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 could selectively promote and facilitate the achievement of such performance. In addition, recent research on expert performance and expertise (Chi, Glaser, & Farr, 1988; Ericsson & Smith, 199la) has shown that important characteristics of experts' superior performance are acquired through experience and that the effect of practice on performance is larger than earlier believed possible. For this reason, an account of exceptional performance must specify the environmental circumstances, such as the duration and structure of activities, and necessary minimal biological attributes that lead to the acquisition of such characteristics and a corresponding level of performance. An account that explains how a majority of individuals can attain a given level of expert performance might seem inherently unable to explain the exceptional performance of only a small number of individuals. However, if such an empirical account could be empirically supported, then the extreme characteristics of experts could be viewed as having been acquired through learning and adaptation, and studies of expert performance could provide unique insights into the possibilities and limits of change in cognitive capacities and bodily functions. In this article we propose a theoretical framework that explains expert performance in terms of acquired characteristics resulting from extended deliberate practice and that limits the role of innate (inherited) characteristics to general levels of activity and emotionality. We provide empirical support from two new studies and from already published evidence on expert performance in many different domains. Sir Francis Gallon was the first scientist to investigate the possibility that excellence in diverse fields and domains has a common set of causes. He found that eminent individuals in the British Isles were more likely to have close relatives who were also eminent-although not necessarily in the same domain-than to have distant relatives who were eminent. He concluded that eminence, that is, exceptional performance in a 363 364 K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER field, must be transmitted from parents to their offspring. Galton (1869Galton ( /1979 argued that eminence was a virtually inevitable consequence of inherited "natural ability," which was the conjunction of three types of elements: By natural ability, I mean those qualities of intellect and disposition, which urge and qualify a man to perform acts that lead to reputation. I do not mean capacity without zeal, nor zeal without capacity, nor even a combination of both of them, without an adequate power of doing a great deal of very laborious work. (p. 37) If a man is gifted with vast intellectual ability, eagerness to work, and power of working, I cannot comprehend how such a man should be repressed, (p. 39) Gallon readily acknowledged the importance of physiological exercises for improvement in motor performance and drew a direct analogy to improvement of mental powers through studying and education. In his view, hereditary factors determine the limit of the attainable performance for a given individual: So long as he is a novice, he perhaps flatters himself there is hardly an assignable limit to the education of his muscles; but the daily gain is soon discovered to diminish, and at last it vanishes altogether. His maximum performance becomes a rigidly determinate quantity. (Gallon, 1869 (Gallon, /1979 Even a hundred years later, Gallon's conceptualization of eminenl performance as reflecting a higher level of ultimate performance determined primarily by innale capacilies (lalenl) is slill the modal view among people outside genetics and behavioral genetics. Genelic influences are still incorreclly viewed as delerminislic factors that lead to unmodifiable consequences determining the structure of the human body and its nervous system (Plomin, 1991). Gallon's recognition of the interaclion belween environmenlal and genelic faclors is clearly shown in his iri-parl definition of nalural abilily as innale capacily, zeal, and power to do very laborious work. The lasl Iwo factors are also likely to have a genetic component as we argue later in this article. Nonetheless, the study of eminent performance subsequenl to Gallon has given far less emphasis to zeal and power to do very laborious work and has focused primarily on genelic influences on slruclure and capacilies. Everyone agrees lhal ihe shared characlerislics of Ihe human body and ils nervous system are due lo shared genes. Similarly, Ihe successful idenlificalion of genelic factors influencing individual differences in heighl and other physical characterislics has inspired researchers to search for genetic mechanisms regulaling individual differences in mental capacities. Hence the focus of research on lalenl has been on finding similar basic structural differences in the nervous system lhat might mediate stable differences in expert performance. If genetic factors rigidly determine maximal performance, il is reasonable lo assume that these genetic factors cannol be influenced by praclice and iraining and hence remain slable across lime. Early genelic research showed that many physical and anatomical attributes, such as heighl and facial fealures, are largely determined by hereditary factors. In many sports the height of elite athletes is systemalically differenl from lhal of ihe normal populalion. Greater height is an obvious advantage in basketball, high jumping, and most sports emphasizing strength. Shorter height is an advantage in gymnastics. Differences in height were found to discriminate well among male athletes of different events at the