 1995. "Remembering, Recounting, and Reminiscing: The Development of Autobiographical Memory in Social Context." In Constructing Our Past: An Overview of Autobiographical Memory, ed. David C. Rubin. New York: Cambridge University Press.

Hudson, Judith A. 1990. "The Emergence of Autobiographic Memory in Mother-Child Conversation." In Knowing and Remembering in Young Children, ed. Robyn Fivush and Judith A. Hudson. New York: Cambridge University Press.

Nelson, Katherine. 1993. "The Psychological and Social Origins of Autobiographical Memory." Psychological Science 4:7–14.

Rubin, David C.; Rahhal, Tamara A.; and Poon, Leonard W. 1998. "Things Learned in Early Adulthood Are Remembered Best." Memory and Cognition 26:3–19.

Thompson, Charles P.; Skowronski, John J.; Larsen, Steen; and Betz, Andrew. 1996. Autobiographical Memory: Remembering What and Remembering When. New York: Erlbaum.

Tulving, Endel. 1972. "Episodic and Semantic Memory." In Organization of Memory, ed. Endel Tulving and Wayne Donaldson. New York: Academic Press.

Waldfogel, Samuel. 1949. "The Frequency and Affective Character of Childhood Memories." Psychological Monographs 62 (whole no. 291).

Walker, W. Richard; Vogl, Rodney J.; and Thompson, Charles P. 1997. "Autobiographical Memory: Unpleasantness Fades Faster than Pleasantness over Time." Applied CognitivePsychology 11:399–413.

Charles P. Thompson

DEVELOPMENT OF

Traditionally, the construct of memory has been divided into a number of different types, defined largely in terms of the length of time over which information is retained or stored. For example, memory is divided into a very brief (on the order of milliseconds) sensory store for visual or acoustic properties of a stimulus; short-term or working memory, in which information can be stored and manipulated for about twenty seconds; and long-term memory, in which information can be stored virtually permanently. Long-term memory can be further divided into storage of procedures or skills, such as how to tie a shoe, and storage of explicit or declarative memories, such as memories of personal events or of general knowledge about the world. The study of the development of each of these systems can aid in understanding the cognitive abilities of both children and adults. Because working memory has important implications for learning and education, it is the focus of this entry.

Defining and Measuring Working Memory

Whereas short-term memory refers to the storage of information over brief delays, working memory refers to the capacity to store information for brief periods and to manipulate it during storage. A prominent model of working memory suggests that it is a multicomponent resource consisting of a limited-capacity central executive or "work space," where processing takes place, and two storage components, one for verbal information and one for spatial information. Working memory underlies a variety of complex cognitive tasks, including reading comprehension and mental arithmetic. For example, mentally adding the numbers 12 and 49 requires that both numbers be held in mind as the operation of addition is performed. Because conscious manipulation of information depends on working memory, one must examine its development in order to understand the abilities of different aged children to comprehend, learn, and remember the information taught to them.

Unlike the capacity for long-term memory, which is considered to be virtually unlimited, the capacity for working memory is limited to a few items. Indeed, the increase in the number of items that can be stored and manipulated at a time (referred to as the working memory "span") is a major source of age-related change in working memory. Moreover, at any given age, there are differences among individuals in their working memory spans. Measures of working memory span thus are integral to the study of working memory. Methods of assessing working memory include the reading span task, the A-not-B task, and the imitation task.

The reading span task. A classic measure of working memory in adults is the reading span task. Reading span is assessed by having adults read a series of sentences and then recall the final word of each of the sentences in the order that they read them. The reading span task requires both the storage and manipulation of information: The reader must store the last word of each sentence while reading subsequent words and sentences. Measures have also been developed to assess working memory throughout childhood, and these measures reveal systematic increases in working memory capacity across age.

The A-not-B task. In the second half of the first year of life, working memory most frequently is assessed by the A-not-B task. In the A-not-B task, a small toy is hidden in one of two identical wells (Well A) in full view of the infant. After a brief delay, the infant is allowed to reach into Well A to find the toy. Following several "A" trials, the toy is hidden in the second well (Well B). Even though the infants watch as the toy is hidden in Well B, they often reach to Well A again, making the "A-not-B error." Overcoming the A-not-B error, and thus, successfully searching in Well B, requires that infants (1) remember where they saw the toy hidden (requiring storage of information) and (2) inhibit the learned tendency to reach to Well A (requiring processing of information). As working memory ability increases, infants are able to withstand longer delays without making the A-not-B error. The delay that infants are able to tolerate without making the error increases about two seconds per month between the ages of seven to twelve months.

The imitation task. In the second year of life, working memory can be assessed using imitation. In a standard imitation task designed to assess short-term or long-term memory, props are used to produce a sequence of actions (e.g., making a rattle by putting a ball into a nesting cup [step 1], covering it with another cup [step 2], and shaking the cups to make a rattle [step 3]). The child then is allowed to imitate the sequence either immediately (as a measure of short-term memory) or after a delay (as a measure of long-term memory). To assess working memory, the steps of several sequences are presented in interleaved order. That is, rather than the steps of a single event in sequence (A-1, A-2, A-3, with the alphabetic character referring to the sequence and the number referring to a step in the sequence), the child sees, for example, A-1, B-1, C-1, A-2, B-2, C-2, A-3, B-3, C-3. The child is then provided with the materials for each of the sequences in turn (e.g., all of the materials for sequence A) and is encouraged to produce the sequences. The interleaving of the sequences during presentation requires that the child not only store the information for each individual step but also attend to subsequent steps and integrate the steps into their respective sequences. Researchers have used the imitation task with seventeen- and twenty-month-old children, finding increases in performance, and therefore in working memory, with age.

Tasks for assessing older children. Working memory may be assessed in older children with an adaptation of the reading span task and with a similar task using numbers. Both tasks indicate increases in working memory across the age range of seven to thirteen years. In addition, children with reading disabilities perform at lower levels on both tasks than do their normal age-mates, and children with arithmetic disabilities have trouble with the number task. Thus, working memory plays an important role in the development of reading and number skills during middle childhood. Adult levels of performance on working memory tasks are reached by the high school years.

Factors Affecting Developmental Changes in Working Memory

Developmental changes in working memory may be due to several factors, including brain maturation, increases in the speed of information processing, increases in knowledge, better use of strategies, and more effective management of attention. For example, the processes involved in working memory are largely dependent on the prefrontal cortex of the brain. The prefrontal cortex matures late relative to other brain regions, such as those involved in sensory and motor processes, and does not reach full maturity until adolescence or even early adulthood. Thus, the time courses of development of the functions of working memory and of the brain regions thought to support them are closely linked. Brain maturation also involves a process called myelination, in which a fatty substance surrounds the nerve cells and aids in the conduction of brain impulses. Myelination may increase the speed of processing, thereby increasing working memory abilities as children mature: Faster processing allows for the storage of more information before it decays from working memory.

Other factors that may affect the development of working memory include increased knowledge, strategy use, and management of the focus of attention. Breadth of knowledge affects working memory to the extent that new information can be linked to existing knowledge. For example, it is easier to store nine letters that form three words that are already stored in long-term memory (e.g., p-e-n, d-o-g, ha-t) than to store a list of nine random letters in working memory (e.g., p-o-h-e-d-t-n-g-a). The learning of and increased efficiency in the use of strategies also aids working memory. For example, as children reach the late grade-school years, they begin to spontaneously use rehearsal (the strategy of repeating the information mentally) when they attempt to remember something new. Working memory also develops with age as children gain increasing control over the focus of their attention. This permits them to attend to more information, switch the focus of attention as needed, and inhibit attention to irrelevant information. All three of these factors–increased knowledge, strategy use, and management of attention–likely play a role in the development of working memory throughout childhood.

Summary

Working memory involves the conscious storage and manipulation of information that is integral to the performance of complex cognitive tasks. It is clear that working memory develops throughout childhood, as children are able to hold increasingly more information "online" even as they perform a greater number of mental manipulations on the information. Because working memory underlies so much of mental functioning, it is important to understand its development, as well as the sources and implications of individual differences in it.

See also: Memory, subentry on Myths, Mysteries, and Realities.

bibliography

Baddeley, Alan. 1981. "The Concept of Working Memory: A View of Its Current State and Probable Future Development." Cognition 10:17–23.

Baddeley, Alan, and Hitch, Graham. 1974. "Working Memory." In The Psychology of Learning and Motivation, ed. Gordon A. Bower. New York: Academic Press.

Bauer, Patricia J.; Van Abbema, Dana L.; and DE Haan, Michelle. 1999. "In for the Short Haul: Immediate and Short-Term Remembering and Forgetting by Twenty-Month-Old Children." Infant Behavior and Development 22:321–343.

Bauer, Patricia J.; Wenner, Jennifer A.; Dropik, Patricia L.; and Wewerka, Sandi S. 2000. "Parameters of Remembering and Forgetting in the Transition from Infancy to Early Childhood." Monograph of the Society for Research in Child Development 65 (4).

Case, Robbie D.; Kurland, Midian; and Goldberg, Jill. 1982. "Operational Efficiency and the Growth of Short-Term Memory Span." Journal of Experimental Child Psychology 33:386–404.

Cowan, Nelson. 1997. "The Development of Working Memory." In The Development of Memory in Childhood, ed. Nelson Cowan. Hove, East Sussex, Eng.: Psychology Press.

