Fermat's Library | The Role of Deliberate Practice in the Acquisition of Expert Performance annotated/explained version.

Psychological Review

1993, Vol. 100. No. 3, 363-406

OO33-295X/93/S3.OO

The Role of Deliberate Practice in the Acquisition of Expert Performance

K. Anders Ericsson, Ralf Th. Krampe, and Clemens Tesch-Romer

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 individ-

uals, whose performance in sports, the arts, and science is

vastly superior to that of the rest of the population. Specula-

tions on the causes of these individuals' extraordinary abilities

and performance are as old as the first records of their achieve-

ments. 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 in-

nate 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 ex-

ceptional performance and the genetic and acquired character-

istics 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) now argue that this is a very challenging task

K. Anders Ericsson, Institute of Cognitive Science, University of

Colorado at Boulder; Ralf Th. Krampe and Clemens Tesch-Romer,

Max Planck Institute for Human Development and Education, Berlin,

Federal Republic of Germany.

The empirical research for this article was conducted at the Max

Planck Institute for Human Development in Berlin. Research support

by the Max Planck Society and support and encouragement from Paul

Baltes are gratefully acknowledged.

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 acknowl-

edged.

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 ex-

ceptional performance, we must require that the account spec-

ify 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, 1991a) 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 attrib-

utes 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 inher-

ently 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 ac-

quired through learning and adaptation, and studies of expert

performance could provide unique insights into the possibili-

ties 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 charac-

teristics resulting from extended deliberate practice and that

limits the role of innate (inherited) characteristics to general

levels of activity and emotionality. We provide empirical sup-

port from two new studies and from already published evi-

dence on expert performance in many different domains.

Brief Historical Background

Sir Francis Galton 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 do-

main—than to have distant relatives who were eminent. He

concluded that eminence, that is, exceptional performance in a

364

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

field, must be transmitted from parents to their offspring. Gal-

ton (1869/1979) argued that eminence was a virtually inevita-

ble consequence of inherited "natural ability," which was the

conjunction of three types of elements:

By natural ability, I mean those qualities of intellect and disposi-

tion, 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)

Galton readily acknowledged the importance of physiological

exercises for improvement in motor performance and drew a

direct analogy to improvement of mental powers through study-

ing 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 alto-

gether. His maximum performance becomes a rigidly determin-

ate quantity. (Galton, 1869/1979, p. 15)

Even a hundred years later, Galton's conceptualization of emi-

nent performance as reflecting a higher level of ultimate perfor-

mance determined primarily by innate capacities (talent) is still

the modal view among people outside genetics and behavioral

genetics. Genetic influences are still incorrectly viewed as de-

terministic factors that lead to unmodifiable consequences de-

termining the structure of the human body and its nervous

system (Plomin, 1991). Galton's recognition of the interaction

between environmental and genetic factors is clearly shown in

his tri-part definition of natural ability as innate capacity, zeal,

and power to do very laborious work. The last two factors are

also likely to have a genetic component as we argue later in this

article. Nonetheless, the study of eminent performance subse-

quent to Galton has given far less emphasis to zeal and power to

do very laborious work and has focused primarily on genetic

influences on structure and capacities. Everyone agrees that

the shared characteristics of the human body and its nervous

system are due to shared genes. Similarly, the successful identi-

fication of genetic factors influencing individual differences in

height and other physical characteristics has inspired re-

searchers to search for genetic mechanisms regulating individ-

ual differences in mental capacities. Hence the focus of re-

search on talent has been on finding similar basic structural

differences in the nervous system that might mediate stable

differences in expert performance.

Natural Abilities and Other Stable Characteristics

If genetic factors rigidly determine maximal performance, it

is reasonable to assume that these genetic factors cannot be

influenced by practice and training and hence remain stable

across time. Early genetic research showed that many physical

and anatomical attributes, such as height and facial features, are

largely determined by hereditary factors. In many sports the

height of elite athletes is systematically different from that of

the normal population. Greater height is an obvious advantage

in basketball, high jumping, and most sports emphasizing

strength. Shorter height is an advantage in gymnastics. Differ-

ences 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 students (Carter, Ross, Aubrey, Heb-

belinck, & Borms, 1982). Elite athletes also differ in the size of

their muscles, such as arm girth, and in the amount of fat mea-

sured by skin folds. Endurance athletes have a much higher

aerobic ability, larger hearts, more capillaries supplying blood

to muscles, and a higher percentage of slow-twitch muscle

fibers (Ericsson, 1990). Until quite recently researchers com-

monly believed that percentages of muscle fiber types and aer-

obic 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 gen-

eral characteristics of the nervous system, such as speed of

neural transmission and memory capacities, have a genetic ori-

gin 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 other

basic capacities were remarkably unsuccessful (Guilford, 1967).

Binet (Varon, 1935) started out 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. Be-

cause IQ reflects both environmental and genetic factors, re-

cent research has challenged its interpretation and relation to

successful performance outside the school environment (Ceci,

1990; Howe, 1990). The relation of IQ to exceptional perfor-

mance is rather weak in many domains, including music

(Shuter-Dyson, 1982) and chess (Doll & Mayr, 1987). For scien-

tists, engineers, and medical doctors that complete the required

education and training, the correlations between ability mea-

sures and occupational success are only around 0.2, accounting

for only 4% of the variance (Baird, 1985). More generally, pre-

diction of occupational success from psychometric tests has not

been very successful (Tyler, 1965). In a review of more than one

hundred studies, Ghiselli (1966) found the average correlation

between success-on-the-job measuring and aptitude-test scores

to be 0.19. Aptitude tests can predict performance immediately

after training with an average correlation of 0.3, but the correla-

tion between performance after training and final performance

on the job is only about 0.2 (Ghiselli, 1966). Reviews of subse-

quent research (Baird, 1985; Linn, 1982) have reported very

similar correlation estimates. When corrections were made for

the restriction 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 correlation of 0.5 with early job performance.

However, a recent review (Hulin, Henry, & Noon, 1990) has

shown that 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 corrections for restrictions of

range and unreliability of performance measures). This implies

that ability tests can predict early performance on a job,

whereas final performance is poorly predicted. Even for a 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). Strik-

ing 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 percep-

tion (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 pre-

sented stimuli. But when tested on randomly rearranged ver-

sions 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 individ-

uals.

The domain-specific nature of experts' superior perfor-

mance implies that acquired knowledge and skill are important

to attainment of expert performance. We can cite only two abili-

ties that investigators have argued directly reflect genetic fac-

tors. Some successful musicians can recognize a musical note in

isolation by its pitch (perfect pitch). Championship-level ty-

pists can tap their fingers faster than normal (Book, 1924;

Keele & Hawkins, 1982). Although we claim that genetic fac-

tors have little direct impact on ultimate adult performance, a

plausible role for hereditary factors is in the developmental his-

tory 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-start-

ing 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 deter-

mining 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 perfor-

mance of eminent individuals has been surprisingly unsuccess-

ful. The best evidence for the effect of heritable characteristics

comes from several types of sports, for which anatomical char-

acteristics such as height systematically differ for elite per-

formers 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

Galton'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 envi-

ronmental factors. The most likely source of such unmodifi-

able 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.

Does Practice and Experience Inevitably Lead to

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 improve-

ments. However, with extended efforts, subjects could restruc-

ture their skill to overcome plateaus. Keller (1958) later showed

that these plateaus in Morse Code reception were not an inevita-

ble characteristic of skill acquisition, but could be avoided by

different and better training methods. Nonetheless, Bryan and

Harter (1897, 1899) had clearly shown that with mere repeti-

tion, improvement of performance was often arrested at less

than maximal levels, and further improvement required effort-

ful reorganization of the skill. Even very experienced Morse

Code operators could be encouraged to dramatically increase

their performance through deliberate efforts when further im-

provements were required for promotions and external rewards

(Bryan & Harter, 1897).

More generally, Thorndike (1921) observed that adults per-

form 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 expe-

rience) 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 sup-

port 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, Dea-

ley, and Ford (1936) reported substantial improvements in expe-

rienced typists as a result of deliberate efforts.

Because performance in sports, especially, has been mea-

sured under standardized conditions, and the best perfor-

mance has been recorded at world, national, district, and club

levels, it can be clearly demonstrated that performance has con-

tinually improved during this entire century. Schulz and Cur-

now (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 Tchai-

kovsky 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 addi-

tion 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 prac-

tice leads to maximal performance appears incorrect.

Preparation Time Required for Attainment of

Exceptional Performance

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 no-

tion. 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 indi-

viduals require 10 or more years of preparation to attain interna-

tional-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 (Kro-

gius, 1976).

J. R. Hayes (1981) confirmed that 10 years' experience is

necessary in another domain, musical composition. He calcu-

lated 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 pe-

riod 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, insuffi-

cient 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 contri-

bution 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 pre-

ceded first publication. The average ages at which the same

individuals produced their greatest work were 35.4 for scien-

tists 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 Galton's (1869/1979) claim that motivation and

perseverance are necessary for attainment of eminent perfor-

mance.

Our review has also shown that the maximal level of perfor-

mance for individuals in a given domain is not attained auto-

matically as function of extended experience, but the level of

performance can be increased even by highly experienced indi-

viduals 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 ex-

pert 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 in-

tense prior preparation. However the relation between ac-

quired 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

367

The Role of Deliberate Practice

In this section we characterize deliberate practice—those ac-

tivities that have been found most effective in improving perfor-

mance. 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 per-

formance can be attained through deliberate practice.

Characteristics of 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 read-

ing, 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 in-

vented 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 addi-

tion, the design of the task should take into account the preex-

isting 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 perfor-

mance tend to use easy tasks, where highly accurate perfor-

mance is rapidly attained, and subjects are instructed to in-

crease 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, effi-

cient 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, espe-

cially, accuracy of performance (Trowbridge & Cason, 1932).

When laboratory training is extended over longer time pe-

riods, 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, 1985,1988) show that a small set of general methods

underlie such performance. After being instructed to use ade-

quate strategies, subjects have attained exceptional levels of

memory performance after extended practice (Baltes & Kliegl,

1992; Kliegl, Smith, & Baltes, 1989; 1990).

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 perfor-

mance and collected verbal reports on subjects' cognitive pro-

cesses. These studies revealed subjects' active search for meth-

ods to improve performance and found that changes in meth-

ods 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 dem-

onstrated in date calculation (Addis & O. A. Parsons, as de-

scribed 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. Sea-

shore, 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 tempo-

rarily arrested at suboptimal levels. As the complexity of a de-

sired skill increases beyond the simple structure of most labora-

tory tasks, the logically possible methods to correctly and incor-

rectly perform the task by subjects increase as well. To assure

effective learning, subjects ideally should be given explicit in-

structions about 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 moni-

tor 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 supe-

rior. 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 perfor-

mance by two standard deviations—the average tutored stu-

dent 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 perfor-

mance 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 in-

teraction with learning through active participation. As the lev-

els of performance in the domain increased in skill and com-

plexity, 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 be-

ginners. 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 activ-

ities 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 in-

teraction, paid work, and observation of others, that individ-

uals can pursue in the domain.

Comparison of Deliberate Practice to Other Types of

Domain-Related Activities

Consider three general types of activities, namely, work, play,

and deliberate practice. Work includes public performance,

competitions, services rendered for pay, and other activities di-

rectly 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 re-

quire 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 accept-

able 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 reli-

ability. 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 appli-

cations 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 experi-

ences in which the individual can attend to the critical aspects

of the situation and incrementally improve her or his perfor-

mance 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 recogni-

tion and, most important, money in the form of prizes and pay,

which enables performers to sustain a living. In play and deliber-

ate 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 execu-

tion of an activity (Ravizza, 1984). This state of diffused atten-

tion is almost antithetical to focused attention required by delib-

erate 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 perfor-

mance is carefully monitored to provide cues for ways to im-

prove it further. We claim that deliberate practice requires ef-

fort and is not inherently enjoyable. Individuals are motivated

to practice because practice improves performance. In addi-

tion, 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.

Theoretical Framework for the Acquisition of Expert

Performance

We now outline a framework within which we can explain

how differential levels of performance are attained as a func-

tion of deliberate practice. Our basic assumption—the "mono-

tonic benefits assumption"—is that the amount of time an indi-

vidual is engaged in deliberate practice activities is monotoni-

cally related to that individual's acquired performance. This

assumption can be tested empirically. It follows from this as-

sumption that individuals should attempt to maximize the

amount of time they spend on deliberate practice to reach ex-

pert 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 environ-

ment 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 con-

straint). 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.

Attaining Expert Performance

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 individ-

uals get started and are encouraged to continue. From many

interviews with international-level performers in several do-

mains, 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 deliber-

ate 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 improve-

ments in performance. With increased experience and deliber-

ate practice, individuals' performance in the domain reflects

an inseparable combination of practice and innate talent. We

rely on Bloom's (1985b) characterization of the period of prepa-

ration 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 ex-

tended 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 im-

proving 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 rele-

vant processes. During the decade or two leading to adult ex-

pert 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 neigh-

borhood. At the start of participation in competitions, the refer-

ence 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 interna-

tional level. At increased levels of performance, the practice

activities obviously change and so do the criteria of evaluation.

In the performance of music, children and adolescents are

judged principally on their technical proficiency. Expert adult

performers, however, are judged on their interpretation and

ability to express emotions through music (Sloboda, 1991). The

inability of many child prodigies in music to succeed as adult

musicians (Bamberger, 1986; Barlow, 1952) is often attributed

to difficulties making this transition—possibly resulting from

inappropriate training and instruction during the early and

middle phases of music training. To become outstanding musi-

cians at the international level, individuals have to contribute

unique interpretations of music (Roth, 1982). Similar consider-

ations may explain why mathematical prodigies can fail as

adult mathematicians. The lack of overlap in the performance

of precocious children and adult scientists in mathematics is

even clearer than in music: Superior ability in mental addition

370

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

and multiplication demonstrate efficiency in the mechanics of

mathematics, whereas major adult contributions in mathemat-

ics reflect insights into the structure of mathematical problems

and domains. The criteria for eminent performance goes

beyond expert mastery of available knowledge and skills and

requires an important and innovative contribution to the do-

main. An eminent musician can contribute new techniques and

distinct interpretations of existing music, and eminent chess

players discover new variants of chess openings and advance

the knowledge of chess. In the arts and sciences, eminent

achievements involve contributions of new ideas, theories, and

methods.

In most domains it is impossible to assess retrospectively the

cognitive aspects of the development of precocious exceptional

performers. Precocious painters may be an exception (see J.

Radford's, 1990, review). Pariser (1987) analyzed drawings

completed by Klee, Toulouse-Lautrec, and Picasso until age 20,

and concluded that these three "gifted" individuals encoun-

tered and mastered problems in graphic development in ways

similar to those of the "less-gifted" (p. 53). Their juvenile draw-

ings include "a fair number of awkward, flawed and unexcep-

tional drawings" (Pariser, 1987, p. 65), suggesting that instruc-

tion and practice strongly affected even these three exceptional

artists. The age at which eminent individuals attain their best

performance is much later in their 20s and 30s (Lehmann,

1953). In fact any significant achievements in literature, music

composition, visual arts, and most other domains before age 16

are exceedingly rare (Barlow, 1952). (Judit Polgar and Bobbie

Fischer attained the level of international grandmasters in

chess at age 15; we discuss their developmental history later.)