Olympic games in Montreal, although the average height of all athletes did not differ from that of a control group of studenls (Carter, Ross, Aubrey, Hebbelinck, & Borms, 1982) . Elite alhletes also differ in the size of their muscles, such as arm girth, and in the amount offal measured by skin folds. Endurance alhletes have a much higher aerobic abilily, larger hearls, more capillaries supplying blood lo muscles, and a higher percentage of slow-twilch muscle fibers (Ericsson, 1990) . Unlil quite recently researchers commonly believed thai percenlages of muscle fiber types and aerobic power "are more than 90% determined by heredity for males and females" (Brown & Mahoney, 1984, p. 609). Some researchers have therefore reasoned by analogy that basic general characteristics of the nervous system, such as speed of neural transmission and memory capacities, have a genelic origin and cannot be changed through training and practice. Early efforts to find stable individual differences in neural transmission speed with simple response time (RT) and olher basic capacilies were remarkably unsuccessful (Guilford, 1967) . Binel (Varon, 1935) slarted oul using tests of basic perceptual and cognitive capacities to measure IQ, but found large practice effects, which were later documented by Gibson (1969) . Binet eventually developed successful IQ tests derived from tests measuring comprehension, knowledge, and acquired skills. Because IQ reflects both environmental and genetic factors, recent research has challenged its interprelation and relation to successful performance outside the school environmenl (Ceci, 1990; Howe, 1990) . The relaiion of IQ to exceptional performance is rather weak in many domains, including music (Shuter-Dyson, 1982 ) and chess (Doll & Mayr, 1987) . For scientists, engineers, and medical doctors that complete the required educalion and training, the correlations between ability measures and occupational success are only around 0.2, accounting for only 4% of the variance (Baird, 1985) . More generally, prediction ofoccupational success from psychometric tests has not been very successful (Tyler, 1965) . In a review of more than one hundred studies, Ghiselli (1966) found ihe average correlation between success-on-the-job measuring and aptilude-tesl scores to be 0.19. Aptitude tesls can predict performance immediately after Iraining with an average correlation of 0.3, bul Ihe correlation between performance after training and final performance on the job is only about 0.2 (Ghiselli, 1966). Reviews of subsequent research (Baird, 1985; Linn, 1982) have reported very similar correlation estimates. When corrections were made for the restriclion of range of these samples and for unreliability of performance measures, Hunter and Hunter (1984) found that only cognitive ability emerged as a useful predictor with an average adjusted correlalion of 0.5 with early job performance. However, a recent review (Hulin, Henry, & Noon, 1990 ) has shown thai with increased experience on the job the predictive validities of ability tests for performance decrease over time by an average correlation of 0.6 (after correclions for reslrictions of range and unreliability of performance measures). This implies thai ability tesls can predict early performance on a job, whereas final performance is poorly predicted. Even fora well-THE ROLE OF DELIBERATE PRACTICE 365 defined skill, such as typing, with relatively unselect groups of subjects, numerous efforts to predict the attained performance from pretraining aptitude tests have failed (Clem, 1955) . Striking differences between eminent individuals (experts) and less accomplished individuals are found, not surprisingly, when their current performance in the field of expertise is compared (Ericsson & Smith, 1991 b); experts are faster and more accurate than less accomplished individuals. However, experts' superior speed in their domain of expertise does not transfer to general tests of speed, such as simple RT, or to general tests of perception (Starkes, 1987; Starkes & Deakin, 1984) . Similarly, experts' memory for representative stimuli from their domain is vastly superior to that of lesser experts, especially for briefly presented stimuli. But when tested on randomly rearranged versions of representative stimuli from their domain presented with short exposures or on materials outside their domain, the memory of experts is no better than that of ordinary individuals. The domain-specific nature of experts' superior performance implies that acquired knowledge and skill are important to attainment of expert performance. We can cite only two abilities that investigators have argued directly reflect genetic factors. Some successful musicians can recognize a musical note in isolation by its pitch (perfect pitch). Championship-level typists can tap their fingers faster than normal (Book, 1924; Keele & Hawkins, 1982) . Although we claim that genetic factors have little direct impact on ultimate adult performance, a plausible role for hereditary factors is in the developmental history of an individual. Superior performance by very young children without prior instruction may suggest exceptional promise, leading to the early onset of training. This in turn leads to a consistently greater accumulation of practice (and hence, by our framework, performance) relative to later-starting individuals. In the General Discussion section we consider this potential indirect role of innate talent at length, concluding instead that unique environmental conditions and parental support, rather than talent, may be the important factors determining the initial onset of training and ultimate performance. In summary, the search for stable heritable