Daneman, Meredyth, and Carpenter, Patricia. 1980. "Individual Differences in Working Memory and Reading." Journal of Verbal Learning and Verbal Behavior 19:450–466.

Diamond, Adele. 1985. "Development of the Ability to Use Recall to Guide Action, as Indicated by Infants' Performance on A not B." Child Development 56:868–883.

Gathercole, Susan. 1998. "The Development of Memory." Journal of Child Psychology and Psychiatry 39:3–27.

Luciana, Monica, and Nelson, Charles A. 1998."The Functional Emergence of Prefrontally-Guided Working Memory Systems in Four-to Eight-Year-Old Children." Neuropsychologia 36:273–293.

Siegal, Linda S., and Ryan, Ellen B. 1989. "The Development of Working Memory in Normally Achieving and Subtypes of Learning Disabled Children." Child Development 60:973–980.

Starr, Rebecca M.; De Haan, Michelle; and Bauer, Patricia J. 2001. "Piecing It Together: Assessing Working Memory in Preverbal Children." Paper presented at the biennial meeting of the Society for Research in Child Development, Minneapolis, MN.

Patricia J. Bauer

Rebecca M. Starr

GRAPHICS, DIAGRAMS, AND VIDEOS

Graphics, diagrams, and videos are frequently used to enhance learning of verbal material. Indeed, as much as half of the space in K–12 textbooks is devoted to graphics and diagrams, and videos are frequently presented in classrooms. Furthermore, recent technological advances have made possible the use of additional, primarily visual, materials for instruction, such as animation and hypertext.

Presumably, graphics, diagrams, video, and other visual materials are used to make information accessible and memorable. But how might such visual materials be exploited to facilitate learning and memory? When are such displays actually beneficial for learning, and when are they simply decorative or even distracting? This brief review begins with a discussion of general research on how visual media displays aid comprehension and enhance memory for verbal material, and the circumstances in which visual materials are distracting and perhaps even reduce comprehension memory of verbal material. This discussion incorporates guidelines for the design of visual displays for effectively enhancing memory in the context of specific commonly used displays such as graphic organizers, graphs, diagrams, and videos.

Main Benefits of Graphics, Diagrams, and Videos

Visual displays and videos play a number of important roles in learning. Perhaps the most cited cognitive explanation for the benefits of presenting information both visually and verbally is Allan Paivio's dual-coding theory. In classic memory studies, Paivio and his colleagues demonstrated that people were better at remembering lists of words coded visually and verbally, rather than merely verbally. One explanation for the superiority of dualcoding is that by encoding information to be learned in two modalities rather than a single modality, people have multiple retrieval cues that help them access information, thus enhancing memory.

A second general benefit of visuospatial displays is that they are visually appealing. Viewers' attention is attracted to these displays, and viewers are more likely to study them for longer periods of time. This, in turn, can lead to enhancement of memory for information depicted in them. For example, one study of memory for materials taught in introductory psychology courses found that students recalled ideas and examples presented in videos and in-class demonstrations better than information presented in the text alone.

In addition to directly enhancing memory for information, diagrams, graphics, and videos can also make complex information easier to comprehend. Specifically, visual representation can make complex information "visually obvious" and thus require less cognitive effort to understand than text-based descriptions of the same information. Better comprehension, along with more cognitive resources that can be allocated to learning and memory, will together enhance memory for the information to be learned.

Concepts that Visual Displays Are Most Useful in Communicating

Visual displays are particularly beneficial to the comprehension of some classes of concepts that often involve specialized types of displays. First, visual displays are useful for communicating cause- and-effect information. For example, a diagram can help illustrate how turning a key can unlock a door. When such displays are designed to highlight the cause- and-effect sequence (e.g., by animating one portion at a time or by using a sequence of arrows), viewers' comprehension and memory for the cause- and-effect information is enhanced.

Second, visual displays are frequently useful for representing relationships amongst elements (e.g., a Venn diagram, a text-based graphic organizer, a scientific model). One benefit of such representations is that they can facilitate problem solving. Another benefit is that they provide concrete representation of key concepts or elements and their relationships. Graphic organizers, for example, are often used to represent relationships among the main ideas in a text. For example, information in a text can be summarized in matrix form such that similar concepts are closer together along one or more dimensions. Research has suggested that representations that group relevant concepts, such as matrices, can significantly enhance memory for text compared to representations that simply summarize materials, such as outlines. Indeed a general principle that is relevant for any diagram intended to represent relationship elements, including graphic organizers but also including graphs, flowcharts, and so on, is that information that is closely related be placed close together on a page or related visually (e.g., via Gestalt principles of grouping).

Third, visual displays are useful for communicating information that is intrinsically visuospatial. For example, visual displays of a map of a building or a drawing of how different parts of a car engine fit together communicate information that is difficult to describe verbally. Not all intrinsically visuospatial displays, however, are equally beneficial. One general guideline is to design displays that facilitate integrating relevant information (placing text and graphics together) to reduce working memory load and allow viewers to focus on learning relevant content. A 2001 book by Richard Mayer on multimedia learning includes a number of guidelines for the design of such displays.

Fourth, visual displays provide natural mappings to quantitative information (e.g., more is higher) and thus increase comprehension and memory for quantitative information. One difficulty associated with graphs is that students often make interpretation errors and therefore remember erroneous data. In a 2002 article, Priti Shah and James Hoeffner discuss a set of guidelines for teachers and other graph designers who need to depict data for students. These guidelines include making relevant trends visually salient in the graph and writing text to be compatible with information in the graph.

Additional Benefits of Visual Displays

In addition to making some concepts easier to understand, diagrams, graphics, and videos tend to focus viewers' or readers' attention and thus highlight important information. Displays or videos can guide a viewer's attention from one step to the next in a description of causal information or in instructions. For example, a sequence of arrows might highlight how a mechanical device, such as a bicycle pump or a toilet, works, or a sequence of panels might instruct someone how to bake cookies. Such displays, by highlighting information or key elements in a sequence, help students learn and remember relevant information.

In addition to the cognitive aspects of how they influence memory, visual displays and videos serve a social function beneficial to memory. In particular, visual displays and videos provide a common motivating experience for students. In "anchored instruction," students view movies with built-in problems that serve as a reference point for lessons on a wide variety of topics such as solving mathematical problems, discussing social issues, and understanding physics concepts. The common anchor may provide a social and personal context for information to be learned.

The use of graphics, diagrams, and videos includes not just presenting such visual information to students but also asking them to create them. Creating visual artifacts or inscriptions appears to be motivating to students, especially when they share their products with fellow students. Furthermore, developing them forces students to consider the important elements and relationships and also to identify what information they understand and what they do not. Thus, the creation of graphics, diagrams, and videos can be used to enhance comprehension and memory for to-be-learned information.

Drawbacks of Displays and Videos

Despite the benefits of graphics, diagrams, and videos for helping students comprehend and remember important information, there are some cases in which displays and videos can be harmful. Specifically, because graphics, diagrams, and videos attract attention, it is possible that in many cases such visual presentations serve as seductive details detracting attention from important information and thus impair rather than enhance learning. A concrete example of a display that may serve as a seductive detail is a picture, in a scientific text about how lightning is formed, of someone who was struck by lightning. Although the intention of such a picture might be to interest the students in the content of the text, research has found that, in fact, displays such as these are actually distracting and reduce the quality of readers' understanding of the scientific content of the text. Videos, also, can serve as or include seductive details detracting viewers from the main message of a particular lesson.

In summary, this general discussion of visual displays suggests that diagrams, graphics, and videos can help users comprehend relevant information and enhance memory for that information. The content and format of the information, however, should be consistent with the goals of communication. When the content is not consistent with the goals of communication, students may remember irrelevant or inaccurate information.

See also: Literacy, subentry on Learning from Multimedia Sources; Media and Learning; Reading, subentry on Content Areas.

bibliography

Clark, James M., and Paivio, Allan. 1991. "Dual Coding Theory and Education." Educational Psychology Review 3:149–210.

Larkin, Jill H., and Simon, Herbert A. 1987. "Why a Diagram Is (Sometimes) Worth Ten Thousand Words." Cognitive Science 11:65–99.

Mayer, Richard E. 1993. "Illustrations that Instruct." In Advances in Instructional Psychology, ed. Robert Glaser. Hillsdale, NJ: Erlbaum.

Mayer, Richard E. 2001. Multimedia Learning. New York: Cambridge University Press.

Mayer, Richard E.; Heiser, Julie; and Lonn, Steve. 2001. "Cognitive Constraints on Multimedia Learning: When Presenting More Material Results in Less Understanding." Journal of Educational Psychology 93:187–198.

Michas, Irene C., and Berry, Dianne C. 2001. "Learning a Procedural Task: Effectiveness of Multimedia Presentations." Applied Cognitive Psychology 14:555–575.

Oestermeier, Uwe, and Hesse, Friedrich W. 2000. "Verbal and Visual Causal Arguments." Cognition 75:65–104.

Robinson, Daniel H. 2002. Educational Psychology Review 14 (Special issue on text adjuncts).

Robinson, Daniel H., and Skinner, Christopher H. 1996. "Why Graphic Organizers Facilitate Search Processes: Fewer Words or Computationally Efficient Indexing?" Contemporary Educational Psychology 21:166–180.

