EXPERTS' MEMORIES

An expert is "one who has acquired special skill in or knowledge about a particular subject through professional training and practical experience" (Webster's, 1976, p. 800). By that definition, experts will have a greater body of knowledge about their domain of expertise than other individuals. More remarkable is the experts' accurate memory for new experiences in their domain. Some athletes can discuss minute details of individual plays from games played years ago. Expert chess players can readily recall chess positions from their matches in recent tournaments.

Early in the twentieth century many believed that experts were innately gifted with a superior memory. Numerous anecdotes attested to such amazing powers of recollection. For example, Mozart was supposed to be able to reproduce a presented piece of music after hearing it a single time. Later research, however, cast doubt on the hypothesis of superior innate memory in experts and has demonstrated that experts' remarkable recall is limited to their specialties and arises from acquired skills and knowledge.

The Specificity of Experts' Superior Memory

The most influential research on experts' memories focused initially on chess masters' superior recall of board positions (Chase and Simon, 1973). Chess players ranging from beginners to international masters were shown a position from an actual chess game (such as the one illustrated in panel A of Figure 1) for a brief time (normally five seconds) and then asked to recall the location of all the chess pieces. The ability to recall increased as a function of chess skill. Beginners at chess were able to recall the correct location of about four pieces, whereas international-level players recalled nearly all of the more than twenty pieces.

To rule out the innateness of the chess masters' superior visual memory, Chase and Simon had chess players recall chessboards with randomly placed pieces (as illustrated in Panel B of Figure 1). With briefly presented random chessboards, players at all levels of skill had roughly the same poor recall performance and were able to recall the correct location of only three to five pieces on the average—a performance comparable to that of chess beginners for actual positions from chess games. Further, Chase and Simon showed that when an actual chess position was shown using an unfamiliar notation (see Panel C in Figure 1), the chess expert was able to display a similar level of superior memory performance after a brief period of adjustment. This result implies that the superior memory of experts is not innate but rather a function of learned skills. Since Chase and Simon's classic study, other investigators have arrived at similar findings for experts in other fields such as computer programming, basketball, and dance (Ericsson, Patel, and Kintsch, 2000).

The Role of Meaningful Relations in Superior Memory Performance

Without the expertise of a master, it is nearly impossible to grasp the meaningful relations between chess pieces perceived by the expert in panels A and C of Figure 1. If, on the other hand, the availability of knowledge providing meaning to a stimulus is critical to superior memory, it should be possible to demonstrate the same effect in a domain where all adults are proficient, such as language. Human adults are able to recall verbatim meaningful sentences of twenty or more words after a brief presentation (Chase and Ericsson, 1982). An example of such a sentence would be, "The woman in front of him was eating peanuts that smelled so good that he could barely contain his hunger." If the words of the sentence are randomly rearranged in a manner analogous to that used in Chase and Simon's procedure for generating random chessboards, accurate verbatim recall drops to around six words. An example of a random rearrangement of the above sentence would be, "Was smelled front that that his the peanuts he good hunger eating barely woman of so in could that him contain."

For random lists of words, the recall of subjects is limited by the small number of words they can keep rehearsing, and once they stop rehearsal, the words are quickly forgotten. In contrast, once meaningful sentences are understood, their meaning is well retained in long-term memory. For example, during normal comprehension of a text, the essential information in each sentence is efficiently stored in memory so it can be integrated with related information presented later in the text (Ericsson and Kintsch, 1995).

Stimuli from an unfamiliar domain of expertise, such as diagrams of chess positions and medical terms, are about as meaningless to most adults as random lists of words and digits. Recent studies have shown that memory for meaningless information can be dramatically improved through training by actively seeking out meaningful associations for the meaningless material. For example, the sequence 671945 can be remembered as 67 being the retirement age and 1945 being the year of the end of World War II. Through extended training individuals can acquire memory skills allowing them to increase their memory of briefly presented lists of numbers from an initial level of seven digits to over eighty random digits. Hence, it is possible for regular college students to attain exceptional memory performance after 50 to 200 hours of practice. Laboratory studies of individuals with exceptional memory performance for numbers, names, and pictures reveal that they rely on acquired memory skills that often involve some kind of mnemonics (Ericsson and Lehmann, 1996; Wilding and Valentine, 1997).

How Superior Memory of Experts Mediates Their Superior Performance on Representative Tasks

The primary goal for all experts is to excel at the demands of their fields. For example, chess experts need to find the best moves to win chess matches, and medical experts have to diagnose sick patients in order to give them the best treatment. Unlike the memory experts who attempt to improve their memory performance by acquiring mnemonic techniques through extended practice, chess experts and medical doctors do not deliberately train their memory. Their superior memory ability must thus be a byproduct of their improved performance on representative tasks (Vicente and Wang, 1988). Furthermore, experts appear to store task-relevant information in memory when they normally perform representative tasks in their domain, because, if they are unexpectedly asked to recall information about a performed task, their memory is typically far superior to that of less skilled individuals.

In fact, experts' incidental memory of the relevant information is frequently so good that instructing them to intentionally memorize the information does not reliably improve their memory. For example, when chess experts analyze a position to find the best move, their memory of the position is just as good whether they were informed about an upcoming memory test or not. As part of performing the representative task of selecting the best move, the experts encode the important features of the presented information and store them in an accessible form in memory. In contrast, when subjects, after training based on mnemonics and knowledge unrelated to chess, attain a recall performance comparable with that of the chess experts, they still lack the ability to extract the information important for selecting the best move. Hence, the remarkable characteristic of expert memory is not just the amount recalled, which can often be matched by training, but the rapid extraction and storage of important patterns and relevant information that allows superior execution of the representative task (Ericsson, Patel, and Kintsch, 2000).

An analysis of expert performance shows that it is not sufficient to have merely stored the knowledge in memory; it is also critical that the relevant knowledge be well organized and easily retrievable. In fact, the principal challenge of expertise is to acquire and organize the vast body of domain knowledge (Chi, Feltovich, and Glaser, 1981) such that all relevant prior knowledge can be immediately accessed to guide action in encountered situations. For example, with his or her superior organization of knowledge, a chess expert can rapidly perceive a promising move, or a medical expert can rapidly notice an inconsistency in a suggested diagnosis.

Efficient and reliable storage of relevant information in memory is especially important to experts when they engage in planning and complex reasoning that mediate their superior performance. During planning experts have to mentally compare many alternative sequences of actions, storing a great deal of information in working memory. Consequently, beginning chess players do not generate long plans, and it takes years of chess study before chess experts are able to plan long sequences of future moves reliably (Charness, 1989). Chess masters eventually improve their memory skills for planning so much that they are even able to play chess without seeing the chessboard (blindfold chess). Analyses of the superior ability to plan suggest that experts acquire memory skills that allow them to rely on long-term memory for storage of generated information (Ericsson and Kintsch, 1995). Research on expertise is making it increasingly clear that the vast knowledge of experts has to be well organized and supplemented with special memory skills so as to support memory-demanding planning, design, and reasoning.

Further research has revealed the complex and intricate structure of expert performance and its associated memory skills. These skills are not attained automatically with experience but require engagement in deliberate practice that is often designed by teachers. Even the most talented individuals have spent around ten years of intense preparation before attaining a world-class level of performance in many domains such as sports, chess, and arts (Ericsson, 1996).

See also:NATURAL SETTINGS, MEMORY IN

Bibliography

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K. AndersEricsson