The methodology we applied in our studies takes these consid-

erations into account as we demonstrate later. At this point we

must further specify the constraints inherent in the attainment

of exceptional performance.

Resource Constraint

International-level performers often receive their first expo-

sure to their domain between the ages of 3 and 8. Obviously,

their parents are responsible for providing this early access.

Parents and guardians, in encouraging the childrens' activity

and monitoring performance, make possible the discovery of

early signs of "talent" and promise. The parents' interest is also

critical in aiding children's transition to deliberate practice and

providing facilities for practice, such as musical instruments for

musicians, tennis courts for tennis players, and ice arenas for

skaters. Bloom (1985a) and his colleagues show that transporta-

tion for young individuals to and from practice, meetings with

the teachers, and competitions can almost completely occupy

parents' free time, and the direct economic costs of sustaining

these activities are substantial. The parents' costs for a national-

level swimmer is estimated by Chambliss (1988) to exceed 5

thousand dollars per year. In many cases, the family is even

willing to move to a location close to the best training facilities

offering year-round opportunities for practice. These extraordi-

nary commitments by parents are probably based on the belief

that their children are somehow special and particularly likely

to succeed. Bloom (1985b) found that there seems to be at least

one central person in a promising child's near environment who

firmly believes, as the child develops, that the child is special,

that is, talented in the domain. This person's belief prevails

even though Bloom (1985b) found no evidence that, during the

early phases, the individual exhibited any clear evidence of pro-

wess. However, Bloom (1985b) found that only one child per

family was considered special. This is perhaps the best empiri-

cal evidence that each family's available resources are limited.

Effort Constraint

The central claim of our framework is that the level of perfor-

mance an individual attains is directly related to the amount of

deliberate practice. Hence, individuals seeking to maximize

their performance within some time period should maximize

the amount of deliberate practice they engage in during that

period. When this time period extends over months and years,

it is clear that maximization of an effortful activity is not simple

and that the traditional research on learning, which is limited

to a few sessions, provides little guidance. In this section, we

review evidence showing that the duration of effective daily

practice that can be sustained for long periods is limited, and

that according to teachers and training instructions, it is neces-

sary to maintain full attention during the entire period of delib-

erate practice. We then discuss some consequences of increas-

ing practice activity beyond its optimal duration and finally

consider evidence that through training the daily duration of

deliberate practice can be slowly increased over extended pe-

riods of time.

The limited duration of practice is the best evidence of the

effort it requires. When individuals, especially children, start

practicing in a given domain, the amount of practice is an hour

or less per day (Bloom, 1985b). Similarly, laboratory studies of

extended practice limit practice to about 1 hr for 3-5 days a

week (e.g., Chase & Ericsson, 1982; Schneider & Shiffrin, 1977;

Seibel, 1963). A number of training studies in real life have

compared the efficiency of practice durations ranging from 1 -8

hr per day. These studies show essentially no benefit from dura-

tions exceeding 4 hr per day and reduced benefits from practice

exceeding 2 hr (Welford, 1968; Woodworth & Schlosberg,

1954). Many studies of the acquisition of typing skill (Baddeley

& Longman, 1978; Dvorak et al.. 1936) and other perceptual-

motor skills (Henshaw & Holman, 1930) indicate that the effec-

tive duration of deliberate practice may be closer to 1 hr per day.

Pirolli and J. R. Anderson (1985) found no increased learning

from doubling the number of training trials per session in their

extended training study. The findings of these studies can be

generalized to situations in which training is extended over long

periods of time such as weeks, months, and years.

The goal of deliberate practice is improved performance, and

detailed analyses of the musicians' activities during practice

sessions in music (Gruson, 1988; Miklaszewski, 1989) reveal

careful monitoring and problem solving by the musicians to

attain the desired improvements. C. E. Seashore (1938/1967),

the pioneering researcher in music psychology, claimed, "Many

a student becomes disgusted with music because he cannot

learn by dull drudgery. The command to rest is fully as impor-

tant as to work in effective learning" (pp. 154-155). Both Auer

(1921), the famous violin teacher, and C. E. Seashore (1938/

1967) recommended that practice periods be limited to less

THE ROLE OF DELIBERATE PRACTICE

371

than 1 hr with ample rest in between. A necessary precondition

for practice, according to Auer (1921), is that the individual be

fully attentive to his playing so that he or she will notice areas of

potential improvement and avoid errors. Auer (1921) believes

that practice without such concentration is even detrimental to

improvement of performance. On the basis of an extended

study of Olympic swimmers, Chambliss (1988, 1989) argued

that the secret of attaining excellence is to always maintain

close attention to every detail of performance "each one done

correctly, time and again, until excellence in every detail be-

comes a firmly ingrained habit" (1989, p. 85).

Deliberate practice aimed at improving strength and endur-

ance in sports clearly shows the importance of near maximal

effort during practice and the resulting fatigue. Physical activity

and exercise produce no benefit unless they are sufficiently

intense. Untrained adults must attain a minimum heart rate of

around 140 beats per minute or 70% of their maximal heart rate

for an extended time at least three times a week to see improve-

ments (Lamb, 1984). However, elite athletes train at much

higher intensities to improve their performance. Athletes train

to maximize their performance in a specific event. In endur-

ance events, such as marathon running, most of the training

consists of running at the highest speed an athlete can maintain

for extended periods. Improvements resulting from training ap-

pear to be more a function of intensity (as close to maximum as

possible) than of the total distance covered (Maughan, 1990). In

sprint events, where runners expend maximal effort for a short

time, strength training is essential (P. F. Radford, 1990). Near

maximal efforts with a 3-s duration produce the most efficient

results for strength training (Klausen, 1990). Obviously such

near-maximal training can be sustained only for limited pe-

riods even if these periods are interspersed with periods of rest.

Other objective indicators of the intensity of athletic training

include measurements of metabolic rate during the activity

(MacLaren, 1990). Athletes need to consume many more calo-

ries than do normal adults simply to sustain their regular train-

ing program (Maughan, 1990). Costill et al. (1988) found that

some swimmers experienced chronic muscular fatigue because

their intake of calories was insufficient to accommodate a re-

cent increase in training activity. The exhausting effects of regu-

lar training are also evidenced by the standard practice of re-

ducing the training level several days before a competition

(Maughan, 1990; P. E Radford, 1990).

Under the assumption that practice draws on limited physi-

cal and mental resources, one would expect that the level of

practice an individual can sustain for long periods of time is

limited by the individual's ability to recover and thereby main-

tain a steady state from day to day. After the individual has

slowly adapted to a constant level of practice, increases ought to

be possible. In contrast, if an individual cannot recover each

day from a given level of practice, sustaining that level will lead

to exhaustion and mental fatigue. The risk of physical injury

and chronic maladaptation will increase "runner's knee," shin

splints, and Achilles tendonitis for athletes (Subotnick, 1977)

and sores, tendonitis, and muscle spasms for musicians (Cal-

dron et al., 1986). Inability to recover from the stress of training,

which is viewed as necessary for improvement in sports, can

lead to "staleness," "overtraining," and eventually "burnout."

These states are characterized not only by physical fatigue and

soreness but also by motivational problems such as lack of en-

thusiasm and even unwillingness to continue with a sport

(Silva, 1990). The only known effective treatment for these con-

ditions "consists of rest, and in some cases, complete abstention

from training and sporting activities may be necessary" (Hack-

ney, Pearman, & Novack, 1990, p. 30).

Early in this century, considerable research was directed to-

ward the subjective experience of mental fatigue and its conse-

quences for performance. On the one hand, efforts to demon-

strate decline in performance, even after consecutive days of

mental multiplication for 12 hr per day, have been remarkably

unsuccessful (Arai, 1912; Huxtable, White, & McCartor, 1946).

On the other hand, the subjective feelings of discomfort and

aversion often become so strong that continuing these experi-

ments beyond 4 days would seem very difficult, if not impossi-

ble. The best data on sustained intellectual activity comes from

financially independent authors. While completing a novel fa-

mous authors tend to write only for 4 hr during the morning,

leaving the rest of the day for rest and recuperation (Cowley,

1959; Plimpton, 1977). Hence successful authors, who can con-

trol their work habits and are motivated to optimize their pro-

ductivity, limit their most important intellectual activity to a

fixed daily amount when working on projects requiring long

periods of time to complete.

When individuals start with deliberate practice in a domain,

the initial duration of weekly practice is limited (Bloom,

1985b). Given that most future international-level performers

start at early ages, these brief durations are consistent with the

short duration (10-20 min per session) of long-term training

programs with children (see Howe, 1990, for a review). Consis-

tent with the idea of slow adaptation to the demands of ex-

tended practice, individuals beginning to practice are encour-

aged to adopt a regular weekly schedule with practice periods of

relatively fixed duration (Bloom, 1985b). After extended time

with an acceptable practice level, individuals adapt their bodies

and lives and can slowly and gradually increase the level of

practice. Too rapid increases in the intensity of practice lead to

"overuse and overtraining," which occur frequently in sports

(Hackney et al, 1990; Silva, 1990) and even in music (Fry, 1986;

Newmark & Lederman, 1987). Bailey and Martin (1988) report

many instances of successful 9- to 11-year-old children increas-

ing their training to very high levels, only to experience motiva-

tional burnout and quit the domain altogether.

In summary, disregard of the effort constraint on deliberate

practice leads to injury and even failure. In the short term,

optimal deliberate practice maintains equilibrium between ef-

fort and recovery. In the long term, it negotiates the effort con-

straint by slow, regular increases in amounts of practice that

allow for adaptation to increased demands.

Motivational Constraint

A premise of our theoretical framework is that deliberate

practice is not inherently enjoyable and that individuals are

motivated to engage in it by its instrumental value in improving

performance. Hence, interested individuals need to be engag-

ing in the activity and motivated to improve performance be-

fore they begin deliberate practice. Bloom (1985b) found evi-

dence supporting this implication. His interviews with interna-

372

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

tional-level performers showed that parents typically initiated

deliberate practice after allowing their children several months

of playful engagement in the domain and after noticing that

their children expressed interest and showed signs of promise.

The social reactions of parents and other individuals in the

immediate environment must be very important in establish-

ing this original motivation.

At the start of deliberate practice, parents help their child

keep a regular daily practice schedule and point out the instru-

mental value of practice for improved performance (Bloom,

1985b). With increased experience and the aid of teachers and

coaches, the developing individual is able to internalize meth-

ods for assessing improvement and can thus concurrently mon-

itor the effects of practice. As individuals get more involved in

the activities of a domain, competitions and public perfor-

mances provide short-term goals for specific improvements. At

this point the motivation to practice becomes so closely con-

nected to the goal of becoming an expert performer and so

integrated with the individual's daily life that motivation to

practice, per se, cannot be easily assessed.

Certain naturally occurring events and changes illuminate

the relation between practice and performance. Activities in

many domains, especially sports, are seasonal because most

scheduled competitions occur during a single season of the

year. If individuals enjoyed deliberate practice, they ought to

practice at a uniformly high level all year. Instead, athletes train

much harder during the preseason period and during the sea-

son itself; during the off season they often reduce the level of

training dramatically (Reilly, 1990a; Reilly & Secher, 1990).

Many individuals who have practiced for a long period of time

give up their aspirations to compete and excel in an activity.

Without the goal of improving performance, the motivation to

engage in practice vanishes. Kaminski, Mayer, and Ruoff

(1984) found that many elite adolescents who decided to stop

competing remained active in the domain but virtually stopped

engaging in practice.

Some individuals have had to terminate their professional

careers for reasons unrelated to their ability to perform. In a

longitudinal study of visual artists, Getzels and Csikszentmiha-

lyi (1976) found that most artists were drawn to painting be-

cause it allowed social isolation. However, aspiring painters

have to promote social relations with art dealers, art critics, and

buyers to gain notoriety, increase the demand for their art, and

generate sufficient sales for full-time artistic activity. Failure to

do so forced many of the best artists to take another job unre-

lated to painting. Once these artists could no longer commit

sufficient time and energy to maintain and improve their per-

formance they stopped painting completely because they could

not accept performing at a lower level. This finding shows that

the activity of painting as such is not inherently motivating but

rather the act of producing art that satisfies the artists' subjec-

tive criteria for quality.

Implications for Empirical Studies

Applied to an individual, our theoretical framework made

three types of predictions: (a) predictions about the develop-

mental history; (b) predictions about current levels and habits

of practice; and (c) predictions about experts' evaluations re-

garding the nature and role of deliberate practice activities that

are relevant throughout development.

Our framework made two important predictions about an

individual's development history. First, the past amount of de-

liberate practice is directly related to the individual's current

performance. More specifically, expert performance is not

reached with less than 10 years of deliberate practice. Second,

deliberate practice starts at low levels and increases slowly over

time. These predictions can be best tested in domains of exper-

tise that are relatively independent of the traditional school

system and where deliberate practice can be easily identified

and measured. It is important that the domain has qualified

teachers who guide individuals in learning basic skills correctly

and direct them toward optimal practice activities. Music is one

such domain, and in the current studies we chose to study

individuals who perform at very high levels on a particular

instrument. To study individuals who had completed the 10-

year period of preparation and had made a commitment to

music as a profession, we contacted the Music Academy in West

Berlin. This academy has an international reputation for its

training program for violinists. Violinists in this program were

asked to provide retrospective reports on their levels of deliber-

ate practice over the years before they entered the academy so

that we might test our predictions.

Next, our framework made several predictions regarding the

current level and related habits in elite performers. First, the

highest improvement of performance, and indirectly the high-

est attained performance, is associated with the largest weekly

amounts of deliberate practice. We predicted that elite per-

formers practice at a constant level from day to day to maxi-

mize improvement over extended periods of time. Further-

more, the daily periods of deliberate practice should be of lim-

ited duration with rest periods in between. In domains with

weekly competitions, stability and equilibrium should occur

over longer time periods such as a week. The extremely effortful

nature of competition, normally on the weekend, would lead to

a reduced load and duration after and just before the competi-

tions.

To obtain information about music performers' current prac-

tice patterns, we asked them to keep diaries. By collecting de-

tailed diaries by these individuals, we could assess the duration

and regularity of different types of activities, in particular those

activities judged to constitute deliberate practice. Drawing on

earlier research on time budgeting (Juster & Stafford, 1985;

Szalai, 1972), we had individuals record at the end of the day all

extended activities with their start and end times. By recalling

already completed activities, individuals who maintain this

diary report should minimize any biasing influence on the fre-

quency and duration of any activity during the day. Further-

more, the instruction to recall the complete sequence of ex-

tended activities during the entire day avoids the bias of focus-

ing on a single activity. This type of diary report is consistent

with Ericsson and Simon's (1984) criteria for valid and unbiased

verbal reports of cognitive processes. This technique is prefera-

ble to an alternative in which subjects are instructed to keep a

selective diary for occurrences of specific problem behaviors,

such as drinking and smoking; the keeping of such a diary

appears to reduce the frequency of these behaviors and thus

yields biased estimates (Hodgson & Miller, 1982).