Shah, Priti, and Hoeffner, James. 2002. "Review of Graph Comprehension Research: Implications for Instruction." Educational Psychology Review 14:47–49.

Vanderbilt University. The Cognition AND Technology Group at Vanderbilt. 1997. The Jasper Project: Lessons in Curriculum, Instruction, Assessment, and Professional Development. Mahwah, NJ: Erlbaum.

Vanderstoep, Scott W.; Fagerlin, Angela; and Feenstra, Jennifer S. 2000. "What Do Students Remember from Introductory Psychology?" Teaching of Psychology 27:89–92.

Priti Shah

IMPLICIT MEMORY

Implicit memory refers to the expression of past events on current behavior when people are not trying to retrieve these past events and when they are usually not even aware of the events' influence. This process is different from explicit memory, which refers to conscious attempts to retrieve memories of past events; in implicit memory tests there is no conscious effort to retrieve. The customary use of the terms memory or remembering refers to explicit, conscious recollection during which people attempt to travel back in time to mentally relive or reexperience past events. Many behaviors people perform, however, reflect past learning even when they are not consciously attempting to retrieve; therefore, these behaviors reflect the manifestation of implicit memory. Some of these behaviors involve motor skills. When people tie their shoes or ride a bicycle or walk, they need not consciously retrieve their first attempts to learn these skills. The same is true of other types of learning. It is much easier to read a passage of text that one has read before, even if not consciously trying to remember the original time the passage was read. As these examples indicate, implicit learning is sometimes referred to as occurring rather automatically or at least to having an automatic component.

As a Reflection of Conscious Learning

Implicit memory measures are sometimes said to reflect unconscious learning because densely amnesic brain-damaged patients typically show intact uses of implicit memory. The data in Figure 1 are from a 1984 experiment by Peter Graf, Larry Squire, and George Mandler. They compared brain-damaged participants who displayed serious impairments on explicit memory tests such as recall and recognition to age- and education-matched control participants. In one test condition, both groups of participants studied lists of words and attempted to recall them in any order (free recall). As can be noted on the left of the graph in Figure 1, the patients recalled the words much worse than did the controls. This pattern reflects the patients' deficit on an explicit memory test, in which they were asked to consciously retrieve past events.

In the implicit test, both groups studied the lists of words but were tested by being shown three-letter stems of words with the instruction to produce the first word that came to mind in response to each stem clue. So, if the word chair had been in the list, participants would get cha and be asked to say the first word that came to mind (chain, chapter, challenge and so on–each stem had at least ten possible

FIGURE 1

completions). If chair had not been presented in the list, people in both groups produced it about 10 percent of the time (the dashed line on the right side of Figure 1). However, if chai had been presented in the list, both patients and the control participants produced the word about 45 percent of the time. The fact that both groups completed the word so much above the base rate reflects priming, the basic measure of implicit memory tests. Priming is defined as the difference between performance on a test when the relevant information has been presented and performance when the relevant information has not been recently presented. Therefore, the amount of priming reflected in the data in Figure 1 was about 35 percent (45% in the primed condition minus the 10% base rate). Although the participants were told to produce any word that came to mind, the presentation of chair in the list primed them to produce that word rather than another on the test.

This priming effect reflects a use of memory, but not a conscious or intentional use of memory. Because the patients were densely amnesic and probably did not remember even studying the list of words, the priming may be said to be unconscious (in this sense). The amnesic patients produced just as much priming as did control participants. Because the patients had suffered brain damage that impaired their use of explicit memory processes, it appears that the brain mechanisms and processes that underlie explicit and implicit memory tests are quite different. Put another way, the results show that memory is not a unitary entity; people with certain types of brain damage can be severely impaired on one type of memory test and unaffected on other types of tests.

Implicit Memory Tests

The study of implicit memory began in psychology in the early 1980s and in the early twenty-first century there is a large amount of literature on the topic. There seem to be at least two distinct types of implicit memory tests, perceptual and conceptual.

Perceptual memory tests. Perceptual implicit memory tests challenge the perceptual system by presenting impoverished test stimuli to which participants respond. The word stem completion test already described (cha ) is one such test. Others are word identification (presenting words very briefly and having participants guess what they are), and word fragment completion (naming words from fragments such as l_p_a_t. (That fragment is hard if not recently primed [with word elephant ].) If pictures are used as study materials, then the test can involve giving fragmented forms of pictures or having them be gradually clarified through a series of successively fuller fragments until the participant can identify the picture. Again, the measure in all cases is priming–as reflected by more accurate or faster completion of the target when it has been studied relative to when it has not been studied.

Factors that greatly affect priming on perceptual implicit memory tests are often quite different from those that affect performance on most explicit memory tests in both patients and in healthy control participants, indicating further that these two types of tests seem to be measuring different processes. For example, modality of presentation of words strongly affects performance on perceptual implicit tests. Visual presentation of words enhances priming on visual tests, whereas auditory presentation enhances priming on auditory implicit tests (e.g., presenting words describing noise with auditory cues for identification). Modality generally matters little in tests of explicit memory. On the other hand, factors that can have a great effect on explicit memory tests can have little or no effect on priming on implicit tests. For example, when participants read pairs of words (hot and cold ) or generate the second word from a clue such as "opposite of cold," they scored better on an explicit test of recognition for the words they generated, but exhibited more priming for the words they just read on an implicit test, in which they had to quickly identify the word. The data are shown in Figure 2.

The results described above can be explained, at a general level, by the theory of transfer appropriate processing. This principle states that performance on memory tests will be enhanced if there is a match between the conditions of study and test, which will permit the study experience to transfer better to the test. For example, if the test involves deciphering a fragmented or briefly presented word given visually (classified as a perceptual test), then performance on this test should benefit from prior visual presentation more than from a prior auditory presentation or from generating the word, as is indeed the case. Practice reading a visual word (versus hearing or generating it) transfers better to a test that also involves reading words.

Conceptually driven tests. Whereas most implicit tests depend on perceptual processing, most explicit memory tests depend heavily on the meaning of the concepts or events that are being remembered. These tests are called conceptually driven tests because, when people are trying to retrieve past events, it is the meaning of the events that is important. Generating a word involves more attention to meaning than simply reading it, and so generating produced greater explicit recognition in results shown in Figure 2. Again, this finding is in accord with the transfer appropriate processing theory. The transfer appropriate processing theory can account for a large body of findings although some problems remain.

Although explicit memory tests are usually driven by meaning or by conceptual information, there is a class of implicit memory tests that is also conceptually driven. These tests are probably the most relevant for education, but they have not yet been studied as much as perceptual implicit tests. One class of conceptual implicit memory tests that has been studied is the general knowledge test. "What animal did Hannibal use to help him cross the Alps in his attack on Rome?" and "What is the name of the ship that carried the pilgrims to America in 1620?" are examples of questions on general knowledge tests. Prior exposure to the words elephant or Mayflower before the questions are asked increases correct answers to these questions, which reflects priming of concepts. Free association tests ("say the first word that you think of to the stimulus word tusk ") and category association tests ("list as many African animals as you can in thirty seconds") are other examples of conceptually driven implicit memory tests. These priming effects again seem to be indicative of implicit retrieval because they also appear in brain-damaged patients with severe difficulties in explicit expressions of memory.

In some sense, much of education is intended to permit people the automatic, unconscious retrieval of facts, routines, and principles when they need them. Education is meant to provide learning experiences that will, at least in some cases, last a lifetime. Of course, not all facts and principles will be remembered for that long. Much information learned in the classroom will be forgotten (at least when explicit tests are given). The hope is that one's general knowledge and skills (writing, thinking logically)

FIGURE 2

will survive. There are no studies of residual, implicit retention of formal education but such studies will surely come in the future.

See also: Memory, subentries on Myths, Mysteries, and Realities, Structures and Functions.

bibliography

Blaxton, Teresa A. 1989. "Investigating Dissociations among Memory Measures: Support for a Transfer-Appropriate Processing Framework." Journal of Experimental Psychology: Learning, Memory, and Cognition 15:657–668.

Gardiner, Howard; Boller, Francois; Moreines, Judith; and Butters, Nelson. 1973. "Retrieving Information from Korsakoff Patients: Effects of Categorical Cues and Reference to the Task." Cortex 9:165–175.

Graf, Peter; Squire, Larry R.; and Mandler, George. 1984. "The Information that Amnesic Patients Do Not Forget." Journal of Experimental Psychology: Learning, Memory, and Cognition 10:164–178.

Jacoby, Larry L. 1983. "Remembering the Data: Analyzing Interactive Processes in Reading." Journal of Verbal Learning and Verbal Behavior 22:485–508.

Jacoby, Larry L., and Dallas, Mark. 1981. "On the Relationship between Autobiographical Memory and Perceptual Learning." Journal of Experimental Psychology: General 110:306–340.

McDermott, Kathleen B., and Roediger, Henry L. 1996. "Exact and Conceptual Repetition Dissociates Conceptual Memory Tests: Problems for Transfer Appropriate Processing Theory." Canadian Journal of Experimental Psychology 50:57–71.

Roediger, Henry L. 1990. "Implicit Memory: Retention without Remembering." American Psychologist 45:1043–1056.

Roediger, Henry L., and McDermott, Kathleen B. 1993. "Implicit Memory in Normal Human Subjects." In Handbook of Neuropsychology, ed. François Boller and Jordan Grafman. Amsterdam: Elsevier.