characteristics that could predict or at least account for the superior performance of eminent individuals has been surprisingly unsuccessful. The best evidence for the effect of heritable characteristics comes from several types of sports, for which anatomical characteristics such as height systematically differ for elite performers compared with the average population. The belief that the striking differences between expert performers and less accomplished performers reflect innate abilities (talent) is so strong that the failure to identify the specific talents necessary for expert performance in a given domain is viewed, at most, as a temporary problem until the relevant talents are discovered. The conviction in the importance of talent appears to be based on the insufficiency of alternative hypotheses to explain the exceptional nature of expert performance. If one agrees with Gallon's plausible claim that the improvements resulting from experience and practice occur during limited time until a stable maximal level of performance is attained, the factors limiting further improvement must be fixed and unmodifiable by environmental factors. The most likely source of such unmodifiable factors is genetic. However, this argument is only valid if the associated assumptions can be verified empirically. In the following two sections we examine the assumption that with extensive experience in a domain a maximal level of performance is automatically reached and that the period of improvement has a relatively limited duration, especially for talented individuals. Maximal Performance? The view that merely engaging in a sufficient amount of practice, regardless of the structure of that practice, leads to maximal performance has a long and contested history. In their classic studies of Morse Code operators, Bryan and Harter (1897, 1899) identified plateaus in skill acquisition, when for long periods subjects seemed unable to attain further improvements. However, with extended efforts, subjects could restructure their skill to overcome plateaus. Keller (1958) later showed that these plateaus in Morse Code reception were not an inevitable characteristic of skill acquisition, but could be avoided by different and better training methods. Nonetheless, Harter (1897, 1899) had clearly shown that with mere repetition, improvement of performance was often arrested at less than maximal levels, and further improvement required effortful reorganization of the skill. Even very experienced Morse Code operators could be encouraged to dramatically increase their performance through deliberate efforts when further improvements were required for promotions and external rewards (Bryan & Harter, 1897) . More generally, Thorndike (1921) observed that adults perform at a level far from their maximal level even for tasks they frequently carry out. For instance, adults tend to write more slowly and illegibly than they are capable of doing. Likewise, adults (including clerks with many years of frequent daily experience) add numbers far more slowly than they can when they are doing their best. Thorndike (1921, p. 178) accounts for these curious observations with the following comment: "It is that we have too many other improvements to make, or do not know how to direct our practice, or do not really care enough about improving, or some mixture of these three conditions." In support of this claim, he reported several laboratory studies and a study of experienced typesetters by Aschaffenburg (1896), which showed gradual improvements of up to 25% as a result of continued testing. Kitson (as described in Book & Norvell, 1922) found that during a 20-week period, typesetters with around 10 years of experience gradually improved their job performance between 58% and 97% in response to a bonus system rewarding higher performance. Dvorak, Merrick, Dealey, and Ford (1936) reported substantial improvements in experienced typists as a result of deliberate efforts. Because performance in sports, especially, has been measured under standardized conditions, and the best performance has been recorded at world, national, district, and club levels, it can be clearly demonstrated that performance has continually improved during this entire century. Schulz and Curnow (1988) found that throughout the history of the Olympic Games, the best performance for all events has improved-in some cases by more than 50%. It is generally recognized that 366 K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER some of these improvements are due to equipment and rule changes, but improvements are great even in events with minor changes, such as running and swimming. Increases in duration, intensity, and structure of training appear to play a major role. The fastest time for the marathon in the 1896 Olympic Games was just a minute faster than the required entry time in large marathon races such as the Boston Marathon (Ericsson, 1990) . The fastest rate of typing in the World Championship in typing increased from 82 words per minute in 1904 to 147 words per minute in 1923-an improvement of 80% (Book, 1925a) . Even in music there is evidence for improved skill. When Tchaikovsky asked two of the greatest violinists of his day to play his violin concerto, they refused, deeming the score unplayable (Platt, 1966). Today, elite violinists consider this concerto part of the standard repertory. The improvement in music training is so great that according to Roth (1982) the violin virtuoso Paganini "would indeed cut a sorry figure if placed upon the modern concert stage" (p. 23). In virtually all domains, insights and knowledge are steadily accumulating and the criteria for eminent as well as expert performance undergo