THE ROLE OF DELIBERATE PRACTICE

373

Large-scale studies have evaluated the accuracy and conver-

gent validity of diary reports by comparing subjects' diary esti-

mates with estimates derived from random time sampling (Ro-

binson, 1985). The diaries were found to underreport activities

of very short duration, such as brief social interactions and

phone calls, a result that is to be expected with diaries focusing

on extended activities. More important for our purposes, the

diary estimates for extended activities were found to be quite

consistent with the results derived from more labor-intensive

methods.

Most of the research using diaries with reported temporal

sequences of activities has been conducted primarily in socio-

logical and economic studies to estimate and project the use of

time in representative national populations (Juster & Stafford,

1985; Szalai, 1972). The goal of this research has been to derive

general categories of activities that allow investigators to reli-

ably classify any one of the reported activities into one of a

limited number of categories. At the highest level, the activities

can be grouped into categories, such as sleep, work, and leisure.

In studying the daily lives of expert performers, we can draw on

this previously developed classification for general activities,

but we must supplement it with an analysis of the activities

relevant to the particular domain of expertise under investiga-

tion.

As to the third point, our framework made predictions about

the qualities of various domain-related activities, such as delib-

erate practice. We predicted that deliberate practice would be

rated very high on relevance for performance, high on effort,

and comparatively low on inherent enjoyment. We could evalu-

ate ratings by expert individuals to determine the extent to

which deliberate practice is perceived to have these attributes.

The central prediction from our framework was that the

adult elite performance, even among individuals with more

than 10 years of practice, is related to the amount of deliberate

practice. This prediction contradicts Galton's (1869/1979) mo-

dal view outlined earlier that eminent performance reflects pri-

marily innate talent after sufficient practice and that, by impli-

cation, practice and elite performance are not related. However,

often talent is contrasted with practice, where the best individ-

uals are assumed to practice less than individuals with inferior

performance. Finally, plausible alternative hypotheses also sug-

gest that the most talented individuals would practice more.

These hypotheses imply a high correlation between innate tal-

ent and practice. Because our studies were not designed to ad-

dress the last possibility, we do not consider it except in the

General Discussion section.

Study 1 compared the current and past levels of practice in

three groups, elite violinists judged to have promise for careers

as international soloists and two groups of less accomplished

expert violinists. Study 2 replicated the results of the first by

comparing expert and amateur pianists. In addition, it related

estimates of the amount of prior practice to current perfor-

mance on a wide range of musical and nonmusical tasks for all

pianists.

Study 1

We assessed current and past levels of deliberate practice in

three groups of elite, adult violinists whose current perfor-

mance differed. First we identified the activities constituting

deliberate practice. We then determined the duration and orga-

nization of deliberate practice and contrasted them for the

three groups.

Method

Subjects

The music professors at the Music Academy of West Berlin (Hochs-

chule der Kuenste) nominated violin students who had the potential for

careers as international soloists. Out of 14 students nominated, 3 were

not fluent in German and 1 was pregnant. The remaining 10 students

agreed to participate in the study and are called "the best violinists."

The music professors also nominated a large number of good violinists

in the same department. From these subjects, we selected 10 violinists,

"the good violinists," by matching their sex and age to those of the best

violinists. Similarly, we recruited 10 students specializing in the violin

from a different department (music education) in the academy, which

has lower admissions standards. Again, we matched these students' sex

and age to those of the violinists in the best group. We call the students

from the department of music education the "music teachers" because

teaching is the most likely future profession for this group. To obtain

additional data on the developmental history of outstanding violin-

ists, we interviewed 10 middle-aged violinists who belong to two sym-

phony orchestras in West Berlin with international reputations, the

Berlin Philharmonic Orchestra and the Radio Symphony Orchestra

(RSO). According to the professors at the music academy, the most

likely professional career for the best young violinists is to perform as

a member of one of the best symphony orchestras in Germany.

Procedure

The data-collection procedures for the best and good violinists and

the music teachers were identical. The first part of the procedure for

the middle-aged violinists, from which data are reported, was the same

as for the three groups of young violinists.

Each young violinist was interviewed during three sessions. During

the first session biographical information was obtained including the

start of practice, sequence of music teachers, and participation in com-

petitions. The subjects were then asked to estimate how many hours

per week they had practiced alone with the violin for each year since

they had started to practice.

Each subject was then given instructions about a taxonomy of activi-

ties. Ten categories of everyday activities were presented, each with a

general label and description and a listing of frequent examples. From

extensive pilot work, 12 categories of musical activities were identified

and similarly presented. Musical and everyday activities are listed in

Table 1. For those subjects playing other instruments besides the vio-

lin, the eight musical categories for playing an instrument were split

into activities involving the violin and activities involving all other

instruments. After presentation of the taxonomy, subjects were asked

to estimate how much time they spent on each type of activity during

the most recent typical week. Subjects were also asked to rate each of

the activities on three dimensions using a scale from 0-10. First they

were asked to rate the relevance of the activity to improving perfor-

mance on the violin. Next they were asked to rate the effort required to

perform the activity. Finally, they were asked to rate how enjoyable the

activity was without considering their evaluation of the result of the

activity. (For example, it is possible to enjoy the result of having cleaned

one's house without enjoying the activity of cleaning.)

During the second session, subjects answered questions about prac-

tice and concentration. They also recalled all activities they had en-

gaged in during the previous day. For this recall they used a specially

374

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

Table 1

Mean Relevance, Effort, and Pleasure Ratings for 12

Music-Related and 10 Everyday Activities Collapsed

Over Three Groups of Yo ung Expert Violinist s

Activities Relevance Effort Pleasure

Music related

Practice (alone) 9.82 H 8.00 H 7.23

Practice

(

with others

)

8.73 H 6.97 H 7.57

Playing for fun

(

alone

)

5.67 3.27 L 8.33 H

Playing for fun

(

with others

)

6.67 3.93 8.60 H

Takin

lessons 9.63 H 8.60 H 7.67

Giving lessons 7.03 7.51 H

6.79

Solo

erformance 9.03 H 9.80 H 7.28

Group performance 7.67 H 8.14 H

8.07 H

Listenin

to music 8.33 H 4.38

8.38 H

Music theory 7.63 H 6.37 H 6.07

Professional conversation 6.50 4.33 6.40

Organization and

aration 2.90 L 4.70 1.53 L

Everyday

Household chores 1.80 L 2.23 L 3.63 L

Child care 2.64 L

6.14

6.43

Shopping 0.77 L 2.80 L 3.97 L

Work (not music related) 1.79

5.5

3.74 L

Bod

care and health 4.90 1.43 L 5.23

Sleep 8.17 H 0.47 L 7.70

Education (not music) 4.52

5.45

7.17

Committee work 1.93

5.55

5.07

Leisure 6.30 3.00 L 8.93 H

Sports 6.07 2.67 L 7.07

Grand mean 5.89 5.03 6.52

Note. N = 30, unless shown with a superscript. (Some subjects could

not make their ratings because of a lack of familiarity with the activity

in question.) The grand means over all activities and information about

the significant deviation from the grand mean is given based on post

hoc analyses using Bonferroni's method. The statistical test is conser-

vative as the grand mean includes the ratings for the particular activity

in the respective comparison. H = significantly higher than grand

mean; L = significantly lower than grand mean.

N=29.

N=28.

N=27.

designed diary sheet that divided the 24-hr day into ninety-six 15-min-

ute intervals. Use of the sheet ensured that the start and end of recalled

activities covered the entire 24-hr day. After completing the recall,

subjects were asked to encode the activities using the 30 categories in

the taxonomy. Following the second session, subjects kept a diary us-

ing the provided sheets for a full 7-day week. Subjects were given enve-

lopes addressed to the investigators and sent in their diaries after each

day. Before returning for the third and final interview session, the

subjects, working from copies of their diaries, encoded each activity

according to the taxonomy. Subjects were encouraged to identify the

primary category for each activity but they were allowed to use more

than one category to encode mixtures of activities, such as a profes-

sional discussion during lunch. At the beginning of the third interview

session, subjects were allowed to ask any questions they had about

their encoding. During the remaining part of the session the inter-

viewer asked questions about the subjects' developmental life goals

and engaged in general debriefing.

Results

Our analyses focus on young violinists' allocation of time for

relevant preparatory activities as revealed by their diaries and

retrospective estimates of practice during their development. In

preparation for this analysis, we briefly describe the biographic

data and other data relevant to systematic differences in the

violin performance of the three groups of young violinists and

analyze each group's ratings of everyday and musical activities

regarding relevance, effort, and enjoyment.

The three groups of subjects were selected such that the per-

formance of the best violinists should be better than that of the

good violinists, whose performance in turn should be better

than that of the music teachers. In the following statistical anal-

yses, the hypothesized differences between the three groups of

violinists are represented by two orthogonal contrasts. The first

contrast refers to the average difference between the best and

the good violinists. The second orthogonal contrast compares

the average of the best and good violinists (referred to as the

soloist students) to that of the music teachers. In statistical anal-

yses that include the developmental history of middle-aged pro-

fessional violinists, the data from this group are contrasted

with those of the group of the best young violinists.

Biographic Information

All three groups of young violinists consisted of 7 women

and 3 men. The middle-aged professional violinists were all

men. The ages of the young subjects were successfully matched,

and no reliable differences in age were found. The mean age of

young violinists was 23.1 years old. The mean age of the profes-

sional violinists was 50.5 years old.

The biographic histories of the four groups of subjects with

respect to violin playing are remarkably similar and show no

systematic differences between groups. The age when they be-

gan practice was 7.9 years old and essentially coincided with

the age of starting systematic lessons, which was 8.0-years-old.

The age at which they first decided to become musicians was

14.9 years old. The average number of music teachers who had

taught them was 4.1, and the average number of musical instru-

ments that they had studied beyond the violin was 1.8.

The best indicator of violin performance, besides the evalua-

tion of the music professors, is success at open competitions. A

statistical analysis of the number of successful entries in violin

competitions confirmed systematic differences in performance

among the three groups of young violinists. The frequencies for

the best and good violinists were reliably different, 2.9 vs. 0.6;

F(\, 27) = 19.35, p < .01. The average frequency of the best and

good violinists differed from that for the music teachers, 1.8 vs.

0.2; F(i, 27) = 11.78, p < .01. The same pattern of results

emerged when the proportion of successful entries from all

participations was analyzed. The young violinists were also

asked to estimate in minutes of playing time how much music

they could perform from memory without preparation. The

best violinists reported an average of 128.9 min, which is longer

than the 79.1 min reported by the good violinists, F(l, 27) =

4.07, p < .05. The average playing times for the best and good

violinists were longer than that of the music teachers, 104.0 vs.

42.27; F(l, 27) = 8.23, p < .015.

In sum, all four groups had a similar musical background,

and by the age of 23 (the mean age of the young violinists), all

40 subjects had spent at least 10 years practicing the violin.

THE ROLE OF DELIBERATE PRACTICE

375

Ratings of Everyday and Musical Activities

In analyzing the ratings of relevance to improving violin per-

formance, effort, and enjoyment of the everyday and musical

activities, our primary goal was to identify a smaller set of activi-

ties rated critical to improvement of violin performance by all

young violinists. Analyses of each set of ratings for the 22 activi-

ties for the three groups of young violinists revealed no profile

differences, that is, interactions between group and ratings of

activities, which could account for differences in their actual

allocation of time to different types of activities. We therefore

collapsed the further analyses of differences in ratings between

various activities across the three groups of young violinists.

For each type of rating (relevance, effort, and enjoyment) we

compared the mean rating across all activities with the mean

rating of that activity. The significance of differences was deter-

mined from adjusted alpha levels (a* = a/22 = 0.0023). The

mean ratings and information about significant differences are

given in Table 1.

As shown in Table 1, subjects reliably rated 7 of the 12 musical

activities as more relevant than the overall mean. Consistent

with our theoretical assumption, 27 of the 30 violinists gave

"practice alone" the highest relevance rating. In contrast, play-

ing alone for fun, which an observer would have difficulty dis-

criminating from practice alone, received a much lower rele-

vance rating. Out of the 10 everyday activities, only sleep was

rated as reliably more relevant to improving one's violin perfor-

mance than the grand mean, and 5 activities were rated reliably

less relevant. Many of the activities with the highest relevance

ratings are constrained by external factors and resources. For

example, the duration of taking lessons and public perfor-

mance alone and in a group cannot easily be increased at the

will of the subject. Similarly, practice in groups is to a lesser

degree constrained. After these additional criteria are applied,

there remain four relevant activities of which the violinists can

easily control the duration: practice alone, music theory, listen-

ing to music, and sleep.

The ratings of effort associated with different activities show

that six of the eight activities judged to be highly relevant to

performance improvement are also judged to require reliably

more effort than the average activity. The two exceptions are

listening to music and, not surprisingly, sleep, which is judged

reliably less effortful than the average activity. The ratings of

inherent pleasure show that only two of the eight highly relevant

activities—listening to music and group performance—are

also judged to be reliably more pleasurable than the average

activity.

In sum, all three groups seem to have the same conception of

the relevance of different activities for improvement of violin

performance, and all three similarly evaluate the inherent en-

joyment and effort associated with different activities. We now

turn to the analysis of the time each group allocated to different

activities and, in particular, to activities judged to be highly

relevant for improving violin performance.

Diaries

From the detailed diaries with encoded activities, the total

time a violinist spent during the week on any one of the activity

categories can be calculated by simple addition. Most of the

encoded activities were described by a single category, such as

exclusive categories like sleep and practice; but some activities,

such as a professional discussion over dinner, were given multi-

ple encodings. When activities were given multiple encodings,

the time of the activity was split equally among the associated

categories.

When the duration of all music-related activities was

summed across the diary week, the average number of hours

per week was 50.6, and no reliable differences between the

groups were found. Of the eight activities judged to be highly

relevant to improvement of violin performance, only two had

an average duration across all three groups exceeding 5 hr per

week. These two activities were practice alone (19.3 hr per

week) and sleep (58.2 hr per week).

Practice alone. In agreement with our theoretical frame-

work, violinists rated practice alone as the most important activ-

ity related to improvement of violin performance. Practice

alone is a particularly interesting activity because the violinists

themselves control its duration and distribution during the

week. In contrast, most other activities judged to improve vio-

lin performance, such as public solo performance and taking

lessons, are highly constrained by external factors. We analyzed

the total duration of practice alone for the three groups and

then examined the distribution of practice alone during the

week.

During the diary week, the average duration of the violinists'

practice alone with the violin did not differ for the two best

groups and averaged 24.3 hr of practice. This average was reli-

ably greater than that for the music teachers who practiced 9.3

hr per week, F(l, 27) = 44.05, p < .001. As the first step in

analyzing the distribution of practice, we analyzed the daily

amount of practice as a function of the day of the week for the

three groups. No main effect or interaction of the day of the

week was observed, and only the contrast found earlier between

the two best groups and the music teachers was reliable. The

two best groups practiced alone for 3.5 hr per day and the music

teachers for 1.3 hr per day for each day of the week including the

weekend. As the second step, we assessed the frequency of

practice as a function of time of day. The frequency distribu-

tions across all weekdays shown in Figure 2 suggest a prefer-

ence by the two best groups for practicing alone before lunch,

whereas no corresponding pattern is observed for the music

teachers.