Schacter, Daniel L. 1987. "Implicit Memory: History And Current Status." Journal of Experimental Psychology: Learning, Memory, and Cognition 13:501–518.

Squire, Larry R. 1987. Memory and the Brain. New York: Oxford University Press.

Tulving, Endel. 1985. "How Many Memory Systems Are There?" American Psychologist 40:385–398.

Vaidya, Chandan J.; Gabrieli, John D. E.; Keane, Margaret M.; and Monti, Laura A. 1995. "Perceptual and Conceptual Memory Processes in Global Amnesia." Neuropsychology 9:580–591.

Henry L. Roediger III

Lisa Geraci

MENTAL MODELS

Mental models, also called situation models, are mental representations of the state of affairs in a real or possible world. They serve as mental simulations of events. For reading, a mental model represents the situation described by the text rather than the text itself. The creation of a coherent mental model is the goal of comprehension.

Mental models are complex representations that contain many different types of information. This includes a spatial-temporal framework about the spatial context in which an event occurred and the time period in which the event transpired (i.e., where and when it occurred). They also contain tokens to represent entities, such as people, animals, objects, and ideas. These tokens might have properties associated with them, such as physical characteristics, emotions, or names. Within a framework there may be structural relations that define the event. This can include spatial relations (e.g., the umpire is behind home plate), ownership relations (e.g., the players are using the shortstop's ball), social relations (e.g., the two teams are bitter rivals), and so forth. Finally, because events are dynamic, several frameworks can be joined by linking relations that contain temporal order and causal information.

The Role of Experience

Mental model creation involves integrating prior knowledge with what has been given. This allows inferences to be drawn for information that has not been provided. Of course, the more knowledge a person has, the more likely it is that an adequate mental model will be constructed. For example, when watching a baseball game, a person with a lot of baseball knowledge will better understand the structure of the game, the causal and goal-related relations among the players, and the sequence of events.

The structure of one's experience influences the creation of mental models. Suppose a person reads a text on a topic that the reader has a fair amount of knowledge of, such as going to a baseball game. In this case, there is a certain sequence in which the events occur (e.g., buying a ticket before finding one's seat). Even if two events are adjacent in the text, reading times increase as the distance between them in the standard sequence increases. So when building mental models, people consult their knowledge systematically. It is as if they are scanning sequentially through their knowledge to assess where the current events fit. The greater the distance, the longer the scanning process and the more that needs to be inferred.

Mental models are essentially an amalgam of the given information that can be acquired through a film, book, lecture, discussion, and so forth, along with prior knowledge that a person has in long-term memory. The use of mental models is found in a wide variety of circumstances, including language comprehension and memory.

Comprehension

Mental models are critical for understanding. When people comprehend language, they create three types of mental representations. The simplest is a verbatim representation of what was heard or read. This is forgotten very quickly unless there is something important about the exact wording, as with a joke. At a more abstract level is the propositional textbase. This is a representation of the idea units that were expressed. For example, the sentences "The ball was hit by the batter" and "The batter hit the ball" would correspond to the same propositional representation. This representation is forgotten less rapidly. Finally, at the most abstract and highest level is the mental model. This is a referential representation of the described events. The mental model is a representation of what the message is about. In contrast, the verbatim and textbase levels are representations of the message itself but may serve as scaffolding from which to build a mental model.

While the goal of comprehension is to construct a mental model, its organization and function can influence comprehension itself. During reading, people keep track of what is going on in the described situation. For example, readers may keep track of the spatial location of a protagonist in a story. When that person moves from one location to another, knowledge about people or objects in the old location become less available. Switching from one spatial framework to another influences what information is readily available during comprehension. Moreover, the further the protagonist moves from the original location, the less available the information becomes. A similar thing occurs for temporal frameworks. Short time periods are more likely to be part of the same time frame, whereas long time periods are more likely to include a shift to a new time frame, and hence a new situation. Information that was relevant to the original situation is less available after a large time shift. Finally, people also monitor a protagonist's goals. Information that is relevant to current, unsatisfied goals is more available than information relating to goals that were successfully completed. The prior goal information is no longer maintained in the current mental model.

When the structure of the situation changes, reading times increase, as if readers are monitoring the described events. This includes changes in space, time, entities, causality, or the goals of the protagonist. When a major change in the described situation occurs, people update their mental models. In addition to monitoring event changes, people may also notice inconsistencies with what has been described before. Such inconsistencies result in increased reading times as the reader tries to resolve what they know of the situation with the current information.

One of the most important dimensions that people monitor is causality. Information varies in the degree of its causal importance. Information that plays an active role in the described situation is causally more important. Such information is typically read more quickly. Presumably, this is because it can be more easily integrated into the current mental model.

Memory

Mental models are also involved in memory. At very long periods of time, this is the representation that will dominate a person's recollections. Many of the influences during comprehension carry over into memory. For example, shifts in a situation during comprehension result in the memory being organized around those shifts. Also, causally important parts of an event are better remembered than less important parts. It should be noted that the ease with which information is integrated into a mental model has an influence on the ability to identify that situation later. Continuous and consistent descriptions are remembered better than discontinuous, inconsistent descriptions.

Mental models include both given information and inferences a person generates. With the passage of time, it becomes difficult to disentangle these two. People often mistakenly identify information as having been encountered before if it is consistent with the previously described situation, even when that information is new.

How information refers to the world is important for how it is represented in mental models. This has important consequences for memory. When given a large set of related information, a person can integrate this information into one mental model if the information can be interpreted as being consistent with a single situation in the world. Otherwise, it may be stored in separate mental models. When a person needs to remember one piece of information, if there are related mental models containing related but irrelevant information, this will produce interference, causing the memory retrieval to be slower and more error prone. If, however, the information is integrated into a single model, there is no such cost to memory.

While these findings suggest that a mental model can influence memory retrieval, it is also possible to remove these influences to a certain degree. As mentioned earlier, people create multiple representations during comprehension, including verbatim, propositional, and mental model representations. The mental model will contain many inferences and will also capture the perspective of the comprehender. If the mental model is discredited in some way, such as asking a person to take a different perspective on the text that was read, then the person will rely less on the mental model and more on the propositional representation. For example, people reading a description of a baseball game might originally be told that the home team was going to make the playoffs. Then when the person is asked to recall the story, they could be told that the story was about a team that ended up in last place. This shift in perspective will cause a decrease in the number of inferences a person reports and also increase memory for those previously unremembered propositions that are consistent with the new perspective. Thus, the person has disregarded their mental model during memory retrieval.

Summary

Mental models are mental representations of specific states of affairs in the world. They are created using the knowledge a person has at hand, along with prior knowledge. The organization and extensiveness of this prior knowledge is of great importance. People use mental models during comprehension as the basis for their understanding. Changes in the described situations cause people to update their mental models, which has a tangible effect on the comprehension process itself. Finally, mental models appear to be the form of mental representation that is stored in memory for long periods of time. The ability of a person to remember information in part reflects the organization and structuring of information into mental model.

See also: Learning, subentry on Knowledge Acquisition, Representation, and Organization; Reading, subentry on Comprehension.

bibliography

Albrecht, Jason E., and O'Brien, Edward J. 1995. "Goal Processing and the Maintenance of Global Coherence." In Sources of Coherence in Reading, ed. Robert F. Lorch and Edward J. O'Brien. Hillsdale, NJ: Erlbaum.

Bower, Gordon H.; Black, John B.; and Turner, Terrence J. 1979. "Scripts in Memory for Text." Cognitive Psychology 11:177–220.

Garnham, Alan. 1982. "Situation Models as Representations of Text." Memory and Cognition 9:560–565.

Hasher, Lynn, and Griffin, Mary. 1978. "Reconstructive and Reproductive Processing in Memory." Journal of Experimental Psychology: Human Learning and Memory 4:318–330.

Johnson-Laird, Philip N. 1983. Mental Models: Towards a Cognitive Science of Language, Inference, and Consciousness. Cambridge, MA: Harvard University Press.

Morrow, Daniel G.; Greenspan, Steven L.; and Bower, Gordon H. 1987. "Accessibility and Situation Models in Narrative Comprehension." Journal of Memory and Language 26:165–187.

Radvansky, Gabriel A., and Copeland, David E. 2000. "Functionality and Spatial Relations in Situation Models." Memory and Cognition 28:987–992.

Radvansky, Gabriel A., and Zacks, Rose T. 1991. "Mental Models and the Fan Effect." Journal of Experimental Psychology: Learning, Memory, and Cognition 17:940–953.

Suh, Soo Y., and Trabasso, Thomas. 1993. "Inferences during Reading: Converging Evidence from Discourse Analysis, Talk-Aloud Protocols, and Recognition Priming." Journal of Memoryand Language 32:279–300.

Van Dijk, Tien A., and Kintsch, Walter. 1983. Strategies in Discourse Comprehension. New York: Academic Press.

Zwaan, Rolf A. 1996. "Processing Narrative Time Shifts." Journal of Experimental Psychology: Learning, Memory, and Cognition 22:1,196–1,207.

Zwaan, Rolf A.; Magliano, Joseph P.; and Graesser, Arthur C. 1995. "Dimensions of Situation Model Construction in Narrative Comprehension." Journal of Experimental Psychology: Learning, Memory, and Cognition 21:386–397.