continuous change. To reach the status of an expert in a domain it is sufficient to master the existing knowledge and techniques. To make an eminent achievement one must first achieve the level of an expert and then in addition surpass the achievements of already recognized eminent people and make innovative contributions to the domain. In sum, the belief that a sufficient amount of experience or practice leads to maximal performance appears incorrect. There is a relatively widespread conception that if individuals are innately talented, they can easily and rapidly achieve an exceptional level of performance once they have acquired basic skills and knowledge. Biographical material disproves this notion. In their classic study of expertise in chess, Simon and Chase (1973) observed that nobody had attained the level of an international chess master (grandmaster) "with less than about a decade's intense preparation with the game" (p. 402). Simon and Chase estimated that the amount of knowledge a chess master has acquired is comparable in size to the vocabulary of an adult native speaker of English. It takes normal individuals approximately a decade to acquire this vocabulary. Similarly, Krogius (1976) showed that the time between chess players' first learning the rules of chess and attaining international chess master status was 11.7 years for those who learned chess rules late (after age 11) and even longer for those who started early, that is, 16.5 years. If only well-established domains with a large number of active individuals are considered we know of only a small number of exceptions to the general rule that individuals require 10 or more years of preparation to attain international-level performance. The exceptions in this century, such as the famous chess players, Bobby Fischer and Salo Flohr, were only a year shy of the prerequisite 10 years of preparation (Krogius, 1976) . J. R. Hayes (1981) confirmed that 10 years' experience is necessary in another domain, musical composition. He calculated an average of about 20 years from the time individuals started to study music until they first composed an outstanding piece of music. According to Hayes, this long preparation period is necessary because "the composer must know the timbres of the various instruments and the sound, look, and feel of chords and key structures" (p. 209). Most important, Hayes showed that the 10 or more years of necessary experience was not an artifact. Because musicians start very early, insufficient development may restrict their ability to compose before attaining adulthood. Those who started at ages younger than 6 years did not write their first eminent composition until 16.5 years later; those who started between ages 6 and 9 and older than 10 years of age required 22 and 21.5 years, respectively to compose their first distinguished work. Simon and Chase's (1973) "10-year rule" is supported by data from a wide range of domains: music (Sosniak, 1985) , mathematics (Gustin, 1985) , tennis (Monsaas, 1985) , swimming (Kalinowski, 1985) , and long-distance running (Wallingford, 1975) . Long periods of necessary preparation can also be inferred for writers and scientists, although the starting point of their careers is more difficult to determine. Scientists have reported that they made a career decision during their middle or late teens, whereas they most often published a truly major contribution one or two decades later (Lehmann, 1953). Raskin (1936) , who analyzed the 120 most important scientists and 123 most famous poets and authors in the 19th century, found that the average age at which scientists published their first work was 25.2; poets and authors published their first work at the average age of 24.2. Moreover, many years of preparation preceded first publication. The average ages at which the same individuals produced their greatest work were 35.4 for scientists and 34.3 for poets and authors. That is, on average, more than 10 years elapsed between these scientists' and authors' first work and their best work. In many other domains, the highest level of expert performance is displayed by individuals with more than 10 years of experience: evaluation of livestock (Phelps&Shanteau, 1978), diagnosis of X-rays (Lesgold, 1984), and medical diagnosis (Patel & Groen, 1991) . This evidence is consistent with Gallon's (1869/1979) claim that motivation and perseverance are necessary for attainment of eminent performance. Our review has also shown that the maximal level of performance for individuals in a given domain is not attained automatically as function of extended experience, but the level of performance can be increased even by highly experienced individuals as a result of deliberate efforts to improve. Hence, stable levels of performance after extended experience are not rigidly limited by unmodifiable, possibly innate, factors, but can be further increased by deliberate efforts. We have shown that expert performance is acquired slowly over a very long time as a result of practice and that the highest levels of performance and achievement appear to require at least around 10 years of intense prior preparation. However the relation between acquired performance and the amount of practice and experience was found to be weak to moderate in the earlier review. We propose that the reason for this comparatively weak relation is that the current definition of practice is vague. If we are to improve our understanding of the environmental influences mediated through participation in different activities, we must analyze the types of activities commonly called practice. The Role of Deliberate Practice In this section we characterize deliberate practice-those activities