For statistical analyses, the percentage of time each violinist

spent practicing alone was calculated for the five 2-hr intervals

from 10:00 am to 8:00 pm for each day of the week. An analysis

of variance (ANOVA) revealed no main effects or interactions

involving the day of the week and no systematic differences

between the two best groups. The two best groups spent a

greater proportion of time on practice alone than the music

teachers did, F(l, 27) = 59.11, p < .001, and this difference

interacted with the time of day, F(4,108) = 2.94, p < .05. A post

hoc analysis showed that the time music teachers practiced

alone was distributed uniformly across the day, whereas the two

best groups had elevated levels of practice between 10:00 am

and 2:00 pm. This interaction and the main effect of time of

day, F(4,108) = 6.09, p < .001, are shown in Figure 3.

Consistent with the rated effortfulness of practice alone, the

376

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

time requirement for the music teachers was for the most part

balanced out by the longer duration of activities relating to

public performance by the two best groups.

Sleep. The high relevance of sleep for improving violin per-

formance must be indirect and related to the need to recover

from effortful activities such as practice. Consistent with the

ratings, sleep is the least effortful of the activities and thus con-

stitutes the purest form of rest. The weekly amount of sleep

during the diary week did not differ for the two best groups and

averaged 60.0 hr. This average was reliably longer than that for

the music teachers, which was 54.6 hr, F(1, 27) = 5.02, p < .05.

Hence the two best groups, who practice more, also sleep reli-

ably longer.

An ANOVA of the amount of sleep as a function of day of the

week for the three groups showed no main effect or interaction

with day of the week. The average amount of sleep per day was

8.6 hr for the two best groups and was reliably longer than 7.8

hr of sleep for the music teachers. Large-scale diary studies

from several different countries show that adults sleep on aver-

age 8 hr per day (Converse, 1972) and that adults sleep about 1 to

V- hr more on the weekend than they do during the work week

(Robinson, Converse, & Szalai, 1972). Laboratory studies show

that the amount of sleep differs as a function of age (Roffwarg,

Muzio, & Dement, 1966). A recent study by Robinson,

Andreyenkov, and Patrushev (1988) shows that adults between

18 and 29 years of age sleep around 7.7-7.9 hr per day, a finding

that is remarkably consistent with our estimate for the music

teachers. The distribution of the frequency of sleeping as a

function of the time of the day is shown in Figure 4 for the three

groups.

The two best groups appear to sleep more during the after-

noon. The duration of sleep episodes separated from nighttime

sleep by at least 1 hr from 9:00 am to 9:00 pm was not reliably

different for the two best groups and averaged 2.8 hr per week.

This average differed reliably from that of the music teachers,

F(l, 27) = 5.92, p < .05, who napped only 0.9 hr per week. The

two best groups did not take longer naps to compensate for

deficits in nighttime sleep because, when napping was sub-

tracted from the total sleep time, the mean for the two best

duration of sustained practice is limited. Most interestingly, the

duration of practice sessions is very similar to other estimates of

optimal practice duration reviewed in this article. The mean

duration of practice sessions during the diary week did not

differ during that week and averaged 80 min with no reliable

differences among groups. Hence, the differences in amount of

practice reflected differences in the number of practice ses-

sions. The two best groups did not differ reliably and had an

average of 19.5 sessions per week, a number that was reliably

more than the average of 7.1 sessions per week for the music

teachers, F(l, 27) = 22.40, p < .001.

The differences in practice alone between the two best

groups and the music teachers might be due to very different

curricula in the two departments at the Academy. However, a

careful comparison revealed only minor differences between

the two departments' training requirements in music. The mu-

sic teachers had additional requirements consisting of pedagogi-

cal aspects of music education, but these requirements corre-

sponded to less than 5 hr during the diary week. This increased

THE ROLE OF DELIBERATE PRACTICE

377

groups was higher than that of the music teachers, although the

difference was no longer reliable.

An analysis of napping as a function of day of the week for

the three groups showed no main effect of weekday, but did

show a significant interaction between day of the week and the

contrast between the two best groups and the music teachers,

F(6,162) = 2.22, p < .05, which is illustrated in Figure 5.

The overall pattern in Figure 5 suggests that the amount of

napping is uniformly low for the music teachers, whereas the

amount of napping for the best and good violinists is elevated at

the beginning of the work week and reaches its lowest levels

during the weekend. Further analysis revealed that the primary

source of the interaction reflects differences between the week-

end and the five weekdays. An ANOVA of the amount of nap-

ping for the three groups revealed a reliable difference between

the weekend and the work week, F(l,27)=4.29,p< .05, and an

interaction with the difference between the best and good vio-

linists and the music teachers, F(l, 27) = 12.06, p < .005. Given

our general argument for recovery from practice through rest

and the result that levels of napping decreased over weekends

whereas the amount of practice did not, we looked for alterna-

tive sources of rest that could moderate the amount of napping

required over the weekend. Of the other activities rated high on

restfulness, that is, rated low on effortfulness, leisure has the

longest weekly duration during the diary week, with 28.2 hr per

week. Thus, we now consider the role of leisure activity in pro-

viding recovery from practice.

Leisure. We performed an ANOVA of the daily amount of

leisure activities as a function of the day of the week for the

three groups. The best violinists spent 3.5 hr per day on leisure,

which is reliably less than the 4.7 hr for the good violinists, F(\,

27) = 4.27, p < .05. The average for the best and good violinists

was 4.1 hr of leisure per day, which is not reliably different from

the mean for the music teachers (4.0 hr). In comparison, other

adults aged 18-29 are estimated to spend around 5.2 hr a day on

leisure activities—defined as Robinson et al.'s (1988) estimate

of free time with sports and education excluded. An ANOYA of

the leisure time as a function of the day of the week for the three

groups of violinists revealed no reliable interactions, but a reli-

able main effect of weekday was observed, F(6,162) = 5.59, p <

.001, and is shown in Figure 6.

A post hoc analysis using Bonferroni's t tests showed that out

of the 21 possible paired comparisons, only 9 reached signifi-

cance. All 9 involved comparing a weekday to either Saturday

or Sunday, a finding that implies that leisure time is reliably

elevated during the weekend. This pattern is consistent with

the hypothesis that activities other than sleep can provide neces-

sary rest. The finding that the best violinists spend less time for

leisure is important because leisure is judged to be the most

enjoyable of all activities, as reflected by the ratings of inherent

pleasure in Table 1. For all young violinists there is a reliable

negative correlation between amount of leisure time and

amount of time on music-related activities, r(28) = —0.37, p

<.O5.

Estimates of Weekly Duration of Various Activities

It is possible that some of the results found with the time-con-

suming method of collecting and analyzing diaries could have

378

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

been obtained with more efficient methods. In this section we

analyze the time these students estimated spending on the dif-

ferent activities during a current week as well as their retrospec-

tive estimates for the time they practiced alone earlier in their

career. We first consider the estimates for a current typical

week, which the violinists made prior to the diary week. Esti-

mates for practice alone are reported, then the estimates for

sleep and leisure.

Our analysis of the diaries showed that the violinists main-

tained practice alone with the violin at a stable level across the

entire week. We therefore expected that they could accurately

estimate the amount of weekly practice on the basis of their

daily practice. An ANOVA of the estimated weekly amount of

practice revealed no reliable differences between the two best

groups of violinists, who estimated 29.8 hr of practice alone.

The two best groups were found to estimate a reliably greater

amount of practice than the music teachers did, 29.8 vs. 13.4;

F{\, 27) = 38.68, p < .001. A repeated-measures ANOVA, in-

cluding the estimates for the current week and the diary data,

revealed that the estimates for the current week were reliably

higher by 5.2 hr than the amount assessed from the diaries, F(l,

27) = 15.39, p < .001, and that this overestimate did not differ

across the three groups. The two measures of practice alone

were highly correlated for all young violinists, r(28) = 0.74,

/?<.001.

A closer analysis revealed that 85% of the best two groups

and 50% of the music teachers expressed their estimated weekly

amount of practice during the typical week as a daily amount

multiplied by 7 days or as an integer value that was an exact

multiple of seven. Debriefing interviews suggested that the esti-

mates for a typical week reflected a level of daily practice to

which the violinists aspired rather than the level they actually

attained. Hence estimates of weekly practice appear to be va-

lid, albeit biased, indicators of actual practice, and the bias

does not differ among the three groups.

The estimates of sleep during a typical week revealed no

differences between the best and good violinists, but a reliably

higher average for the best and good than the mean for the

music teachers, F( 1, 27) = 5.42, p < .05. A repeated-measures

ANOVA for estimated sleep and sleep assessed by the diary

revealed no differences between the best and the good violin-

ists, but a reliable main effect for the contrast between the best

and good violinists and the music teachers, F(\, 27) = 7.21, p <

.05. The estimates indicated 3.5 hr of sleep less per week than

the diary measure, F(l, 27) = 10.19, p < .005, and there were no

reliable interactions with the group contrasts. The correlation

between estimated sleep and sleep assessed through the diaries

was reliable, r(28) = 0.49, p < .01. Most of the violinists (83%)

estimated their weekly sleep as a multiple of seven.

The estimated amount of leisure revealed a different pattern

of results than that assessed from the diaries. An ANOVA un-

covered no differences between the best and the good violin-

ists, but reliably lower estimates for the music teachers than the

average for the best and good violinists, F(\, 27) = 5.25, p < .05.

A repeated-measures ANOVA for the estimated amount of lei-

sure and the amounts derived from the diaries found no reliable

main differences between groups. The estimated amount of

leisure was 7.4 hr lower than that derived from the diaries, F(l,

27) = 13.46, p < .001, and the interaction of the difference

between the best vs. the good violinists was reliable, F(l, 27) =

6.66, p < .05. The estimated amounts of leisure and the

amounts of leisure assessed from the diaries are shown for all

three groups in Figure 7.

The best violinists, who spent the least amount of time on

leisure, made estimates closely matching the amounts mea-

sured for the diary week. The estimates of the other two groups

are much lower than the leisure time measured for the diary

week. Not surprisingly, the correlation between estimates and

diary assessments was low, r(28) = .082, p > .05. Only half of the

subjects estimated the weekly leisure time as a multiple of

seven.

In sum, the violinists could give reasonably accurate esti-

mates of the weekly duration of stable, habitual activities, such

as sleep and amount of practice alone. All subjects, except those

THE ROLE OF DELIBERATE PRACTICE

379

in the best group, were very inaccurate in their estimates of

spontaneous activities such as leisure time.

Retrospective Estimates of Practice During Musical

Development

Our findings on practice alone imply that subjects should be

able to accurately report not just their current level of practice,

but past levels of practice as well. Practice alone is viewed as the

most important activity for improvement of violin perfor-

mance, and its daily amount is remarkably stable. The effortful

nature of practice suggests that subjects monitor its duration

carefully and hence should be able to estimate it even after long

retention intervals. Our earlier analyses showed that concurrent

estimates of weekly duration of practice alone are highly corre-

lated with the durations recorded in the diaries. These retro-

spective estimates are likely to have a larger error component,

but they should not be systematically biased. The one caveat is

that subjects might report the level of practice to which they

aspired rather than the actual amount. However, the correla-

tion between aspired and actual amounts appears to be quite

high for all three groups of young violinists. In addition, the

widely held view that very talented musicians need to practice

less than other musicians would yield a bias in the opposite

direction of what the skill-acquisition framework predicts;

namely, the best or "most talented" violinists would be inclined

to underestimate their past amount of practice to support their

beliefs that they are very talented.

At the end of the extended biographical interview, all of our

subjects estimated the average number of hours of practice

alone with the violin per week for each year since they had

started playing the violin. Figure 8 illustrates that for all four

groups the reported amount of practice increases monotoni-

cally from the start of practice until the age of 20.

The theoretically most interesting index of amount of prac-

tice is the total amount of practice accumulated at a given age.

The weekly estimates of practice alone can easily be converted

to estimated yearly amounts by multiplication of the number of

weeks in a year. The number of hours of practice accumulated

by a violinist at a given age can be easily calculated by adding

the yearly estimates at and below that age. The average number

of hours of accumulated practice for each of the four groups is

shown in Figure 9 as a function of age.

To avoid any confounding influences from the activities at

the music academy, we statistically analyzed the amount of

practice the young violinists had accumulated by age 18. At this

age, the best young violinists had accumulated an average of

7,410 hr of practice, which is reliably different from 5,301 hr,

the average number of hours accumulated by the good violin-

ists, F(l, 27) = 4.59, p < .05. The average of the best two groups

was reliably different from that of the music teachers, who had

accumulated 3,420 hr of practice by age 18, F(l, 27) = 11.86, p <

.01. Hence, there is complete correspondence between the skill

level of the groups and their average accumulation of practice

time alone with the violin.

380

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

A further test of the relation between performance and prac-

tice is provided from the amount of practice accumulated by

the professional middle-aged violinists at age 18. The average

for middle-aged violinists is 7,336 hr, which is so close to the

average of 7,410 hr for the best young violinists, that the differ-

ence is not statistically significant. Presumably the middle-

aged violinists were selected by international-level orchestras

because they had the same skill level in early adulthood as the

best young violinists currently have. The high degree of corre-

spondence between these two groups' retrospective estimates

of practice alone during their music development thus supports

the validity of these estimates.

Summary of Results of Study 1

Confirming our theoretical framework, the violinists in all

groups rated practice alone as the most relevant activity for

improving violin performance. Among all the activities rated

highly relevant, practice alone is unique: A violinist can extend

its duration at will because no external resources, such as avail-

ability of teachers or audiences, are involved. An analysis of the

week-long diaries showed that the two best groups of young

violinists did not differ from each other in their amount of

practice alone with the violin, but they practiced almost three

times longer than the music teachers. The violinists were able

to estimate their weekly practice, and their estimates were

highly correlated with the calculated durations from the diary

week. From retrospective estimates of weekly practice during

their musical development, the amount of accumulated esti-

mated practice alone by age 18 was calculated. The accumu-

lated amount of practice for the best young violinists was indis-

tinguishable from that of professional middle-aged violinists

belonging to international-level orchestras. This finding was

expected because the most likely professional career for the

best violinists is membership in a first-rate orchestra. The good

violinists had accumulated fewer hours of practice alone by age

18, but reliably more than the music teachers had.

Beyond the internal consistency of the retrospective esti-

mates of practice alone, it is possible to compare the weekly

estimates from our study to concurrent estimates of amounts of

practice by young award-winning musicians from two German

studies (Kaminski et al., 1984; Ruoff, 1981). These musicians

are biographically similar to the violinists in our best group

and were assessed with a diary procedure at two different ages.

At age 13 the award-winning musicians practiced 13.7 hr per

week (Ruoff, 1981), an amount close to the 12.2 hr estimated by

our best group and higher than the 8.8 and 6.2 hr per week

estimated by the good and music teacher groups, respectively.