Zwaan, Rolf A., and Radvansky, Gabriel A. 1998. "Situation Models in Language Comprehension and Memory." Psychological Bulletin 123:162–185.

Gabriel A. Radvansky

David E. Copeland

METAMEMORY

Metamemory refers to a person's knowledge about the contents and regulation of memory. The term originally derives from the work of John H. Flavell in the early 1970s. Metamemory enables a person to reflect on and monitor her memory. In addition, metamemorial knowledge plays an important role in planning, allocation of cognitive resources, strategy selection, comprehension monitoring, and evaluation of performance.

This entry begins with a description of the two main structural components of metamemory–declarative knowledge, which enables a person to evaluate the contents of memory, and procedural knowledge, which enables a person to monitor and regulate memory performance. It next summarizes important developmental trends in metamemory, then discusses several important educational implications of metamemory research, including the relationships among metamemory, strategy instruction, and self-regulation.

Declarative and Procedural Aspects of Metamemory

Most theorists distinguish between declarative and procedural components of metamemory. The declarative component corresponds to statable knowledge about the contents and contexts of memory use and includes knowledge of memory's contents, knowledge of essential intellectual tasks such as reading and problem solving, and conditional knowledge about why and when strategies are most effective. The procedural component includes knowledge about procedural skills necessary to manage memory efficiently, including control processes such as planning and evaluating and monitoring processes such as judgments of learning. Some theorists, but especially those interested in the relationship between metamemory and social cognition, have proposed a third component, usually referred to as a beliefs component, that regulates affect, social cognition, and efficacy judgments of memory performance. The focus here, however, is on the declarative and procedural components.

The declarative component includes at least three distinct subcomponents: knowledge of contents and capacity, knowledge of tasks, and conditional knowledge about optimal memory performance. The content subcomponent enables a person to assess whether he possesses enough knowledge to meet task demands. The task subcomponent allows a person to determine whether he fully understands task demands and possesses adequate resources to perform the task. The conditional knowledge subcomponent, which many view as the most important of the three, helps a person determine why, when, and where to use a particular strategy or under what conditions he is most likely to achieve optimal performance. Conditional knowledge plays an especially important role in self-regulation.

The procedural component includes control and monitoring subcomponents. The control subcomponent includes regulatory processes such as planning, selection of relevant information, resource allocation decisions, selection of relevant strategies, and inferencing. The monitoring subcomponent includes a variety of self-assessment strategies such as ease-of-learning judgments, judgments of learning prior to beginning a task, feeling-of-knowing judgments made during learning, and comprehension-monitoring judgments made during or after a task. Most theories of metamemory assume that control processes directly regulate cognition and performance, whereas monitoring processes inform the precision of control decisions. Thus, control processes are at a higher level than monitoring processes, even though both reciprocally inform one another.

Development of Metamemory

A number of researchers have studied the development of metamemory, and four main conclusions can be drawn from this research. The first conclusion is that metamemory awareness is rather poor in children until the age of ten or older. Younger children frequently find it difficult to monitor the contents of memory, estimate the resources needed to complete a task, select appropriate strategies for a task, and monitor their learning. As a consequence, self-regulation is quite poor among children younger than ten years of age. Even among adults, however, metamemory awareness is poor, sometimes leading to overconfidence and illusions of knowing.

A second conclusion is that metamemory development is incremental and continuous. Development appears to be linear in nature with a steady increase in metamemory awareness, control, and monitoring from preschool through early puberty. Research generally does not reveal significant breaks or jumps in metamemory ability, suggesting continuous development over a ten-year period from early childhood through adolescence. It is less clear whether metamemory awareness continues to develop in adults, although most research indicates that awareness increases within specific domains as expertise develops.

A third conclusion is that metamemorial knowledge is self-constructed in nature through individual and interactive problem solving, as well as explicit strategy instruction and monitoring training. One essential element of the construction process is self-generated and other-generated feedback that increases knowledge of the contents of memory and tasks. A second essential element is modeling, in which an individual has the opportunity to observe and emulate skilled models. Thus far, researchers have failed to detect a strong link between metamemory and either intellectual ability or traditional measures of working memory speed and capacity. This suggests that metamemory awareness develops independent of other individual differences in memory.

The final conclusion is that metamemory facilitates strategy use and performance. For example, correlations between metamemory and memory performance typically range from .30 to .50, even in younger children between the ages of five and ten years. The correlation may be even stronger in adults and experts. Knowledge about the contents of one's memory as well as tasks clearly should affect performance. In addition, declarative knowledge appears to be correlated with regulatory awareness. The more one knows about memory, the better able one is to regulate one's performance.

Metamemory and Learning

Metamemory affects learning in many ways but especially with respect to the efficient use of limited cognitive resources, strategy use, and comprehension monitoring. Children and adults often experience difficulty learning because of cognitive overload–that is, too much mental work to do and too few cognitive resources at their disposal. Research reveals that declarative and procedural knowledge enables learners to use available resources more efficiently because they are better able to plan, sequence, and monitor learning tasks.

A second way that metamemory improves learning is through the flexible use of cognitive learning strategies. Research indicates that self-regulated learners use a diverse repertoire of strategies that are controlled using conditional knowledge in metamemory. Strategy use is highly correlated with skilled problem solving. Research also suggests that strategy training increases metamemory awareness, provided that conditional knowledge about the strategies is embedded within the instruction. In 1999 Roger Bruning, Gregg Schraw, and Royce Ronning provided a step-by-step summary of cognitive strategy instruction that includes feedback and modeling from peers, tutors, and teachers. Strategy instruction is especially effective for helping students develop conditional knowledge that enables them to select the most appropriate strategy and monitor its usefulness.

A third way that metamemory improves learning is comprehension monitoring. Unfortunately, many children and adults do not monitor with a high degree of accuracy. Monitoring training helps learners monitor more successfully and also improves performance. Strategy instruction also improves monitoring even when monitoring instruction is not included as part of the instruction. Thus, either strategy instruction or monitoring training improve monitoring accuracy. Combining strategy instruction and monitoring training within the same intervention helps learners construct the control and monitoring subcomponents of regulatory knowledge described above.

Classroom Implications

Metamemory research has not had a major impact on classroom instruction. The research suggests, however, that children acquire and construct metamemory knowledge in three distinct ways. One way is hands-on experience that provides declarative knowledge about tasks as well as procedural knowledge about optimal performance. A second way is through skilled models who provide detailed feedback–especially conditional feedback–that enables the student to distinguish between effective and less-effective strategies. A third way is through self-reflection and group reflection in which students explicitly discuss the effectiveness of different strategies and ways to improve performance in the future. Thus, there are many ways to improve metamemory awareness through classroom activities.

Several learning interventions have been developed that promote metamemory development and awareness. For example, in 1984 Annemarie S. Palincsar and Ann L. Brown described a program of reciprocal teaching that promotes the self-regulation of metamemory strategies. The program involves the teacher gradually handing over control of reading processes to the student in a small-group format. The teacher first models effective strategies (e.g., finding the main idea of a passage) then provides scaffolding to the students as they attempt to do the same while receiving feedback from their peers regarding the strategies they employ.

Summary

Metamemory is knowledge about memory. Metamemory awareness develops late and incrementally yet has an important impact on memory and cognitive performance. Metamemory is not linked strongly to other cognitive factors such as intelligence and memory capacity. Rather, it develops as a function of experience, guided modeling and feedback, and individual and group reflection.

See also: Learning to Learn and Metacognition; Reading, subentry on Comprehension.

bibliography

Alexander, Joyce M.; Carr, Martha; and Schwanenflugel, Paula J. 1995. "Development of Metacognition in Gifted Children: Directions for Future Research." Developmental Review 15:1–37.

Bruning, Roger H.; Schraw, Gregg; and Ronning, Royce R. 1999. Cognitive Psychology and Instruction, 3rd edition. Upper Saddle River, NJ: Prentice Hall.

Butler, Deborah L., and Winne, Philip H. 1995. "Feedback and Self-Regulated Learning: A Theoretical Synthesis." Review of Educational Re-search 65:245–282.

Dixon, Roger A. 2000. "The Concept of Metamemory: Cognitive, Developmental, and Clinical Issues." In Memory Disorders in Psychiatric Practice, ed. German E. Berrios and John R. Hodges. New York: Cambridge University Press.

Flavell, John H. 1971. "First Discussant's Comments: What Is Memory Development the Development Of?" Human Development 14:272–278.

Metcalfe, Janet. 2000. "Metamemory: Theory and Data." In The Oxford Handbook of Memory, ed. Endel Tulving and Fergus Craik. New York: Oxford University Press.

Nelson, Thomas O., and Narens, Louis. 1994. "Why Investigate Metacognition?" In Metacognition: Knowing about Knowing, ed. Janet Metcalfe and Arthur P. Shimamura. Cambridge, MA: MIT Press.

Palincsar, Annemarie S., and Brown, Ann L. 1984. "Reciprocal Teaching of Comprehension-Fostering and Comprehension-Monitoring Activities." Cognition and Instruction 1:117–175.

Schneider, Wolfgang. 1999. "The Development of Metamemory in Children." In Attention and Performance XVII: Cognitive Regulation of Performance, ed. Daniel Gopher and Asher Koriat. Cambridge, MA: MIT Press.