that have been found most effective in improving performance. We then contrast deliberate practice with activities that tend to occur more frequently in various domains. Finally, we propose a theoretical framework that explains how expert performance can be attained through deliberate practice. The basic skills required for living in a culture are acquired by virtually all children as part of normal social interaction with a minimum of instruction. In contrast, the skills of reading, writing, and arithmetic have been explicitly taught in schools by teachers with assigned activities of, for example, copying of presented material, for more than 3 thousand years (Eby & Arrowood, 1940) . We want to distinguish activities invented with the primary purpose of attaining and improving skills from other types of everyday activities, in which learning may be an indirect result. On the basis of several thousand years of education, along with more recent laboratory research on learning and skill acquisition, a number of conditions for optimal learning and improvement of performance have been uncovered (Bower & Hilgard, 1981; Gagne, 1970) . The most cited condition concerns the subjects' motivation to attend to the task and exert effort to improve their performance. In addition, the design of the task should take into account the preexisting knowledge of the learners so that the task can be correctly understood after a brief period of instruction. The subjects should receive immediate informative feedback and knowledge of results of their performance. The subjects should repeatedly perform the same or similar tasks. When these conditions are met, practice improves accuracy and speed of performance on cognitive, perceptual, and motor tasks (Fitts & Posner, 1967; Gibson, 1969; Welford, 1968) . Tasks used in laboratory studies of learning that are designed to focus on the accuracy of performance clearly display the relevant cues and the relevant feedback. Studies focusing on speed of performance tend to use easy tasks, where highly accurate performance is rapidly attained, and subjects are instructed to increase the speed of performance while maintaining the high level of accuracy. Under these conditions subjects' performance improves monotonically as a function of the amount of practice according to the power law (J. R. Anderson, 1982; Newell & Rosenbloom, 1981) . In the absence of adequate feedback, efficient learning is impossible and improvement only minimal even for highly motivated subjects. Hence mere repetition of an activity will not automatically lead to improvement in, especially, accuracy of performance (Trowbridge & Cason, 1932) . When laboratory training is extended over longer time periods, studies show that providing a motivated individual with repeated exposure to a task does not ensure that the highest levels of performance will be attained. Assessment of subjects' methods shows that inadequate strategies often account for the lack of improvement. For example, in their study on the effects of practice on digit span, Chase and Ericsson (1981) found a subject who kept rehearsing the digits whose performance showed only minimal improvement. In contrast, all subjects who used preexisting knowledge to encode the presented digits improved dramatically. One subject who discovered how to use efficient retrieval structures increased his performance by over 1000%. Recent reviews of exceptional memory performance (Ericsson, 1985 (Ericsson, ,1988 show that a small set of general methods underlie such performance. After being instructed to use adequate strategies, subjects have attained exceptional levels of memory performance after extended practice (Baltes & Kliegl, 1992; Kliegl, Smith, & Baltes, 1989; . Early investigators of extended skill acquisition in typing (Book, 1925b; Dvorak et al., 1936) and other perceptual-motor skills (Kao, 1937) carefully monitored improvements in performance and collected verbal reports on subjects' cognitive processes. These studies revealed subjects' active search for methods to improve performance and found that changes in methods could often be related to clear improvements. Other studies (Chase & Ericsson, 1981; VanLehn, 1991) have also shown that subjects actively try out different methods and refine methods in response to errors and violated expectations. The critical importance of a correct method or strategy has also been demonstrated in date calculation (Addis & O. A. Parsons, as described in Ericsson & Faivre, 1988) , mental multiplication (Chase & Ericsson, 1982; Staszewski, 1988) , absolute judgment of colors and pitches (for a review see Ericsson & Faivre, 1988) , motor skills (Norman, 1976) , and methods of work (R. H. Seashore, 1939) . The inability of some subjects to discover new methods has sometimes been interpreted as evidence for basic cognitive or perceptual deficits, especially for performance of seemingly simple tasks. However, specific instruction or the generation of new methods can eventually enhance improvement temporarily arrested at suboptimal levels. As the complexity of a desired skill increases beyond the simple structure of most laboratory tasks, the logically possible methods to correctly and incorrectly perform the task by subjects increase as well. To assure effective learning, subjects ideally should be given explicit instructions abojjt the best method and be supervised by a teacher to allow individualized diagnosis of errors, informative feedback, and remedial part training. The instructor has to organize the sequence of appropriate training tasks and monitor improvement to decide when transitions to more complex and challenging tasks are appropriate. Although it is possible to