At age 17, the practice of the award-winning musicians averaged

15.5 hr per week (Kaminski et al., 1984) compared with the

19.2,16.8, and 9.1 hr per week estimated by the best, good, and

music teacher groups. The agreement between the estimates of

our best violinists and the award-winning violinists' diary data

is reasonably close and is consistent with the hypothesis that the

best violinists practice more than the good violinists during

early adolescence and more than the music teachers during

their entire developmental period. In a recent study Sloboda

and Howe (1991) interviewed more than 40 students (aged 10-

18) in a music school, where about half of the students were

superior to school standards. They found no reliable difference

in the estimated amount of daily practice between their two

groups of superior and average musicians. The difference be-

tween the results and our own can be explained by the more

select samples of musicians studied by us and Kaminski et al.

(1984). Consistent with this interpretation, the estimated

amount of daily practice for their subjects was only half that of

our subjects' estimates for the comparable age period. Further-

more, only a fraction (14%) of Sloboda and Howe's (1991) sub-

jects were totally self-motivated to practice, which raises some

issues as to whether the practice of most of their subjects meets

the criteria for deliberate practice.

Consistent with our theoretical framework, the violinists

rated practice alone as requiring effort. The analysis of the diar-

ies revealed that uninterrupted sessions of practice alone were

limited to a duration between 1 and 1.5 hr, a finding that is

consistent with extended laboratory studies on practice. For the

two best groups practice was systematically distributed during

the day and was particularly high in the late morning. Two

findings provide intriguing evidence of the effortful character

of practice. First, violinists rated sleep as highly relevant for

improvement of violin performance. Second, the analysis indi-

cated that the violinists napped to recover from practice. The

two best groups of violinists with the highest levels of practice

were found to nap more in the afternoon than did the group of

music teachers. Furthermore, the duration of napping de-

creased during the weekend, when ample time for relaxing activ-

ities such as leisure was available. Another study provides simi-

lar findings. World-class musicians interviewed by Samuel

(1987) rated practice as extremely important, especially during

development. A majority of these subjects (65%) judged sleep as

important, and many musicians reported taking afternoon

naps, especially before a public performance.

The diary-based analyses of the amount and distribution of

practice showed clear differences between the music teachers

and the two best groups, but no difference between the two

best groups. The two more accomplished groups differed in the

accumulated amount of estimated practice, and the best group

spent less time on leisure than the good group did during the

diary week. Most interestingly, the subjects in the best group

were able to estimate quite accurately the time they allocated to

leisure, whereas the good violinists underestimated their lei-

sure time during the diary week by more than 11 hr. With our

finding that, compared with the good violinists, the best vio-

linists tended to spend more time on music-related activities,

these results suggest that our most accomplished subjects show

a greater involvement in music and organize their time better,

especially their leisure time.

It is important to note that our study shows only that the

amount and distribution of practice is related to the level of

performance of adult musicians. In fact, many additional fac-

tors consistent with the skill-acquisition framework could atten-

uate the differences among our three groups. Sosniak (1985)

found that international-level pianists had spent considerable

efforts to seek out the very best musical teachers during their

musical development. Furthermore, it is likely that an analysis

of the detailed activities during practice alone would reveal

qualitative differences between violinists at different advanced

levels of performance (Gruson, 1988; Miklaszewski, 1989).

THE ROLE OF DELIBERATE PRACTICE

381

Study 2

The purpose of the second study was to extend the findings

from the violinists to another domain of expertise and, most

important, to obtain experimental measures of performance in

skill-related tasks that could then be related to measures of

current and accumulated practice. To determine whether the

previous findings could be replicated for subjects with more

extreme differences in proficiency than the violinists had, we

compared a group of young expert pianists with a group of

amateur pianists. The data reported in this study are from a

larger investigation including two more groups, one of elderly

professional pianists and another group of elderly amateur

pianists. Recent research on expert piano performance

(McKenzie, Nelson-Schultz, & Wills, 1983; Palmer, 1989;

Shaffer, 1981; Sloboda, 1983) has shown that it is possible to

record the sequence of piano keystrokes and analyze motor

skills differentiating pianists at different levels of performance.

In his dissertation Krampe (1991) designed a battery of tasks

ranging from nonmusical tasks, such as choice reaction time, to

actual performances of a musical piece to study four groups of

expert vs. amateur and younger vs. older pianists. Unfortu-

nately, we could not find a large group of young pianists who

met the selection criteria used for the best violinists in Study 1.

Instead, we recruited a sample of expert pianists from the Mu-

sic Academy of Berlin according to selection criteria similar to

the good violinists in Study 1. The amateur pianists were

matched for sex and equated for mean age with the expert pian-

ists.

As with Study 1 we first provide biographical data, then the

report of the 1-week diary and retrospective estimates of past

practice. We report on the battery of nonmusical and musical

tasks and finally relate the performance on the musical tasks to

our estimates of accumulated practice. Our main prediction

was that we would be able to predict differences in proficiency

in the skill-related tasks at least as well from our measures of

accumulated practice as from the differences in the pianists'

level of expertise.

Method

Subjects

Twelve expert pianists (8 men and 4 women) and 12 amateurs (7 men

and 5 women) equated for mean age (24.3 years) participated in the

study. The expert pianists were students in advanced soloist classes at

the "Hochschule der Kuenste," a Berlin music academy. All expert

pianists were students but had already started to perform in public

concerts. Fifteen amateurs recruited through newspaper and campus

ads were students in academic or vocational training programs. To

make the amateurs comparable to the experts, we specified that the

amateurs had to play classical music and be able to successfully play a

piece by Bach used in the musical performance task. Three amateurs

failed this criterion. The estimates of practice alone during early devel-

opment were also collected from two age-matched samples of 12 older

experts and 12 amateur pianists with the average age of 59.8 years.

Apparatus

An electronic keyboard (Yamaha CB-300 Clavinova) and a MacII

computer were used for monitoring experiments and collecting data

for all tasks except for the digit-symbol substitution test. That test was

administered in the paper-and-pencil version.

Procedure

Data were collected during two sessions separated by 7-12 days.

During the first session subjects participated in an abbreviated version

of the interview in Study 1. They provided detailed biographical infor-

mation and estimated the average amount they had practiced alone

every week for each year of their lives since they started practicing.

Then followed the first experiment, the complex movement coordina-

tion task, which challenged the speed and accuracy of subjects' biman-

ual movement coordination. The task was to play a series of nine key-

strokes either with one hand or simultaneously with both hands. Each

finger was assigned to one of five adjacent, white keys on the piano; no

lateral movements were required. We manipulated the complexity of

hand coordination by having subjects perform either with single hands

(left or right), mirror image movements for both hands, or different

movements for opposite hands. The tasks were presented as strings of

nine numbers, each number indicating which finger of a given hand

was to be used in performance. A display with the relevant task infor-

mation appeared on the computer screen and remained for subjects'

inspection during performance. Motor demands were identical across

tasks: the same series were used for the left and right hands; bimanual

tasks were generated by combining the single-hand tasks. Conditions

were tested in ascending order of complexity. Instructions encouraged

the subjects to play accurately and rapidly while maintaining a steady

tempo. The single-hand condition consisted of two series of keystrokes

for each hand; the two bimanual conditions involved playing two dif-

ferent series each. In addition to warm-up, each task consisted of an

initial block of 6 and a second block of 12 practice trials. During the

second block of practice trials, subjects received graphic feedback on

accuracy, speed, and the timing of single keystrokes (steadiness). Only

the data from the third block of 6 trials were used in the analysis.

Following the first experiment toward the end of Session 1, subjects

were introduced to the diary procedure. The introduction, recording

of daily activities during a 7-day period between Sessions 1 and 2, and

coding of activities were identical to the procedures described for

Study 1. Session 2 started with the debriefing for the diary procedure.

The musical performance task, following debriefing for the diary pro-

cedure in Session 2, required subjects to give three successive perfor-

mancesof the Prelude No. 1 in C-major ("Wohltemperiertes Klavier")

by J. S. Bach. Subjects were given up to 15 min of practice to work out

an interpretation and then attempted to replicate this interpretation

three times while being as consistent as possible across performances.

Musicians consider the piece to be technically very simple; at the same

time it leaves room for musical interpretation. All subjects were able to

perform the piece fluently except for the two amateurs, who were not

included in the analyses for this reason. Force and onset-offset times

for single keystrokes were recorded with the apparatus described previ-

ously; high-speed tape recordings were also generated for later evalua-

tion. Following the musical performance task, subjects completed a

paper-and-pencil version of the Digit-Symbol Substitution Test (DS), a

subtest of the WAIS that is considered a measure of general perceptuo-

motor speed. A two-choice reaction time task (CRT) required speeded

responses of pressing either one of two assigned keys on the piano

keyboard. Both tasks are often used to measure cognitive-motor

speed. Three finger tapping tasks involving their right, left, and alter-

nate forefingers, respectively, were used as measures of simple motor

efficiency. Following an auditory start signal subjects had to tap as fast

as they could for 15 s. Tasks were terminated by an auditory signal.

Results

Biographic Background

All experts had more than 14 years of playing experience;

amateurs had between 5 and 20 years of experience. Amateurs

382

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

had started with piano instruction at an average age of 9.9 years

and were reliably older than expert pianists, who started at 5.8

years of age, F(l, 22) = 7.00, p < .02. On average experts had

received 19.1 years of formal instruction from 4.7 teachers. In

comparison, the amateurs had received 9.9 years of instruction

and had studied with 3 different teachers on average. The dif-

ferences in years of formal instruction, F(\, 22) = 29.36, p <

.001, and number of teachers, F(l, 22) = 10.00, p < .01, were

significant. All of the expert subjects and 50% of the amateur

subjects were receiving formal instruction at the time of investi-

gation. All but one expert subject had participated in open

competitions (M = 3.6, SE = .73); only two amateur subjects

had ever participated in a competition at a local level. Whereas

amateur subjects were more likely to play at least one additional

instrument (M = 1.25, SE = .22), this was the exception for

expert pianists (M = .25, SE =.18); this difference was reliable,

F(\, 22) = 12.57, p < .01, and illustrates the experts' focus on

improvement on their main instrument.

Diaries

The experts spent a total of 56.75 hr on music-related activi-

ties during the diary week. In comparison, the amateurs spent

only 7.02 hr, F{\, 22) = 348, p < .001. As in Study 1, we analyzed

the amount and distribution of practice alone, the most rele-

vant activity for improvement in the skill, and also examined

data on sleep and leisure time.

Practice alone. During diary week, the experts spent 26.71

hr in solo practice at the piano; the amateurs spent 1.88 hr. This

difference was, of course, significant, F(l, 22) = 93.98, p < .001.

An analysis of the amount of practice as a function of weekday

had to be limited to the experts because the amateurs did not

practice at all on most days. No reliable difference between

weekdays was found. Figure 10 shows the distribution of prac-

tice activities across the time of the day averaged across week-

days.

To analyze the distribution of practice across time of the day,

we computed the amount of practice during five intervals as

described in Study 1. This analysis was also restricted to the

data on the expert pianists. It revealed no interaction between

weekday and interval and no main effect for weekday. The ef-

fect of interval did not reach significance, F(4, 44) = 2.57, p <

.052. An analysis of the length of practice sessions showed that

the experts practiced longer (87.90 min) than the amateurs

(46.00 min), F(l, 20) = 15.25, p < .001. These average durations

are probably overestimates as shorter breaks (< 15 min) between

consecutive sessions were probably not recorded in the diaries.

Sleep. The weekly amount of sleep did not differ for the

experts and the amateurs and averaged 56.86 hr per week. A

repeated measures ANOVA revealed a main effect of weekday,

F(6, 132) = 4.01, p < .002, which did not interact with skill

level. To locate the effect, we performed pairwise t tests con-

trasting the mean of each day with the means of other days. Six

out of 42 possible comparisons were significant, all involving

contrasts between a working day and either Saturday or Sunday.

These results indicate that both groups of pianists tended to

sleep longer during the weekend (M= 8.68 hr) than during the

working week (M= 7.91 hr). The average duration of napping

was only 0.63 hr per week and did not reliably differ between

the two groups.

Leisure. A repeated measures ANOVA was performed on

the amount of leisure time for each day during the diary week.

The amount of leisure time, 4.66 hr per day, did not differ for

experts and amateurs. As in Study 1, however, we obtained a

significant effect of weekday, F(6,132) = 11.04, p < .001. Eleven

out of 21 post hoc comparisons were significant, and 8 of these

involved contrasting a working day with a weekend day. Sub-

jects considerably increased their leisure time during the week-

end days (M = 6.22 hr) compared with the working week (M =

4.05 hr).

Retrospective Estimates of Practice During Musical

Development

To determine how good our subjects were at estimating how

long they practiced each week we compared the measures ob-

tained from the diaries with the estimate for the current year. A

repeated measures ANOVA with type of assessment as a within-

subjects factor yielded a main effect of type of assessment, F(l,

22) = 4.81, p < .05, and a main effect of skill level, F(l, 22) =

350, p < .001, but no interaction. Both experts and amateurs

overestimated their amount of practice during the diary week

by an average of 5.2 hr, in agreement with the results of Study 1.

Figure 11 shows the average amount of weekly practice as

estimated by amateur and expert subjects as a function of age

until age 20, the age of the youngest subject. Although expert

subjects show the same linear increase in the amount of prac-

tice that was found for the violinists, there is little change in

amateurs' training level after the mean starting age (9.9 years).

Following the procedure in Study 1, we calculated the average

amount of practice accumulated by a given age for each group

(see Figure 12). At the age of 18 the expert pianists had accumu-

lated 7,606 hr of practice, which is reliably different from the

1,606 hr of practice accumulated by the amateurs, F(\, 22) =

26.29, p < .001. The estimated amount of practice accumulated

by age 18 for the group of older expert pianists did not differ

from that of the younger experts, F(l, 22) = 1.74, p > .20. Simi-

larly, the accumulated amount of practice for the older ama-

THE ROLE OF DELIBERATE PRACTICE

383

teurs did not reliably differ from that of the younger amateurs,

F(l,22)=.83,p>.35.

Performance on Tasks Unrelated to Music

Performance in the two nonmusic tasks, the DS and the CRT

tasks, did not distinguish between experts and amateurs. Only

three subjects made errors on the DS. The mean digit-symbol

score was 69.0 and did not differ for the two groups, F(l, 22) =

1.18, p> .25.' The mean error rate in the CRT was 4.2% with no

differences between groups. The mean reaction time was 422

ms; again, differences between groups were not significant,

F(\, 22) = 1.09, p > .30. These results confirm the assumption

that domain-specific mechanisms, rather than more general

cognitive-motor abilities, are responsible for experts' superior

performance. The findings are in line with earlier proposals by

Lashley (1951) and Shaffer (1982), who suggested that inte-

grated complex representations ratherthan rapid serial process-

ing govern speed and fluency in a complex motor skill.