Schneider, Wolfgang, and Pressley, Michael. 1997. Memory Development between Two and Twenty, 2nd edition. Mahwah, NJ: Erlbaum.

Schraw, Gregg. 2001. "Promoting General Metacognitive Awareness." In Metacognition in Learning and Instruction, ed. Hope J. Hartman. Norwell, MA: Kluwer.

Schraw, Gregg, and Moshman, David. 1995. "Metacognitive Theories." Educational Psychology Review 7:351–372.

Stone, N. J. 2000. "Exploring the Relationship between Calibration and Self-Regulated Learning." Educational Psychology Review 12:437–476.

Sweller, John; Van Merrienboer, Jeroen J.; and Paas, Fred G. 1998. "Cognitive Architecture and Instructional Design." Educational Psychology Review 10:251–296.

Gregory Schraw

John Nietfeld

MYTHS, MYSTERIES, AND REALITIES

Why is it that people remember some things and forget others? How long do people remember things? What kinds of cues are likely to help a person remember a forgotten item? These are just a few of the many questions of interest to memory researchers. This entry reviews some of the important questions in the field of memory research and describes how psychologists use experimental methods to answer these questions. It also describes some of the major findings and rebuts some of the common myths about memory. This discussion is structured around the three stages of memory: encoding, storage, and retrieval.

Encoding refers to the intake of information and creation of a memory trace. In a typical memory experiment, the encoding phase involves presentation of the to-be-remembered stimuli, such as nonsense syllables, words, pictures, stories, films, or staged events. In real life, encoding includes all forms of perception, from watching a movie to having a conversation. Encoding may be intentional in that subjects are forewarned to memorize the items or incidental in that subjects learn the to-beremembered material through performance of another task such as making a category judgment. In educational settings, encoding is intentional when students deliberately study the meanings of vocabulary words, learn facts for a test, or memorize a famous speech. In everyday life, however, most things are learned incidentally. Examples in the education domain include students learning about a historical period by watching films, role-playing, and reading memoirs.

Storage or retention refers to the maintenance of the memory trace over time. In most laboratory experiments, the retention interval is quite short and the subject does an unrelated task during that time. In the education domain, there may be a retention interval of several weeks between learning and testing; students may continue to practice the target information during the retention interval.

Retrieval involves later accessing that memory trace. There are many different ways to test memory. Explicit tests require subjects to consciously remember events from the study phase. Most educational tests are explicit; students know they are being tested and that they should remember facts from class and textbooks. Explicit educational tests include essay, short-answer, multiple-choice, and true-false tests; these roughly correspond to the laboratory tests of free recall, cued recall, forced choice, and old-new recognition. Implicit tests measure the effect of previous experience on a task that does not require the subject to consciously refer back to the study phase. In education, pure implicit tests are rare although many explicit tests may tap a student's implicit knowledge (e.g., essay tests implicitly test a student's knowledge of grammar). In the laboratory, there are many different implicit tests. For example, a subject who had recently seen a list that included the word octopus would complete the word stem "oct—" with "octopus" at a higher rate than subjects who had not seen the list.

In the following sections, some of the facts and myths associated with each of the three stages of memory are described.

Encoding

Key questions about encoding include what kinds of things are easily memorized and what study strategies can be employed to ensure later memory.

Not all materials are remembered equally well. Pictures are remembered better than words, and in general memory is better for distinctive items. Likewise, concrete words are better remembered than abstract words. Good teachers often apply this finding by using concrete analogies to explain abstract phenomena or theories, such as when the movement of gas molecules is compared to the movement of billiard balls on a pool table.

Not all study strategies are equal. In general, elaborative encoding yields the best memory. Elaboration involves going beyond the stimulus at hand to create a richer memory trace. For example, rather than simply repeating a to-be-memorized vocabulary word, a student might think of other words similar in sound and meaning, draw a picture that somehow represents the word and its definition, or write sentences using the word in context. In perhaps the most famous laboratory demonstration of this, Fergus I. M. Craik and Endel Tulving looked at subjects' memory for words after perceptual, phonemic, or semantic processing in a 1975 study. For example, if all subjects studied the word EAGLE, one group decided if the word was in uppercase letters (perceptual), the second group decided if it rhymed with legal (phonemic), and the third group decided if it was an animal (semantic). All of these questions would have been answered affirmatively, but memory was best following semantic processing, next best with phonemic processing, and worst after perceptual processing. This is the classic levels of processing effect. The educational implication is that incidental study can be just as effective as intentional memorization. If students are studying via a semantic or other elaborative task, the resulting memory can be just as strong even if they are not forewarned about the upcoming memory test.

Encoding is not like taking pictures with a camera; not everything is recorded. Instead, encoding is selective. The levels of processing effect is an example of this; depending on the instructions, subjects directed their attention to different features of the target word. More generally, what students encode will be a function of what they already know and how well they can understand and link the incoming information to their prior knowledge. A schema is the term for a person's knowledge representation of a concept or domain. Without a schema, the understanding and interpretation of incoming information is difficult. For example, in a 1977 study by D. James Dooling and Robert E. Christiaansen, subjects had poor memories for such passages as "With hocked gems financing him/our hero bravely defied all scornful laughter that tried to defy his scheme/Your eyes deceive, he said–an egg not a table correctly typifies this unexplored planet." Good memory required knowledge that the upcoming passage would be about Christopher Columbus. Schemas also serve to direct a subject's attention to particular schema-relevant details and to allow for inferences. For example, according to a 1977 study conducted by James Pichert and Richard Anderson, students who read a story about two boys playing hooky and spending the day at home remembered different things depending on which of two perspectives had been instantiated at encoding: home buyer or burglar. Subjects who read the story with the perspective of a burglar attended to and remembered better such details as that the house's side door was unlocked, a fact unlikely to be relevant to a home buyer.

Another fact about encoding is that more is not necessarily better; massed study is not a good idea. While many students choose to cram for exams the night before, the data clearly suggest that spaced study opportunities are preferable. The same holds true for rehearsal of to-be-remembered information, which is described in the next section on activities during the retention interval.

Storage

Encoding is a necessary but not sufficient condition for later memory. As time passes, it becomes less and less likely that a person will be able to retrieve the target event. In 1985 Herman Ebbinghaus first documented the now classic forgetting function; he taught himself series of consonant-vowel-consonant trigams and tested his memory after varying time lags. Memory dropped off quickly at first, but eventually forgetting leveled out over time to a fairly stable level. Most laboratory studies involve fairly short retention intervals; in 1984, however, Harry P. Bahrick examined knowledge of Spanish following retention intervals of up to fifty years (participants reported very little use of Spanish during that time). Again, there was a sharp drop in knowledge by three to six years poststudy, but after that initial drop, knowledge was surprisingly stable over the next twenty-five years. Bahrick termed this long-term retention the permastore.

Rehearsal during the retention interval aids memory; not all forms of rehearsal, however, are equal. Simply repeating a to-be-remembered item will not necessarily lead to enhanced memory. A student who writes a fact over and over will not remember that fact as well as a student who takes a more active approach to rehearsal. One of the best strategies is that of expanding rehearsal combined with self-testing. For example, the student who wants to learn a vocabulary word should not simply stare at the word paired with its definition. Rather, she should test herself and produce the definition of the word from memory; after a short delay she should repeat the process, and so on, incrementally increasing the delay until the retention interval is at the desired length.

Memories do not lie dormant during the retention interval but are affected by the new information that continues to enter the system. In one classic demonstration of interference, subjects saw a slide show of a traffic accident involving a car passing a stop sign. In the next phase of the experiment, subjects in the experimental condition read a narrative description of the slide show that included a misleading reference to a yield sign. Control subjects also read a narrative, but it did not contain the misinformation. All subjects were later asked whether they had seen a stop sign or a yield sign. Subjects who had been exposed to the misleading post-event information were more likely to mistakenly say they had seen a yield sign than the control group. Although the exact mechanisms underlying the misinformation effect are still under debate, in at least some circumstances the misinformation works to block or interfere with access to the original memory.

Retrieval

No single test of memory is perfect. No one test yields an absolute measure of what is in memory; rather, one can ascertain what is accessible only under a particular set of test conditions. The failure to recall part of a list is not necessarily synonymous with forgetting those words. Rather, they may be available in memory but not accessible given the current retrieval cues. When asked to write down all the words from a studied list, a subject may not be able to recall studying the word robin. This allegedly forgotten word, however, may be recalled in response to the category cue "birds" or correctly labeled as "old" on a test that re-presents the word robin for an old-new decision. Similarly, a student who is unable to produce an answer on an essay test may recognize it on a multiple-choice test.

Conclusions about memory may vary across tests. Take, for example, the effects of word frequency on memory. Following study of a word list, words that occur with high frequency in the language (e.g., tree ) are recalled with a higher probability than are words that occur with low frequency in the language (e.g., ecru ). The opposite result, however, is obtained on recognition memory tests. When subjects are asked to label words as "old" or "new," they do a better job with low frequency than high frequency words. This paradox is one that continues to interest researchers.