generate curricula and use group instruction, it is generally recognized that individualized supervision by a teacher is superior. Research in education reviewed by Bloom (1984) shows that when students are randomly assigned to instruction by a tutor or to conventional teaching, tutoring yields better performance by two standard deviations-the average tutored student performed at the 98th percentile of students taught with the conventional method. Interestingly, the correlation between prior achievement and achievement on the current course was reduced and corresponded to only about 6% of the variance for the tutored subjects as compared with around 36% for students taught with conventional methods. More generally, improved instruction appears to benefit subjects with lower cognitive ability more than high-ability subjects thus lowering the earlier discussed correlation between cognitive ability and early performance seen under standard training conditions. Most contemporary domains of expertise have evolved over 368 K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER centuries from activities originally centered around playful interaction with learning through active participation. As the levels of performance in the domain increased in skill and complexity, methods to explicitly instruct and train individuals were developed. In all major domains there has been a steady accumulation of knowledge about the best methods to attain a high level of performance and the associated practice activities leading to this performance. Full-time teachers and coaches are available for hire and supervise the personalized training of individuals at different levels of performance starting with beginners. Throughout development toward expert performance, the teachers and coaches instruct the individuals to engage in practice activities that maximize improvement. Given the cost of individualized instruction, the teacher designs practice activities that the individual can engage in between meetings with the teacher. We call these practice activities deliberate practice and distinguish them from other activities, such as playful interaction, paid work, and observation of others, that individuals can pursue in the domain. Consider three general types of activities, namely, work, play, and deliberate practice. Work includes public performance, competitions, services rendered for pay, and other activities directly motivated by external rewards. Play includes activities that have no explicit goal and that are inherently enjoyable. Deliberate practice includes activities that have been specially designed to improve the current level of performance. The goals, costs, and rewards of these three types of activities differ, as does the frequency with which individuals pursue them. Public performance and competitions are constrained in time; these activities as well as rendering a service for pay require that individuals give their best performance at a given time. The distinction between work and training (deliberate practice) is generally recognized. Individuals given a new job are often given some period of apprenticeship or supervised activity during which they are supposed to acquire an acceptable level of reliable performance. Thereafter individuals are expected to give their best performance in work activities and hence individuals rely on previously well-entrenched methods rather than exploring alternative methods with unknown reliability. The costs of mistakes or failures to meet deadlines are generally great, which discourages learning and acquisition of new and possibly better methods during the time of work. For example, highly experienced users of computer software applications are found to use a small set of commands, thus avoiding the learning of a larger set of more efficient commands (see Ashworth, 1992 , for a review). Although work activities offer some opportunities for learning, they are far from optimal. In contrast, deliberate practice would allow for repeated experiences in which the individual can attend to the critical aspects of the situation and incrementally improve her or his performance in response to knowledge of results, feedback, or both from a teacher. Let us briefly illustrate the differences between work and deliberate practice. During a 3-hr baseball game, a batter may get only 5-15 pitches (perhaps one or two relevant to a particular weakness), whereas during optimal practice of the same duration, a batter working with a dedicated pitcher has several hundred batting opportunities, where this weakness can be systematically explored (T. Williams, 1988) . The external rewards of work activities include social recognition and, most important, money in the form of prizes and pay, which enables performers to sustain a living. In play and deliberate practice, external rewards are almost completely lacking. The goal of play is the activity itself, and the inherent enjoyment of it is evident in children who spontaneously play for extended periods of time. Recent analyses of inherent enjoyment in adults reveal an enjoyable state of "flow," in which individuals are completely immersed in an activity (Csikszentmihalyi, 1990) . Similarly, analyses of reported "peak experiences" in sports reveal an enjoyable state of effortless mastery and execution of an activity (Ravizza, 1984) . This state of diffused attention is almost antithetical to focused attention required by deliberate practice to maximize feedback and information about corrective action. In contrast to play, deliberate practice is a highly structured activity, the explicit goal of which is to improve performance. Specific tasks are invented to overcome weaknesses, and performance is