Music Performance: Validation of Differences in Piano

Performance

Two measures were derived from the musical performance

task: expert ratings on the musical quality of the interpretation

and the consistency of dynamic changes applied across the

three successive performances of the piece. Three expert raters

evaluated tape recordings of the second interpretation sepa-

rately for each subject. The evaluation consisted of seven scales

ranging from 0 to 10. The reliability of the rating instrument

was very high (Cronbach's alpha = .94 for both groups; a = .94

for amateurs, a = .79 for experts, on the basis of all 21 items).

Ratings were collapsed across scales and averaged for the three

raters. The average rating for expert pianists' performance was

6.4 (SE = .21) compared with 4.7 (SE = .42) for the amateur

group. The expert raters' overall evaluation of musical perfor-

mance was reliably higher for the expert pianists, F(l, 22) =

12.74, p<.01.

Thirty-two bars were used for statistical analyses of com-

puter recordings of keystrokes. The average force pianists ap-

plied to the 16 keystrokes in each bar was computed, and three

Pearson correlation coefficients corresponding to the similar-

ity between the three successive performances were calculated.

The average Pearson r was .695 for the amateurs and .866 for the

expert pianists. Single correlation coefficients were z trans-

formed and submitted to a repeated measures ANOVA. The

analysis yielded a main effect of skill level, F(l, 22) = 11.95, p <

.01, indicating that experts were more consistent in expressing

dynamic changes in terms of loudness than amateurs. This

main effect was not dependent on which two of the three perfor-

mances were compared.

Performance in Skill-Related Tasks

Tests of homogeneity of variances revealed that the mean

latencies between successive keystrokes (interstroke latencies)

were not normally distributed within skill groups. We therefore

analyzed the interstroke latencies for the simple tapping tasks

and the three conditions of the complex movement coordina-

tion experiment by log-transforming the latencies at the level of

single intervals.

Simple tapping tasks. Interstroke intervals from the three

tapping tasks were analyzed with a repeated measures ANOVA

with two orthogonal contrasts comparing left vs. right forefin-

ger tapping and single vs. alternate finger tapping. Both within-

subjects contrasts were significant, indicating that right-index

tapping was faster than left-index finger tapping, F(l, 22) =

21.63, p < .001, and alternate tapping was faster than single

forefinger tapping, F(l, 22) = 476, p < .001. The second con-

trast showed a reliable interaction with skill level, F(l, 22) =

8.19, p < .01, indicating that expert pianists' increase in speed

when the task allowed overlapping of movements between al-

ternate fingers was proportionally larger than for the amateurs

as shown in Figure 13. The overall effect of skill level was reli-

able, F(\, 22) = 26.63, p < .001; experts were faster on each of

these tasks than amateurs.

Complex movement coordination tasks. Performance on

single hand tasks was averaged for left and right hands, and the

mean log-interstroke latencies were calculated for the last block

of six criterion trials on each condition. A repeated measures

ANOVA was performed, contrasting single-hand performance

There are no available German norms for this specific version of

the digit-symbol substitution test. Two recent studies at the Max

Planck Institute for Human Development and Education in Berlin

show that the mean performance of groups of subjects with compara

ble age and educational background range between 59 and 66. Hence,

the performance of the two groups of expert and amateur pianists is

comparable although somewhat higher.

After log transformation the data approached a normal distribu

tion, where the mean and median coincide. The common procedure of

analyzing the median of observed latencies will hence give similar

results but entails somewhat less statistical power. An analysis based

on medians gave the exact same results as those reported below with

one exception. Namely, interaction between skill level and alternate

finger tapping was not reliable. The correlation between the medians

and the averages of the log-transformed latencies ranged from .94 to .99

with an average of .98.

384

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

with the two bimanual tasks and comparing the two bimanual

conditions, namely, mirror-image movements and different

movements in opposite hands. Both contrasts were significant

indicating that the complexity manipulation acted as pre-

dicted: Single-hand movements were faster than the average of

the two bimanual tasks, F(\, 22) = 92.34, p < .001, and differ-

ent movements in opposite hands were slower compared to

mirror-image movements in both hands, F(l, 22) = 53.39, p <

.001. The second contrast showed a reliable interaction with

skill level, F(l, 22) = 5.91, p < .05. This indicates that the

complexity of bimanual coordination impaired the amateurs'

performance more than the experts' performance. The main

effect of skill level was significant, F(l, 22) = 65.98, p < .001.

The main effect and the interaction are illustrated in Figure 14.

Relation Between Accumulated Practice and

Performance in Skill-Related Tasks

One premise of our theoretical framework is that perfor-

mance increases monotonically according to the power law

(J. R. Anderson, 1982; Newell & Rosenbloom, 1981). Accumu-

lated practice was thus log-transformed prior to analyses. A

hierarchical regression approach was used on all measures of

performance in skill-related tasks. The skill-level factor was

THE ROLE OF DELIBERATE PRACTICE

385

entered first. Then accumulated practice (log values) was en-

tered as a second step so that we could determine whether this

variable could predict within-group interindividual variation

that the skill factor could not capture. As a third step, the skill

level factor was removed from the regression equation so that

we could determine the degree to which accumulated practice

alone could account for task performance. Table 2 gives the R

(amount of variance explained) associated with the successive

implementation of the three regression models and the signifi-

cance levels for the relevant F tests.

The table illustrates two major findings. First, expert pian-

ists had a clear advantage in all measures of skill-related perfor-

mance; all R

s in the first row are significant. Second, accumu-

lated practice could account for the skill difference as well as

the skill factor could; there was no significant reduction in

variance explained when skill level was removed from the

equation for any of the variables (3rd row). Furthermore, accu-

mulated practice accounted for additional variance within

groups for the complex movement coordination tasks when

added to the skill-level factor. Inspection of the beta weights

revealed that the relation was in the predicted direction: Those

subjects who had practiced more did better in the experiments

even when skill level was statistically controlled for. Figure 15

illustrates the relation between accumulated amounts of prac-

tice and performance for the three conditions of the complex

movement coordination experiment.

To determine whether the additional variance accounted for

by accumulated practice was merely reflecting differences in

current practice intensity, we performed a separate set of con-

trol analyses. Current amount of practice (the number of hours

practiced during the diary week) was entered prior to accumu-

lated practice into the regression equations for each variable

listed in Table 2. The emerging pattern of results was as re-

ported before. This analysis shows that the effects of accumu-

Table 2

Performance in Skill-Related Tasks as Accounted for by Skill Level and Accumulated Amounts

of Practice in Study 2 ( R

s and Significance ofF Change)

Complex

movement coordination

Simple tapping

Single

hand

Mirror

image

Different

Right

Left

Alternate

movements

Skill level only

.55***

.43***

.47***

.74***

.67***

.66***

added wit

accumulate

ractice

.02 .02 .06

.05* .09**

08*

removed wit

skill leve

.04 .03 .01 .04 .01 .01

Accumulate

practice only

.53***

.42***

.52***

.75***

.73***

*p<.05.

**p <.01. ***p <.001.

386

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

2.4

lated practice remain predictive of current performance even

if the impact of current level of training is statistically con-

trolled for.

Another question in this context was whether general motor

ability would predict interindividual differences in task perfor-

mance once the effects of past practice were partialed out as

implied by Keele and Hawkins (1982). To test this claim, we

entered each of the simple tapping measures to the regression

equations for the three complex tasks as predicted by accumu-

lated practice. In no case did any of the three variables add

significant variance to the model. This analysis shows that the

interindividual differences in performance in simple motor

tasks do not predict performance differences in similar but

inherently more complex tasks once the effects of prior practice

are accounted for.

Summary of Results of Study 2

Consistent with our predictions, we found large differences

in the histories of deliberate practice for expert pianists and

amateurs. At no point during development did the two groups

accumulate comparable amounts of practice, or, as we would

infer, attain comparable levels of performance. The expert

pianists started on the average 4 years earlier than the ama-

teurs. Their average amount of practice increased each year

until it attained its current high level, whereas the amateurs

maintained their early levels until adulthood. The current

amount of practice assessed from the diaries is more than 10

times higher for the experts than for the amateurs. Even the

average length of their practice sessions differed. During the

diary week experts were fully engaged in music and spent close

to 60 hr on music-related activities. Their practice was evenly

distributed across the entire week, and the length of practice

sessions was limited, in accord with our theoretical expecta-

tions. We found no differences in the weekly allocation of rest-

ful activities, such as sleep and leisure, between the expert pian-

ists and the amateurs, who also were students in domains other

than music. For both groups the amount of sleep and leisure

increased during the weekend, the pattern normally seen in

studies of samples of the general population (Robinson et al.,

1972). It is difficult to assess the influence of the musical in-

strument on the differences between the expert pianists and

the two best groups of expert violinists. In the next section we

discuss differences in starting ages between the two groups.

However, in most important respects the pattern of results is

remarkably consistent for the expert pianists and violinists.

We initially proposed three levels of investigation to decom-

pose the complex skill of playing the piano: efficiency of periph-

eral motor functions, coordination of complex bimanual move-

ments, and the ability to consistently vary movement parame-

ters in expressive musical performance. Findings from all

experimental tasks designed to test these components were in

line with our predictions: The data revealed considerable dif-

ferences between experts and amateurs. The differences be-

tween skill groups increased with the hypothesized level of task

complexity in the simple finger tapping tasks as well as in the

more complex movement coordination tasks. Clearly experts

can overcome the processing constraints in the more difficult

task conditions. These constraints seem to arise mostly from

requirements for bimanual coordination and have been docu-

mented for untrained subjects in earlier studies (Kelso, South-

ard, & Goodman, 1979; Klapp, 1979). Shaffer (1981) demon-

strated that expert pianists show superior abilities for indepen-

dent timing of movements in opposite hands. Our results are

also in line with findings for a skill that in several ways is re-

lated to playing the piano, namely typing. A recurrent finding

has been that expert typists' speed advantage is most pro-

nounced for rapidly alternating keystrokes between hands

(Gentner, 1988; Salthouse, 1984; Shaffer, 1976), whereas the dif-

ferences for repetitive movements of the same finger are nor-

mally the smallest.

The skill advantage in our study was limited to those tasks

THE ROLE OF DELIBERATE PRACTICE

387

that presumably reflect components of skilled performance; no

skill differences were apparent in the two far transfer tasks.

Interindividual differences in skill-related tasks could be pre-

dicted from accumulated amounts of practice, as predicted,

even when current levels of training were statistically con-

trolled for. Predictions that were based on the power law model

of practice were as good as those based on the skill level factor;

predictability was even reliably better for the complex move-

ment coordination tasks that were designed to maximize perfor-

mance differences supposedly underlying the skill.

Although our study does not directly disconfirm the asser-

tions that general cognitive-motor abilities account for perfor-

mance in a complex skill (e.g., Keele & Hawkins, 1982), it is

hard to see how our findings could be reconciled with those

accounts. The absence of skill effects in the two far transfer

tasks is not in line with these explanations. Furthermore, the

regression analyses reported here support the notion that skills

(even simple tapping skills) are gradually acquired rather than

inherited as stable cognitive-motor dispositions.

The Framework Applied to Several Domains of

Expertise

The central thesis of our framework is that expert perfor-

mance is the result of an extended process of skill acquisition

mediated by large, but not excessive daily amounts of deliberate

practice. In the domain of music, we showed that individual

differences in adult levels of performance were correlated with

the past and current amount of deliberate practice at a given

age, in particular the age of 18, when performers in music are

normally selected for higher levels of professional training. Be-

cause our methodology for assessing the current and past

amounts of deliberate practice is new, we further explicate the

relation between performance and deliberate practice by con-

sidering research findings in music and other domains of ex-

pertise.

Our framework predicts a monotonic relation between the

current level of performance and the accumulated amount of

deliberate practice for individuals attaining expert perfor-

mance. The general shape of this relation is illustrated by the

solid line in Figure 16. It is relatively rare that domains of exper-

tise have a univariate performance variable that quantifies the

performance for individuals at different ages and levels of per-

formance. The best examples are individual track and field

events in sports, for which the performance of any individual

can be measured. Particularly in sports, but in other domains as

well, developmental and maturational factors are known to in-

fluence performance as a function of age. For example, age-re-

lated changes in height may directly or indirectly influence

performance in certain sports. For these reasons in virtually all

domains individuals are grouped by age for external evaluation

and competitions. Consequently, many studies report perfor-

mance as a function of age. If performance is graphed as a

function of age, where the first data point corresponds to an

individual's introduction to the domain and start of deliberate

practice, we expect a monotonic relation similar to the solid

line in Figure 16, although the exact functional form of the

curve is not important.

To evaluate acquired musical skills, J. G. Watkins (1942) de-

signed a test to assess the level of performance of a musical

piece by 151 cornet players who had had from 1 to 10 years of

prior practice. Music performance was related to the number of

years of practice by a functional form very similar to the solid

line in Figure 16. Longitudinal studies of elite performers

found that their recorded performance at younger ages shows

monotonic improvement even well after the age of 18 when

physical maturation is completed. Curves for the personal best

performance on an event as a function of age and training for

elite performers (see Ericsson, 1990, for some examples) have

roughly the shape shown by the solid line in Figure 16 until a

contestant attains the highest performance of his or her career.

The rating system in chess has properties of an interval scale,

and Elo (1978) found that the earlier chess ratings increased in a

similar manner as a function of age well through their twenties

for three groups of elite chess players.

When we consider the evidence for the 10-year rule of prepa-

ration to attain international-level performance, even when in-

dividuals started during adolescence and adulthood, a rather

continuous acquisition of expert performance is implicated.

Evidence for the accumulated effects of deliberate practice on

expert performance is clearer when we examine mediating skill

components, such as increases in amount of accessible knowl-

edge, where the acquisition process is well established in labora-

tory studies. Differences in expert performance have been suc-

cessfully related to tests measuring the amount of relevant

knowledge and procedures in chess (Pfau & Murphy, 1988),

mathematics (Webb, 1975), and sports (French & Thomas,

1987). The organization and accessibility of knowledge has also

been shown to distinguish individuals at different levels of ex-

pertise in physics (Chi, Glaser, & Rees, 1982), medicine (Felto-

vich, Johnson, Moller, & Swanson, 1984; P. E. Johnson et al.,

1981), and social science (Voss, Greene, Post, & Penner, 1983).

Unlike the rapid decay of acquired knowledge seen in labora-

tory studies, repeated application and use of knowledge over

extended periods leads to remarkably good retention of the

388

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

knowledge even after years or decades of disuse. Bahrick and

Hall (1991) found considerable retention of knowledge of math-

ematics for content from a successive sequence of courses with

the exception of the most advanced mathematics course taken.

Similarly, once an individual has acquired a reasonably high

level of skill, it is possible for that individual to attain an above-

average performance or even regain the original performance

after a brief period of retraining. A moderate level of acquired

skill in typing (Baddeley & Longman, 1978; Hill, 1934,1957;

Hill, Rejall, & Thorndike, 1913), language (Bahrick, 1984), and

other domains (Farr, 1987) appears to decay slowly and can be

rapidly reacquired.

The demonstrations of retained skill without recent practice

as well as of regaining a considerable level of skill with limited

current practice are relevant to our framework for a couple of

reasons. First, such demonstrations might appear to show a

complete dissociation of current practice and performance.