So, how then to get the best performance possible on a memory test? The general rule is that the test should match study as much as possible. Returning to the levels of processing effect described earlier, semantic processing leads to better memory in part because most memory tests are semantic in nature. When subjects are given a phonological test (e.g., did you study a word that rhymes with beagle ?), performance is better when words are encoded as rhymes than when they are categorized. Effects of test expectancy are nicely explained within this framework. Performance on an open-ended (essay or free recall) test suffers if students are incorrectly led to expect a multiple-choice test. Depending on which test is expected, students study differently. Students expecting a multiple-choice test focus less on relations between items and spend less time preparing than do students expecting a more open-ended test. The way students study for multiple-choice tests does not match the demands of the recall test; hence, performance suffers when students are surprised with the unexpected version of the test. A good educator will make clear the test demands early in a course so that students will tailor their study strategies appropriately.

Memory is not like a tape that can be played back perfectly at test. Rather, memory is reconstructive. In one example of this, from the 1977 study of Dooling and Christiansen, subjects read a paragraph that began "Carol Harris was a problem child from birth. She was wild, stubborn and violent." Right before the test phase, some of the subjects were told that Carol Harris was really Helen Keller. These informed subjects were much more likely to incorrectly identify the statement "She was deaf, dumb, and blind" as having been in the original paragraph than subjects who were not informed of Harris's true identity. Subjects made use of their knowledge at test to reconstruct what they read during the first part of the experiment. Schemas are as active during test taking as they are during encoding, and they provide retrieval cues and allow for reconstruction.

Conclusions

There are two very general requirements for effective memory: quality encoding and appropriate retrieval cues. These principles are exemplified in a classic study method, the SQ3R method, which Francis P. Robinson described in 1970. SQ3R stands for: s urvey, q uestion, r ead, ehearse, and eview. Students begin by surveying the textbook chapter before reading it, to become familiar with its organization. As they read the chapter, they form questions that they then answer. Finally, they rehearse and test themselves on what they have just read, and review all the material repeatedly. Each of these activities links to basic memory processes. The initial survey of the chapter leads students to set up a schema for the chapter that guides both encoding and later retrieval. The questions students create serve as retrieval cues later on. Answering these questions, repeated rehearsing, self-testing, and reviewing the material are all forms of retrieval practice that will aid memory. Studying a textbook chapter need not be a mystery to students.

See also: Memory, subentries on Autobiographical Memory, Implicit Memory, Metamemory, Structures and Functions.

bibliography

Ayers, Michael S., and Reder, Lynne M. 1998. "A Theoretical Review of the Misinformation Effect: Predictions from an Activation-Based Memory Model." Psychonomic Bulletin and Re-view 5:1–21.

Bahrick, Harry P. 1984. "Semantic Memory Content in Permastore: Fifty Years of Memory for Spanish Learned in School." Journal of Experimental Psychology: General 113:1–29.

Craik, Fergus I. M., and Lockhart, Robert S. 1972. "Levels of Processing: A Framework for Memory Research." Journal of Verbal Learning and Verbal Behavior 11:671–684.

Craik, Fergus I. M., and Tulving, Endel. 1975. "Depth of Processing and the Retention of Words in Episodic Memory." Journal of Experimental Psychology: General 104:268–294.

Dempster, Frank N. 1988. "The Spacing Effect: A Case Study in the Failure to Apply the Results of Psychological Research." American Psychologist 43:627–634.

Dooling, D. James, and Christiansen, Robert E. 1977. "Episodic and Semantic Aspects of Memory for Prose." Journal of Experimental Psychology: Human Learning and Memory 3:428–436.

Hall, John F. 1954. "Learning as a Function of Word Frequency." American Journal of Psychology 67:138–140.

Hyde, Thomas S., and Jenkins, James J. 1969. "Differential Effects of Incidental Tasks on the Organization of Recall of a List of Highly Associated Words." Journal of Experimental Psychology 82:472–481.

Kinsbourne, Marcel, and George, James. 1974. "The Mechanism of the Word-Frequency Effect on Recognition Memory." Journal of Verbal Learning and Verbal Behavior 13:63–69.

Loftus, Elizabeth F.; Miller, David G.; and Burns, Helen J. 1978. "Semantic Integration of Verbal Information into a Visual Memory." Journal of Experimental Psychology: Human Learning and Memory 4:19–31.

Morris, C. Donald; Bransford, John D.; and Franks, Jeffrey J. 1977. "Levels of Processing versus Transfer Appropriate Processing." Journal of Verbal Learning and Verbal Behavior 16:519–533.

Pichert, James W., and Anderson, Richard C. 1977. "Taking Different Perspectives on a Story." Journal of Educational Psychology 69:309–315.

Robinson, Francis Pleasant. 1970. Effective Study. New York: Harper and Row.

Rundus, Dewey. 1977. "Maintenance Rehearsal and Single-Level Processing." Journal of Verbal Learning and Verbal Behavior 16:665–681.

Schmidt, Stephen R. 1991. "Can We Have a Distinctive Theory of Memory?" Memory and Cognition 19:523–542.

Tulving, Endel, and Pearlstone, Zena. 1966. "Availability versus Accessibility of Information in Memory for Words." Journal of Verbal Learning and Verbal Behavior 5:381–391.

Tulving, Endel, and Thomson, Donald M. 1973. "Encoding Specificity and Retrieval Processes in Episodic Memory." Psychological Review 80:359–380.

Tversky, Barbara. 1973. "Encoding Processes in Recognition and Recall." Cognitive Psychology 5:275–287.

Whitten, William B., and Bjork, Robert A. 1977. "Learning from Tests: Effects of Spacing." Journal of Verbal Learning and Verbal Behavior 16:465–478.

Elizabeth J. Marsh

STRUCTURES AND FUNCTIONS

In the study of memory there have been many metaphors adopted in the search for an explanation of the memory process. The fourth century b.c.e. Greek philosopher Aristotle compared memorizing to making impressions in wax, and the idea that memories are copies of reality that a person stores and later retrieves has been widespread. This is sometimes called the storehouse metaphor, and many of the ways in which people talk about memory (searching for memories, bringing them back from the recesses of one's mind) assume such a metaphor. The computer metaphor that has been popular with psychologists researching memory is a version of the storehouse view. It conceptualizes the stages involved in remembering in terms of encoding, storage, and retrieval in which information is entered into memory, retained, and then found again at a later time. Thinking about remembering in this way can be valuable, but it can lead to the incorrect assumption that what is remembered is a simple copy of what was originally experienced. In reality, much that is remembered captures the gist rather than the details of the original experience, and remembering is often a process of reconstruction. Examples of constructive remembering can be found in research on false memories. Elaborate and detailed false memories of events from an individual's past can be easily created. More mundanely, hearing a list of close associates to a particular word leads to recall of the word itself even though it was not presented. One alternative to the storehouse metaphor is the correspondence metaphor that emphasizes the deviation between the memory and the original experience.

Memory Structure

Researchers who study memory use a number of terms to subdivide the enormous field. One major distinction is that between explicit and implicit memory. Explicit memory refers to the conscious recall of information. Conscious awareness of past experiences involves explicit memories. Often, however, people are influenced by experiences that are not consciously recallable. For example, the ease and speed with which a person solves the anagram rbocoilc depends upon how recently the person has encountered the word broccoli. This facilitation reflects implicit memory. Processing of new information is primed by past experiences without conscious awareness. The distinction between explicit and implicit memory may reflect different underlying memory systems. Quite different timescales and sensitivities have been demonstrated for some explicit and implicit memory tasks. The differences may arise, however, from the processing requirements of the tasks rather than from different memory systems.

A distinction that overlaps with explicit and implicit memory is that between episodic and semantic memory. This distinction, associated with Endel Tulving, is between memory for events and memory for facts. Episodic memory is for events that people can remember happening, whereas semantic memory is for facts that people know about the world without necessarily retaining any recollection of the situation in which they learned the information. One's memory for eating breakfast on a particular morning is an episodic one, whereas one's memory that Coca-Cola is a drink is a semantic one. One area of episodic memory is autobiographical memory–memory for personal events in one's own life. Autobiographical memories from the first two years of life are very rare, while memories from the late teens and early twenties are more frequently held than the average. Certain autobiographical memories seem to be so distinct and full of the apparently irrelevant details from the original event that they have been called flashbulb memories because the nature of the memory is similar to a photograph of the moment. Archetypal examples of flashbulb memories are associated with hearing or seeing particularly dramatic events such as the assassination of a famous person or a major accident.

Submemories. One approach to understanding the structure of memory has been to seek separate submemories that are responsible for retaining information over differing time periods. In 1968 Richard Atkinson and Richard Shiffrin proposed a model with three types of memory: a sensory store, a short-term store, and a long-term memory. Visual information, for example, is believed to be retained for about one second in a sensory store while perceptual processing takes place. Similar sensory memories aid in the processing of acoustic and other inputs. Beyond the perceptually based sensory memories is the short-term memory, which retains information for a few seconds before selected elements of that information are transferred to a long-term memory. Atkinson and Shiffrin recognized that there were control processes in short-term memory that influence what is attended to and processed. The Atkinson and Shiffrin model has been elaborated into the working memory system, which has been particularly investigated by Alan Baddeley and his colleagues. Baddeley has subdivided the working memory into several subcomponents, the most heavily researched of which are the phonological loop, the visuospatial sketchpad, and the central executive. The phonological loop holds a couple of seconds of speech sounds and plays a role in reading. The visuospatial sketchpad is used in the creation of mental images and in the solution of visual and spatial problems. The central executive is a controlling attentional system that supervises and coordinates current cognitive processing.

