The theoretical framework presented in this article explains expert performance as the end result of individuals' prolonged efforts to improve performance while negotiating motivational and external constraints. In most domains of expertise, individuals begin in their childhood a regimen of effortful activities (deliberate practice) designed to optimize improvement. Individual differences, even among elite performers, are closely related to assessed amounts of deliberate practice. Many characteristics once believed to reflect innate talent are actually the result of intense practice extended for a minimum of 10 years. Analysis of expert performance provides unique evidence on the potential and limits of extreme environmental adaptation and learning.Our civilization has always recognized exceptional individuals, whose performance in sports, the arts, and science is vastly superior to that of the rest of the population. Speculations on the causes of these individuals' extraordinary abilities and performance are as old as the first records of their achievements. Early accounts commonly attribute these individuals' outstanding performance to divine intervention, such as the influence of the stars or organs in their bodies, or to special gifts (Murray, 1989). As science progressed, these explanations became less acceptable. Contemporary accounts assert that the characteristics responsible for exceptional performance are innate and are genetically transmitted.The simplicity of these accounts is attractive, but more is needed. A truly scientific account of exceptional performance must completely describe both the development leading to exceptional performance and the genetic and acquired characteristics that mediate it. This account must specify the critical differences between exceptional and ordinary performers. It must also show that any postulated genetic differences can be hereditary and are plausible from an evolutionary perspective. Theoreticians in behavioral genetics (Plomin, DeFries, & McClearn, 1990) We thank Peter Usinger and Stefanie Heizmann for their help in the data collection and Catherine Ashworth, Gregory Carey, Robert Crutcher, Janet Grassia, Reid Hastie, Stefanie Heizmann, Charles Judd, Ronald Kellogg, Robert Levin, Clayton Lewis, William Oliver, Peter Poison, Robert Rehder, Kurt Schlesinger, Vivian Schneider, and James Wilson for their valuable comments on earlier drafts of this article. Helpful suggestions and valuable criticism by Richard Shiffrin on previously submitted versions of this article are gratefully acknowledged.Correspondence concerning this article should be sent to K. Anders Ericsson, who is now at the Department of Psychology R-54, Florida State University, Tallahassee, Florida 32306-1051. because observed behavior is the result of interactions between environmental factors and genes during the extended period of development. Therefore, to better understand expert and exceptional performance, we must require that the account specify the different environmental factors that cou...

To account for the large demands on working memory during text comprehension and expert performance, the traditional models of working memory involving temporary storage must be extended to include working memory based on storage in long-term memory. In the proposed theoretical framework cognitive processes are viewed as a sequence of stable states representing end products of processing. In skilled activities, acquired memory skills allow these end products to be stored in long-term memory and kept directly accessible by means of retrieval cues in short-term memory, as proposed by skilled memory theory. These theoretical claims are supported by a review of evidence on memory in text comprehension and expert performance in such domains as mental calculation, medical diagnosis, and chess.

The central proposal of this article is that verbal reports are data. Accounting for verbal reports, as for other kinds of data, requires explication of the mechanisms by which the reports are generated, and the ways in which they are sensitive to experimental factors (instructions, tasks, etc.). Within the theoretical framework of human information processing, we discuss different types of processes underlying verbalization and present a model of how subjects, in response to an instruction to think aloud, verbalize information that they are attending to in short-term memory (STM). Verbalizing information is shown to affect cognitive processes only if the instructions require verbalization of information that would not otherwise be attended to. From an analysis of what would be in STM at the time of report, the model predicts what can reliably be reported. The inaccurate reports found by other research are shown to result from requesting information that was never directly heeded, thus forcing subjects to infer rather than remember their mental processes. After a long period of time during which stimulus-response relations were at the focus of attention, research in psychology is now seeking to understand in detail the mechanisms and internal structure of cognitive processes that produce these relations. In the limiting case, we would like to have process models so explicit that they could actually produce the predicted behavior from the information in the stimulus.

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Expert and exceptional performance are shown to be mediated by cognitive and perceptual-motor skills and by domain-specific physiological and anatomical adaptations. The highest levels of human performance in different domains can only be attained after around ten years of extended, daily amounts of deliberate practice activities. Laboratory analyses of expert performance in many domains such as chess, medicine, auditing, computer programming, bridge, physics, sports, typing, juggling, dance, and music reveal maximal adaptations of experts to domain-specific constraints. For example, acquired anticipatory skills circumvent general limits on reaction time, and distinctive memory skills allow a domain-specific expansion of working memory capacity to support planning, reasoning, and evaluation. Many of the mechanisms of superior expert performance serve the dual purpose of mediating experts' current performance and of allowing continued improvement of this performance in response to informative feedback during practice activities.

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Counter to the common belief that expert performance reflects innate abilities and capacities, recent research in different domains of expertise has shown that expert performance is predominantly mediated by acquired complex skills and physiological adaptations. For elite performers, supervised practice starts at very young ages and is maintained at high daily levels for more than a decade. The effects of extended deliberate practice are more far-reaching than is commonly believed. Performers can acquire skills that circumvent basic limits on working memory capacity and sequential processing. Deliberate practice can also lead to anatomical changes resulting from adaptations to intense physical activity. The study of expert performance has important implications for our understanding of the structure and limits of human adaptation and optimal learning. In nearly every field of human endeavor, the performance of the best practitioners is so outstanding, so superior even to the performance of other highly experienced individuals in the field, that most people believe a unique, qualitative attribute, commonly called innate talent, must be invoked to account for this highest level of performance. Although these differences in performance are by far the largest psychologists have been able to reliably measure among healthy adults, exceptional performance has not, until recently, been extensively studied by scientists. In the last decade, interest in outstanding and exceptional achievements and performance has increased dramatically. Many books have been recently published on the topic of genius (for example,

Traditionally, professional expertise has been judged by length of experience, reputation, and perceived mastery of knowledge and skill. Unfortunately, recent research demonstrates only a weak relationship between these indicators of expertise and actual, observed performance. In fact, observed performance does not necessarily correlate with greater professional experience. Expert performance can, however, be traced to active engagement in deliberate practice (DP), where training (often designed and arranged by their teachers and coaches) is focused on improving particular tasks. DP also involves the provision of immediate feedback, time for problem-solving and evaluation, and opportunities for repeated performance to refine behavior. In this article, we draw upon the principles of DP established in other domains, such as chess, music, typing, and sports to provide insight into developing expert performance in medicine.ACADEMIC EMERGENCY MEDICINE 2008; 15:988-994 ª