Given that acquired skill resulting from prior accumulated

practice cannot be observed, it could easily be incorrectly attrib-

uted to native talent. Second, the relatively small amount of

practice required to maintain or regain a previously acquired

level of nonelite performance is quite different from the mas-

sive amount of practice required originally to attain that level or

improve even more. Furthermore, elite performers rarely experi-

ence problems from long periods of inactivity because once

they take up systematic practice they continue practicing at a

uniformly high level, and we assume that the amount of deliber-

ate practice necessary to specifically maintain earlier attained

levels of performance is negligible for active young experts.

Our framework postulates that individual differences in per-

formance at a given age are a function of acquired characteris-

tics, which in turn are directly related to the accumulated

amounts of deliberate practice. Given the earlier reviewed evi-

dence for the stability of daily and weekly amounts of practice,

it is possible to approximate the accumulated amount of prac-

tice on the basis of weekly estimates. There are two sources of

individual differences. First is the number of years of deliberate

practice, which is a linear function of starting age. In the Gen-

eral Discussion we discuss the possibility that assessed talent

prior to practice is the cause for initiating practice early. Sec-

ond, individual differences in the weekly amount of practice at

a given time will influence the rate of increase of accumulated

practice and the current level of performance. Current perfor-

mance and current level of practice are determined concur-

rently and the direction of causality cannot be determined on

temporal grounds. In the following review of evidence on

weekly amounts of practice, we discuss additional evidence on

the direction of causality.

Relation Between Starting Age and Performance

During childhood and adolescence the performance of an

individual is evaluated by comparison to those of other individ-

uals of the same age. An individual starting at an earlier age

would have accumulated more deliberate practice and thus

have acquired a higher level of performance. An individual ex-

hibiting a higher performance at any age would be more likely

to be given resources and support by the environment. The

dashed line in Figure 16 illustrates performance as a function of

age for an individual who starts practicing later in life than the

individual represented by the solid line. In this ideal case, the

dashed line is simply shifted to the right, which gives the indi-

vidual with the earlier starting age a higher performance level at

all ages. Even in a more realistic case, where the performance

level of individuals starting later would initially increase faster,

the advantage of an early start would remain. In many different

domains elite performers tend to start deliberate practice and

instruction at remarkably young ages. In this section we con-

sider the starting ages of music performers, athletes, and chess

players. Information about world-class and eminent performers

will also be included as their development is assumed to match

or surpass the top-level expert performers.

A discussion of music performers requires a separate review

for different instruments. Consistent with the observation that

it is more difficult fora child to play a normal-sized violin than

a piano, we found that our four groups of expert violinists were

older when they started than were the expert pianists, F(\ , 40)

= 9.60, p<. 01. This comparison is shown in Table 3. Although

we found no statistically reliable differences among the starting

ages of the different groups of adult violinists, these violinists

started almost 3 years later than a group of the best solo violin-

ists of the 20th century (Heizmann, Krampe, & Ericsson,

1993), F(1, 41) = 18.88. p < .001. Only those 13 violinists who

had had a solo career for more than 20 years and were men-

tioned by both Roth (1982, 1987) and Schwarz (1983), three

main reference books, as internationally famous violinists born

in the 20th century were included in this group of outstanding

performers. Expert pianists in Study 2 started instruction at

nearly the same age as the age given by Sosniak (1985) for pian-

ists who win international competitions, which is similar to

internationally famous pianists from the 20th century (Heiz-

mann et al, 1993). Expert pianists in their fifties and sixties

(Krampe, 199!) had a starting age of 7.8 years, which was con-

siderably older than for the young experts in Study 2 and the

famous pianists. The starting ages for amateur pianists are reli-

ably older, as we reported in Study 2. It appears necessary for

professional musicians to start earlier than most of the ama-

teurs in the same domain. The large sample of elite music per-

formers studied by Manturzewska (1990) contained no individ-

ual who had started later than age nine.

In sports, the time at which an individual first engages in the

activity is much less closely linked to the start of deliberate

practice than to the start of competition in an event after the

individual joins a team. Table 3 summarizes data on starting

ages for athletes at different levels of performance in swim-

ming, gymnastics, running, and tennis.

Chess differs from music and sports in that chess is not nor-

mally studied under the close supervision of professional

teachers and coaches who direct daily practice activities. Even

in chess, however, some critical events and indicators enable us

to assess players' early exposure and occupation with the game.

To be able to play chess, a beginner must receive an explanation

of the rules, and a chess board has to be available. Hence the

starting age for playing chess is fairly distinct and can be easily

reported, especially by chess players. Krogius (1976) presented

biographical data on world-famous chess masters born in the

19th and 20th centuries. The oldest starting age among Kro-

gius' grand masters was 17. For chess players born in this cen-

THE ROLE OF DELIBERATE PRACTICE

389

tury, the oldest starting age is 14, and the mean starting age is 9

years. We found that in Krogius' data, the starting age is closely

correlated, r(38) = 0.48, p < .001, with the age of players' first

achievement of an international level of performance. Accord-

ing to Mayr (1989), a small sample of contemporary grand mas-

ters reported starting at about 7 years of age, a finding that

suggests a historical trend toward younger starting ages. The

starting age for a larger sample of chess masters was 10.5 years

of age. The age at which contemporary grand masters joined a

chess club is reliably younger than the age for contemporary

national-level chess masters in Mayr's sample (Ericsson, Tesch-

Romer, & Krampe, 1990).

Consistent with our hypothesis, we find that the higher the

level of attained elite performance, the earlier the age of first

exposure as well as the age of starting deliberate practice. In

some domains such as music and ballet, it is generally found

that elite performers have started well before the age when most

children first gain access to training.

Weekly Amount of Practice and Performance During the

Development of Elite Performance

Once individuals have started with deliberate practice, addi-

tional differences in accumulated practice can be due to indi-

vidual differences in the weekly amount of deliberate practice

at the same ages. The dashed line in Figure 16 illustrates a case

with a higher level of weekly practice, which would give an

individual a uniform advantage compared with the individual

with the same starting age but with less weekly practice (dotted

line). This case is similar to the differences in weekly practice

intensity between the four groups of violinists in Study 1.

In our review of practice in the domain of music, we found

evidence for the claim that deliberate practice is a specific type

of music-related activity, which is judged to be most relevant for

improvement of music performance, effortful, and less inher-

ently enjoyable than leisure and several other music-related ac-

tivities. Individual differences in the amount of deliberate prac-

tice in music at the same ages were found to correlate with

current and future music performance, even sometimes in the

absence of reliable differences in the overall amount of time

spent on music-related activities. Given that the distinction be-

tween deliberate practice and other domain-related activities is

new, it is difficult to find available data relating performance

and weekly amounts of deliberate practice. We review available

evidence on indicators of deliberate practice in sports, where

coaches supervise training and also in chess, where individuals

are assumed to acquire their skill without explicit guidance.

On the basis of interviews and questionnaires, future elite

performers have been found to spend a large amount of time

per week on their domain even at a young age: 20 hr per week

by tennis players around age 13 (Monsaas, 1985) and 24-30 hr

per week by swimmers around age 11 (Kalinowski, 1985).

Given that these childrens' and adolescents' activities are for

the most part supervised by coaches, it can be inferred that a

significant portion of this time is spent in deliberate practice.

Better estimates of current levels of practice have been obtained

by Kaminski et al. (1984) who used a diary procedure to assess

the duration of actual practice for national-level swimmers, ice-

skaters, and gymnasts at ages 15-16. These athletes practiced

about 16 hr per week, almost 3 hr more than the athletes below

the national level practiced. These pure estimates of practice

cannot be directly compared with the retrospective estimates

for the international-level athletes (Kalinowski, 1985; Mon-

saas, 1985), but they appear to be considerably lower. On the

basis of the questionnaire responses from a large sample of

male runners, 17-18 years old, Sack (1975) estimated the fre-

quency of training during a week for runners at different levels

of performance. Runners at the national level trained 4.9 times

per week; runners at regional and local levels trained 4.2 and

3.2 times per week, respectively. Apart from the number of

participations at national championships, the best predictor of

the subjects' best running performance was the frequency of

training (r = .56). Questionnaire items referring to motivation

(e.g., "regular training" and "training during holidays") were

reliably correlated with both frequency of practice and perfor-

mance. The performance of adult marathon runners in a race

can be predicted with high accuracy from the regularity and

amount of practice during the 9 weeks preceding the race (Ha-

gan, Smith, & Gettman, 1981). The length of training runs and

the total distance covered per week accounted for nearly half of

the variance in actual running times on the marathon. Even

better evidence for the relation between performance and

390

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

amount of practice comes from recommended training sched-

ules for different levels of competitive runners (Glover &

Schuder, 1988). Championship competitors not only take more

time practicing and cover longer running distances than ad-

vanced and basic competitors, but they spend proportionally

more time on training directed at improving endurance and

speed, such as interval training and fartlek. An analysis of the

training schedules of the world's best long-distance runners

shows that they uniformly put a major emphasis on speed work

(Noakes, 1991), which is typically completely absent in the

training of recreational runners. A recent interview study

(Sachs, 1991) of conditions inducing the enjoyable state called

"runners' high" showed the importance of a comfortable pace

during an extended run and the absence of any strain to run

fast, which seems to preclude deliberate practice.

Unfortunately, we did not find any systematic data on the

amount of time elite chess players spend playing and studying

chess. There are, however, some unique data available about

improved competence in chess as a function of age (Elo, 1978).

With the Elo Rating System, it is possible to assess the chess

skills of young chess players with the same interval scale used

for adults. By analyzing the development of chess skills in many

individuals who reached world class, international level, and

national level, Elo (1978) found that at 11-12 years of age, dif-

ferences in chess playing ability were relatively small. At that

age, all three groups of subjects played at the level of average

adult chess players. Large improvements in ability were ob-

served for the players during adolescence (12-18 years of age).

From the ages of 18-22, improvements started leveling off and

differences in ability between the three groups remained rela-

tively unchanged. These results are unique within the three

domains considered in this article because musical perfor-

mance is not rated on an age-independent scale, and physical

growth during adolescence seriously confounds available mea-

sures of performance in sports.

Even less information is available on the way full-time chess

players allocate their time to chess-related activities. Charness

(1991) estimates that the actual time spent playing chess games

at tournaments, chess clubs, and private games constitutes only

a fraction of the time available to chess players and that they

give more time to individual study and analysis of chess posi-

tions and published chess games. In informal interviews, chess

masters report spending around 4 hr a day analyzing published

chess games of master-level players. Selecting the next moves in

such games provides an informative learning situation in which

players compare their own moves against those selected in an

actual game. A failure to select the move made by the chess

masters forces the chess players to analyze the chess position

more carefully to uncover the reasons for that move selection.

There exists also a large body of chess literature in which world-

class chess players explicitly comment on their games and ency-

clopedias documenting the accumulated wisdom on various

types of chess openings and middle-game tactics and strategies.

An examination of biographies of world-class chess players

(Karpov & Roshal, 1980; Korchnoi, 1978) shows, contrary to

common belief that chess players develop their chess skills inde-

pendently, that these elite players have worked closely with indi-

viduals (other more advanced players, often chess masters) who

explicitly taught them about chess and introduced them to the

literature on chess. Of particular interest are Bobby Fischer and

Judit Polgar, who attained their international grand master sta-

tus at the youngest recorded age, namely age 15. Bobby Fischer

learned the rules of chess at age 6 and in the same year he

started studying his first book of chess games (F. Brady, 1973).

As a result of his mother's initiative, at age 7 Bobby got in touch

with the president of the Brooklyn Chess Club, who tutored

Bobby on a weekly schedule for several years and actively sup-

ported Bobby's chess career. At age 12 Bobby joined the Man-

hattan Chess Club, which was one of the strongest in the world.

Around that time he started close interactions with the strong

chess master Jack Collins several times a week and got free

access to Collins' outstanding library of chess books. From that

point Bobby started collecting chess books, and in 1973 he had

about 400 books and thousands of magazines and journals (F

Brady, 1973). According to Brady (1973), Bobby Fischer be-

came the best educated chess theoretician in modern times.

Judit Polgar was tutored in chess by her father from age 4 (J.

Radford, 1990) or, at least, age 5 (McFadden, 1992) and care-

fully coached by her father. Judit did not attend regular school

and was allowed to spend all the time with her parents, who

were both teachers.

Consistent with our framework, we find that elite performers

spend much time on deliberate practice and, in those cases in

which amount of weekly deliberate practice has been recorded,

high level of performance is associated with higher levels of

deliberate practice at the same age. Another striking, but not

surprising, finding is that the amount of weekly practice for

individuals maintaining regular practice increases with age, ac-

cumulated practice, and performance. Given the early starting

ages and the high level of practice of the expert performers the

available data do not allow an analysis of the independent and

interactional effects of those variables. Furthermore, the struc-

ture of training programs in virtually any domain adapts the

deliberate practice activities to suit the level of current perfor-

mance. Increased complexity and proficiency of acquired skills

and characteristics leads to increased performance and allows

for engagement in more challenging deliberate practice activi-

ties for a longer period of time. This would be particularly clear

for domains with endurance activities, such as long-distance

running. In our framework we expect that increased level of

acquired skill and performance would increase the maximal

level of deliberate practice that can be sustained over extended

periods of time without exhaustion.

In our framework accumulated deliberate practice causes ac-

quired skill and characteristics, which in turn cause perfor-

mance, and some of these characteristics increase the maximal

amounts of possible practice. It is, of course, possible that non-

acquired factors, such as innate talent, might influence perfor-

mance directly. A performance advantage resulting from such

factors can allow individuals, essentially by definition, to com-

plete the same activities (including deliberate practice) for

longer times with the same amount of effort. Although this

mechanism provides an account for individual differences in

work-related activities, where the goal is to maximize the

amount produced, we believe that it cannot be extended to

deliberate practice for the following reasons: The goal of deliber-

ate practice is not "doing more of the same." Rather, it involves

engaging with full concentration in a special activity to improve

THE ROLE OF DELIBERATE PRACTICE

391

one's performance. As deliberate practice is not inherently en-

joyable, there doesn't seem to be any reason for engaging in it or

prolonging its duration unless the individuals and their

teachers believe that their performance improves as a result.

Many other domain-related activities are judged to more enjoy-

able than deliberate practice and they should be preferred.

Hence, there doesn't seem to be any reason for engaging in

deliberate practice, and especially prolonging its duration, un-

less the individuals and their teachers believe that their perfor-

mance improves as a result.

Further evidence against the hypothesis that higher levels of

performance cause an elevated level of deliberate practice is

found for adult elite performers. The general level of deliberate

practice has been increased in many domains in the recent

past. For example, the training distances in swimming were

almost doubled in preparation for Olympic Games in 1972 (Ka-

linowski, 1985). The steady improvement of world records in

sports is generally recognized to reflect more practice and, in

particular, the faster improvement of world records for women

is believed to be due to disproportionate increase in the levels

of training for women (Wells, 1991). In Study 1 we found differ-

ences in accumulated practice but no differences in the current

levels of deliberate practice for the best and the good expert

violinists. The daily amount of around 4 hr of deliberate prac-

tice was also found for the expert pianists, raising the possibil-

ity of a more general limit on the maximal amount of deliberate

practice that can be sustained over extended time without ex-

haustion.