Formal models of memory. A number of formal models of memory that can be run as computer simulations have been developed. Among the most influential of these are Jerome Raaijmaker's and Richard Shiffrin's 1981 SAM model, James McClelland, David Rumelhart, and Geoffrey Hinton's 1986 PDP model, and John Anderson's 1993 ACT model.

SAM (Search of Associative Memory) is a mathematical model based upon items and the strength of associations between them. It is particularly appropriate to the learning of lists of words. Each word has a memory strength as a result of it being studied, and each word has an associate strength with the other words in the studied list. The memory strength is combined with the association between the word and the context in which it was learned to produce a strength that is the basis of recognition or retrieval. The model can account for many of the memory phenomena associated with the learning of lists, but it shares with the other two formal models described here the difficulty that many of its assumptions are not based on observations and are difficult to test.

The PDP (Parallel Distributed Processing) model is a neural network model inspired by the analogy of neural circuits in the brain. The network consists of units that are connected to form a network. The strengths of the connections (weights) are adjusted as the network is trained to produce correct responses. Activation spreads through the network and the weightings direct that spread. A response is selected when it achieves a sufficient level of activation. One feature of neural network models is that memory is not located in one place but is captured by particular patterns of activation over many units and links. The neural network models are attractive in apparently simulating the structure of the brain. The choice of the particular structure of units and their interconnections, however, turns out to be important for each simulation of human memory. A general representation that is applicable to many types of remembering has yet to be developed.

The ACT framework is a production system theory for both memory of facts and skills. Anderson has developed several versions of ACT including ACT-R (Adaptive Control of Thought-Rational). Production rules are condition-action rules of the form: If this is the condition, then execute that action. Within the system, units of information are linked by associations, with the association strength being increased through use. The ACT models were developed to account for problem solving and skill acquisition as well as memory. As with the other formal models discussed here, there are many assumptions that make a model difficult to evaluate.

Memory Functions

What is remembered of a particular event depends upon the way in which it is processed. Elaborate processing that emphasizes meaning and associations that are familiar leads to good recall. So, for example, the word albatross would be remembered poorly if only the font in which it was printed was noticed and little thought was given to its meaning. It is much more likely to be remembered, however, if at the time the word is read the reader thinks about how albatrosses are white seabirds living in southern oceans. On the other hand, if what is encountered is difficult to understand, then not only will it be poorly remembered but what is remembered may be distorted by an effort to comprehend the meaning.

The processing of new information draws very heavily upon memory of past experience. Schemas have been developed for often-encountered familiar situations such as going to a supermarket or eating at a restaurant. These schemas guide understanding and memory of the new events but may also lead to memory errors by adding expected events that did not actually occur. Information that is organized on the basis of one's existing knowledge is much easier to learn and remember than is disorganized information. So, for example, a list of the names of animals is much easier to memorize if it is categorized according to type of animals (domestic, farm, wild) and if the categories are laid out in a structured way. Experts in an area memorize new information within their area of expertise much more quickly than do novices. So, soccer fans easily learn new soccer scores and chess masters memorize real board configurations easily.

When material is restudied to strengthen the memory of it, the shorter the interval between the first and second study periods, the less the improvement in recall. This spacing effect is large, so that studying in two spaced sessions can produce twice as much recall as a single session of equal length. The rereading of factual material makes only a small contribution to the further learning of it. Testing oneself by retrieving studied material, however, is a particularly effective technique for improving memory.

What is remembered depends upon the information that is available to cue recall when it is retrieved. In 1983 Tulving summarized much research in the encoding specificity principle. This principle asserts that retrieval is successful to the extent that the cues available at retrieval match those that were processed by the learner at the study phase. The retrieval cues may be aspects of the material that was studied, but they also include environmental cues and the mood and mental state of the learner.

The learning of information that is similar creates a problem for retrieval. There is interference from similar material learned earlier (proactive interference) and from material encountered since the original learning (retroactive interference), and these reduce recall. More insidious are misinformation effects. These occur when misleading information is presented, for example, to eyewitnesses during questioning. The misleading information is then frequently recalled, and the original information becomes very difficult to retrieve.

When tested across time, forgetting follows a logarithmic curve–information loss is rapid initially but then information is lost more slowly. Nevertheless, the fate of information that has been initially very well learned is rather different. Where facts, names, or foreign-language vocabulary have been used repeatedly but are no longer regularly recalled, the pattern of their forgetting is an initial loss over a three-year period, after which recall may be equally good with delays of one or twenty-five years.

See also: Memory, subentry on Myths, Mysteries, and Realities.

bibliography

Anderson, John R. 1993. Rules of the Mind. Hillsdale, NJ: Erlbaum.

Baddeley, Alan D. 1997. Human Memory: Theory and Practice. Hove, Eng.: Psychology Press.

Bahrick, Harry P. 1984. "Semantic Memory Content in Permastore: Fifty Years of Memory for Spanish Learned in School." Journal of Experimental Psychology: General 113:1–29.

Bartlett, Frederick C. 1932. Remembering. Cambridge, Eng.: Cambridge University Press.

Bower, Gorden H.; Black, John B.; and Turner, Terrence J. 1979. "Scripts in Memory for Text." Cognitive Psychology 11:177–220.

Bower, Gorden H.; Clark, Mical C.; Lesgold, Alan M.; and Winzenz, David. 1969. "Hierarchical Retrieval Schemes in Recall of Categorised Word Lists." Journal of Verbal Learning and Verbal Behavior 8:323–343.

Bransford, John D., and Johnson, Marcia K. 1972. "Contextual Prerequisites for Understanding: Some Investigations of Comprehension and Recall." Journal of Verbal Learning and Verbal Behavior 11:717–726.

Carrier, Mark, and Pashler, Harold. 1992. "The Influence of Retrieval on Retention." Memory and Cognition 20:633–642.

Chase, William G., and Simon, Herbert A. 1973. "The Mind's Eye in Chess." In Visual Information Processing, ed. William G. Chase. New York: Academic Press.

Conway, Martin A. 1996. "Autobiographical Memory." In Memory, ed. Elizabeth L. Bjork and Robert A. Bjork. San Diego, CA: Academic Press.

Craik, Fergus I. M., and Tulving, Endel. 1975. "Depth of Processing and the Retention of Words in Episodic Memory." Journal of Experimental Psychology: General 104:268–294.

Dempster, Frank N. 1996. "Distributing and Managing the Conditions of Encoding and Practice." In Memory, ed. Elizabeth L. Bjork and Robert A. Bjork. San Diego, CA: Academic Press.

Eich, Eric, and Metcalfe, Janet. 1989. "Mood Dependent Memory for Internal versus External Events." Journal of Experimental Psychology: Learning, Memory, and Cognition 15:443–455.

Fritz, Catherine O.; Morris, Peter E.; Bjork, Robert A.; Gelman, Rochel; and Wickens, Thomas D. 2000. "When Further Learning Fails: Stability and Change following Repeated Presentation of Text." British Journal of Psychology 91:493–511.

Haberlandt, Karl. 1999. Human Memory: Explorations and Application. Boston: Allyn and Bacon.

Jacoby, Larry L. 1983. "Remembering the Data: Analyzing Interactive Processes in Reading." Journal of Verbal Learning and Verbal Behavior 22:485–508.

Koriat, Asher, and Goldsmith, Morris. 1996. "Memory Metaphors and the Real Life/Laboratory Controversy: Correspondence versus Storehouse Conceptions of Memory." Behavioural and Brain Sciences 19:167–228.

Loftus, Elizabeth F., and Loftus, Geoffrey R. 1980. "On the Permanence of Stored Information in the Human Brain." American Psychologist 35:585–589.

McClelland, James L.; Rumelhart, David E.; and Hinton, Geoffrey E. 1986. "The Appeal of Parallel Distributed Processing." In Parallel Distributed Processing: Explorations in the Microstructure of Cognition, ed. David E. Rumelhart, James L. McClelland, and the PDP Group. Cambridge, MA: MIT Press.

Morris, Peter E.; Tweedy, Margaret; and Gruneberg, Michael M. 1985. "Interest, Knowledge, and the Memorising of Soccer Scores." British Journal of Psychology 76:415–425.

Raaijmakers, Jerome G., and Shiffrin, Richard M. 1981. "SAM: Search of Associative Memory." Psychological Review 88:93–134.

Roediger, HenryL., III, and McDermott, Kathleen B. 1999. "Distortions of Memory." In The Oxford Handbook of Memory, ed. Endel Tulving and Fergus I. M. Craik. Oxford: Oxford University Press.

Roediger, HenryL., iii; Weldon, Mary S.; and Challis, Bradford H. 1989. "Explaining Associations between Implicit and Explicit Measures of Retention: A Processing Account." In Varieties of Memory and Consciousness: Essays in Honour of Endel Tulving, ed. Henry L. Roediger and Fergus I. M. Craik. Hillsdale, NJ: Erlbaum.

Rubin, David C., and Wenzel, Amy E. 1996. "100 Years of Forgetting: A Quantitative Description of Retention." Psychological Review 103:734–760.

Tulving, Endel. 1983. Elements of Episodic Memory. Oxford, Eng.: Oxford University Press.

Tulving, Endel, and Schacter, Daniel L. 1990. "Priming and Human Memory Systems." Science 247:301–306.

Peter E. Morris