carefully monitored to provide cues for ways to improve it further. We claim that deliberate practice requires effort and is not inherently enjoyable. Individuals are motivated to practice because practice improves performance. In addition, engaging in deliberate practice generates no immediate monetary rewards and generates costs associated with access to teachers and training environments. Thus, an understanding of the long-term consequences of deliberate practice is important. We now outline a framework within which we can explain how differential levels of performance are attained as a function of deliberate practice. Our basic assumption-the "monotonic benefits assumption"-is that the amount of time an individual is engaged in deliberate practice activities is monotonically related to that individual's acquired performance. This assumption can be tested empirically. It follows from this assumption that individuals should attempt to maximize the amount of time they spend on deliberate practice to reach expert performance. However, maximization of deliberate practice is neither short-lived nor simple. It extends over a period of at least 10 years and involves optimization within several constraints. First, deliberate practice requires available time and energy for the individual as well as access to teachers, training material, and training facilities (the resource constraint). If the individual is a child or adolescent, someone in the individual's environment must be willing to pay for training material and the time of professional teachers, as well as for transportation to and from training facilities and competitions. Second, engagement in deliberate practice is not inherently motivating. Performers consider it instrumental in achieving further improvements in performance (the motivational constraint). The lack of inherent reward or enjoyment in practice as distinct from the enjoyment of the result (improvement) is con-THE ROLE OF DELIBERATE PRACTICE 369 sistent with the fact that individuals in a domain rarely initiate practice spontaneously. Finally, deliberate practice is an effortful activity that can be sustained only for a limited time each day during extended periods without leading to exhaustion (effort constraint). To maximize gains from long-term practice, individuals must avoid exhaustion and must limit practice to an amount from which they can completely recover on a daily or weekly basis. Considering the cost of pursuing expert-level performance and the small number of individuals who, out of millions of children exposed to such domains as sports and music, can make a living as professionals, it seems remarkable that individuals get started and are encouraged to continue. From many interviews with international-level performers in several domains, Bloom (1985b) found that these individuals start out as children by engaging in playful activities in the domain. After some period of playful and enjoyable experience they reveal "talent" or promise. At this point parents typically suggest the start of instruction by a teacher and limited amounts of deliberate practice. The parents support their children in acquiring regular habits of practice and teach their children about the instrumental value of deliberate practice by noticing improvements in performance. With increased experience and deliberate practice, individuals' performance in the domain reflects an inseparable combination of practice and innate talent. We rely on Bloom's (198 5b) characterization of the period of preparation in three phases, which are illustrated in Figure 1 . The first phase begins with an individual's introduction to activities in the domain and ends with the start of instruction and deliberate practice. The second phase consists of an extended period of preparation and ends with the individual's commitment to pursue activities in the domain on a full-time basis. The third phase consists of full-time commitment to improving performance and ends when the individual either can make a living as a professional performer in the domain or terminates full-time engagement in the activity. During all three phases the individual requires support from external sources, such as parents, teachers, and educational institutions. This framework needs to be extended with a fourth phase to accommodate eminent performance. During this fourth phase the individuals go beyond the knowledge of their teachers to make a unique innovative contribution to their domain. To be complete, our theoretical framework must show how individuals negotiate the various constraints on deliberate practice during that first decade of preparation necessary for attaining international-level performance. There are several methodological problems involved in demonstrating the relevant processes. During the decade or two leading to adult expert performance, many aspects of training and evaluation change. In the beginning, a child's performance is compared with that of other children of the same age in the local neighborhood. At the start of participation in competitions, the reference group consists of other trained individuals of similar ages from a larger area. Success at these earlier stages may eventually lead to participation in competitions at a national and international level. At increased levels of performance, the practice activities obviously change and so do the criteria of evaluation.
Ericsson et al. REF -origin of the meme that 10,000 hours of deliberate practice is needed to achieve expertise-found that attaining expertise required time, materials, teachers, and facilities.
The role of deliberate practice in the acquisition of expert performance
Psychological Review
Computer Science