Maximal Levels of Deliberate Practice Sustained Over

Extended Periods

According to our framework, elite performers attempt to

maximize the improvement of performance all through their

development and, thus, should reach in adulthood the highest

stable levels of deliberate practice that they can sustain without

exhaustion. During adolescence, the daily lives of future elite

performers are quite constrained by school activities. In spite of

this, Kaminski et al. (1984) found that young elite performers in

music and various types of sports, such as gymnastics, swim-

ming, and ice-skating, spent more than 15 hr on weekly prac-

tice. Furthermore, this amount did not differ systematically

across domains. When expert performers make a full-time

commitment to the domain, our studies showed that they

spend between 50 and 60 hr per week on domain-related activi-

ties. Less than half of that time (about 25 hr per week) is spent

on deliberate practice, and this time is distributed across the

entire week in practice sessions of limited duration. Our analy-

ses of rest and relaxation were consistent with our claim that

these individuals had attained a level of deliberate practice lim-

ited not by available time but by available resources for effortful

practice.

A similar pattern holds true for professional athletes. Elite

long-distance runners usually run twice a day and cover dis-

tances from 65 to 140 miles every week of the year (Hagan et al.,

1981; Wallingford, 1975). From published reports in the maga-

zine Runner's World on the weekly practice schedules of profes-

sional long-distance runners who are in complete control of the

duration and distribution of practice, it is clear that the vast

majority of runners practice every day except for days during

the weekend with competitions. A normal day of practice con-

sists of a session before lunch and a more strenuous session in

the afternoon. The duration of a training session is about 45-90

min and the daily total of deliberate practice amounts to 2-3 hr.

The total time including preparation, warm-up, massage, and

so forth, is considerably longer. Similar estimates are reported

for other types of sports, such as swimming (Reilly, 1990b) and

cycling (Burke, Faria, & White, 1990). Athletes' pursuit of most

other types of sports is characterized by maximal efforts to

train without inducing exhaustion and burnout (Reilly &

Secher, 1990). Similar to musicians, the amount of deliberate

practice is not limited by available time; professional athletes

spend their "free" time on recuperation and relaxing activities.

Olympic athletes sleep for close to 8 hr and in addition take a

half-hour nap each day (Coleman, 1986). Many elite runners

take a nap between daily workouts (Glover & Schuder, 1988).

The complete focus on a single domain by elite performers in

music and sports is further evidence that their efforts to reach

their highest performance in that domain are maximal.

Studies of international-level performers have included ar-

tists and scientists as well as athletes and musicians. The studies

reported in a book edited by Bloom (1985a) show several clear

parallels between the development of artists and scientists on

the one hand and that of athletes and musicians on the other.

\fears of intensive preparation under the supervision of a mas-

ter invariably precede the attainment of international recogni-

tion. Consistent with the data on athletes and musicians, emi-

nent scientists are completely absorbed in their vocation so "as

to seriously limit all other activity" (Roe, 1953, p. 49). The de-

gree of commitment has been quantified in a couple of sources

(Bruner, 1983; J. R. Hayes, 1981) to suggest that scientists must

work 80 hr per week for an extended time to have a chance of

reaching an international level in their field. Although our theo-

retical framework supports the full commitment to the domain

it takes issue with the implication that one should maximize

the number of hours of any domain-related activity. Instead we

suggest that one should identify those activities that are most

likely to result in the desired achievements.

In science an eminent achievement nearly always corre-

sponds to a new theory or idea presented in the written publica-

tion of a persuasive argument. The deliberate activities that are

necessary for producing such a rare result consist of focused

and extended work developing and refining generated theoreti-

cal solutions to selected general problems. We believe that dur-

ing the process of writing scientists develop and externalize

their arguments. The written products can be successively criti-

cized and improved by the scientists themselves, even after long

delays, and also easily shared with other scientists for evaluation

and comments. The writing of expert authors on new topics is

deliberate and constitutes an extended knowledge-transform-

ing process, quite unlike the less effortful knowledge-telling

approach used by novice writers (Scardemalia & Bereiter,

1991). In support of the importance of writing as an activity,

Simonton (1988) found that eminent scientists produce a much

larger number of publications than other scientists. It is clear

from biographies of famous scientists that the time the individ-

ual spends thinking, mostly in the context of writing papers

and books, appears to be the most relevant as well as demand-

392

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

ing activity. Biographies report that famous scientists such as C.

Darwin, (E Darwin, 1888), Pavlov (Babkin, 1949), Hans Selye

(Selye, 1964), and Skinner (Skinner, 1983) adhered to a rigid

daily schedule where the first major activity of each morning

involved writing for a couple of hours. In a large questionnaire

study of science and engineering faculty, Kellogg (1986) found

that writing on articles occurred most frequently before lunch

and that limiting writing sessions to a duration of 1-2 hr was

related to higher reported productivity. Many scientists in-

volved in laboratory studies, teaching, and administration

must cope with external constraints on their time that may

partially determine how they schedule writing and thinking. In

this regard, it is particularly interesting to examine the way in

which famous authors allocate their time. These authors often

retreat when they are ready to write a book and make writing

their sole purpose. Almost without exception, they tend to

schedule 3-4 hr of writing every morning and to spend the rest

of the day on walking, correspondence, napping, and other less

demanding activities (Cowley, 1959; Plimpton, 1977).

Further evidence that elite performers try to maximize the

effectiveness of their deliberate activities is found in their prefer-

ence for engaging in them at a certain time of day. The preferred

time of day for deliberate activities differs across domains. Sci-

entists and authors consistently chose to use mornings for de-

manding writing, and athletes prefer afternoons for their most

strenuous practice sessions. Research on the effects of the time

of day (Folkard & Monk, 1985) shows that simple perceptual-

motor performance is enhanced in the afternoon and early eve-

ning, whereas intellectually demanding activities are enhanced

in the morning. Systematic studies confirm that performance

of elite athletes is reliably higher in the afternoon and evening

than in the morning (Winget, DeRoshia, & Holley, 1985).

Across several different types of domains, elite performers

are found to engage in similarly high levels of selected activities,

such as deliberate practice. The complete focus on the domain

provides most of these individuals with much available time,

yet the time for deliberate practice occupies only a fraction of

that time, with clear preferences about the best time of day. The

amount of time they spend on practice and other highly rele-

vant activities appears to be limited by how long the demand-

ing activity can be continued with sustained benefits rather

than by the available time.

An Account of Individual Differences in Elite

Performance in Terms of Deliberate Practice

In our framework we distinguish between two types of elite

performance: expert and eminent performance. Expert perfor-

mance reflects the mastery of the available knowledge or

current performance standards and relates to skills that master

teachers and coaches know how to train. Eminent performance

requires that the individual go beyond the available knowledge

in the domain to produce a unique contribution to the domain,

hence it is, by definition, not directly instructable. Our frame-

work proposes that the probability of making eminent contri-

butions is related to the amount of deliberate efforts directed

toward that goal.

Our framework makes stronger claims for the acquisition of

expert performance. We argue that expertise and expert perfor-

mance are the result of extensive engagement in relevant prac-

tice activities supervised by teachers and coaches and that indi-

vidual differences in ultimate performance can largely be ac-

counted for by differential amounts of past and current levels of

practice. Across many domains of expertise, a remarkably con-

sistent pattern emerges: The best individuals start practice at

earlier ages and maintain a higher level of daily practice. More-

over, estimates indicate that at any given age the best individ-

uals in quite different domains, such as sports and music, spend

similar amounts of time on deliberate practice. In virtually all

domains, there is evidence that the most important activity—

practice, thinking, or writing—requires considerable effort and

is scheduled for a fixed period during the day. For those excep-

tional individuals who sustain this regular activity for months

and years, its duration is limited to 2-4 h a day, which is a

fraction of their time awake.

Contrary to the popular "talent" view that asserts that differ-

ences in practice and experience cannot account for differences

in expert performance, we have shown that the amount of a

specific type of activity (deliberate practice) is consistently

correlated with a wide range of performance including expert-

level performance, when appropriate developmental differ-

ences (age) are controlled. Because of the high costs to the indi-

viduals and their environments of engaging in high levels of

deliberate practice and the overlap in characteristics of deliber-

ate practice and other known effective training situations, one

can infer that high levels of deliberate practice are necessary to

attain expert level performance. Our theoretical framework can

also provide a sufficient account of the major facts about the

nature and scarcity of exceptional performance. Our account

does not depend on scarcity of innate ability (talent) and hence

agrees better with the earlier reviewed findings of poor predict-

ability of final performance by ability tests.

We attribute the dramatic differences in performance be-

tween experts and amateurs-novices to similarly large differ-

ences in the recorded amounts of deliberate practice. Further-

more, we can account for stable individual differences in perfor-

mance among individuals actively involved in deliberate

practice with reference to the monotonic relation between ac-

cumulated amount of deliberate practice and current level of

performance. The individuals who start early and practice at

the higher levels will have a higher level of performance

throughout development (the solid line in Figure 16) than those

who practice equally hard but start later (line with long dashes).

The differences in performance between subjects with the

same starting age but differing levels of practice are shown in

Figure 16, where the line with long dashes shows the perfor-

mance associated with a high level of practice and the dotted

line a lower level of practice.

Figure 16 illustrates how our framework can account for

many common observations about skill acquisition and stable

individual differences in performance. Individuals with a later

starting age for deliberate practice will experience rapid initial

improvements and may feel that they will in a few years attain

the level of individuals with earlier starting ages and thus higher

performance at comparable ages. However, because the rate of

improvements with practice decreases and becomes less percep-

tible, the difference between the two groups remains distinct,

and an attribution of greater talent for the group with earlier

THE ROLE OF DELIBERATE PRACTICE

393

starting ages is natural. In the current system with age-matched

evaluation of performance, it is impossible for an individual

with less accumulated practice at some age to catch up with the

best individuals, who have started earlier and maintain maxi-

mal levels of deliberate practice not leading to exhaustion. As

noted earlier, the amount of possible practice appears to slowly

increase with accumulated practice and skill. Hence, individ-

uals intent on catching up may suddenly increase the amount of

deliberate practice to the level or even above the level of the best

performers. Within months these individuals are likely to en-

counter overuse injuries and exhaustion and may terminate

their engagement in the domain convinced that the best per-

formers are qualitatively different. Furthermore, the difference

in accumulated deliberate practice in late adolescence for the

good and best violinists is remarkably large and to eliminate

this difference the good violinists would have to practice an

additional 5 h per week beyond their current optimal level of

weekly practice for more than 8 full years.

The problem of overcoming differences in skill resulting

from accumulated practice is further amplified by the continu-

ous selection of individuals because of the costs associated with

the maintenance of deliberate practice. In all domains there is

only a small number of positions in which individuals can freely

continue their efforts to attain eminent performance without

severe occupational constraints. Prior to that, the best training

environments with master teachers and coaches carefully select

the individuals with the best performance in late adolescence.

Institutions providing grants and master teachers have strong

restrictions on the maximum age of applicants. From the start

of training, the individual and his or her teachers and parents

constantly monitor and compare the current performance to

that of other individuals of the same age in the domain to assess

whether the costs in time, effort, and money associated with

sustaining high levels of deliberate practice are warranted. A

high level of performance, whether it is due to acquired skill or

to innate talent, will always be the best predictor of future

performance and will therefore attract motivational support

and necessary resources. The majority of individuals in the

domain are not provided these resources because of their lower

current performance at the relevant ages with lost opportuni-

ties for further development.

In addition, our theoretical framework can easily account for

changing levels of performance in different historical times

and in different cultures by corresponding differences in the

encouragement and availability of deliberate practice. Wells

(1991) attributed the big differences in athletic performance

between men and women, which are currently decreasing as a

function of changing sex-role expectations, to differential "op-

portunities for participation at an early age and the availability

of expert coaching" (p. 49).

In summary, our framework can account for a wider range of

empirical characteristics of exceptional performance than the

talent view. Although we are reluctant to accept individual dif-

ferences in innate abilities (talent) and any important role of

these differences in determining expert performance, we do

not rule out the importance of individual differences in gen-

eral. In fact, within our framework we would expect that several

"personality" factors, such as individual differences in activity

levels and emotionality may differentially predispose individ-

uals toward deliberate practice as well as allow these individ-

uals to sustain very high levels of it for extended periods. We

now turn toward a reevaluation of the evidence linking expert

performance and innate abilities and characteristics reviewed

in the introduction. Once individuals have started deliberate

practice, it is virtually impossible to distinguish the role of natu-

ral ability (innate talent) from that of acquired characteristics

and skill in their current level of performance. This is particu-

larly true as the effects of extended practice, especially at young

ages, are much more far reaching than commonly believed pos-

sible. In the General Discussion we review evidence on the

possibility that early signs of natural ability (talent) are the

cause of especially early start of practice, as well as the reverse

possibility that characteristics assumed to reflect innate talent

are the result of deliberate practice.

General Discussion

In a couple of respects our findings and those from the litera-

ture we reviewed are consistent with two of the three factors

Galton (1869/1979) thought necessary for attaining eminent

performance. The necessity for 10 years of preparation is clearly

consistent with Galton's requirement of motivation and perse-

verance. The quantified role of deliberate practice corresponds

nicely with Galton's prerequisite of "adequate power of doing a

great deal of very laborious work" (p. 37). Although both of

these factors could be plausible loci for heritable differences,

Galton and subsequent researchers in genetics have empha-

sized that a third factor, namely, innate ability, is the major

source of heritable differences that determine eminent perfor-

mance.

The best information about the innate attributes characteriz-

ing the best performers can be gained by careful examination

and analysis of critical attributes that distinguish these individ-

uals from less successful individuals. Because innate differ-

ences have traditionally been viewed as impossible to modify,

researchers have been interested primarily in innate differ-

ences that can be detected in children at very early ages and

thus aid parents, teachers, and coaches in guiding these chil-

dren into the domain appropriate to their talents. Selecting a

domain is more difficult if, as Galton believed, general talents

predispose a child for eminence in almost any domain. If there

is such a thing as a general talent, availability and the child's

early interest in a domain would govern the selection of a do-

main for early start of practice. Both the hypotheses of general

and domain-specific talents would predict that a child would

exhibit signs of talent after a short period of exposure to the

domain. This raises the possibility that talent revealed early

provides the environmental support and motivation for the

early start of practice and the high levels of deliberate practice

observed while individuals are attaining expert performance.

According to this hypothesis, early talent is the cause of in-

creased practice, and the correlation between practice and elite

performance is confounded by differences in initial talent.

In the following discussion we reexamine the evidence, cited

in the introduction to this article, for the role of innate differ-

ences in the attainment of expert performance. The dichotomy

between characteristics that can be modified and those that

cannot may not be valid when we examine the effects of over

394

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

10,000 h of deliberate practice extended over more than a de-

cade. We first consider the possibility that many of the physical

characteristics of elite performers are the result of adaptation to

many years of intense training and are not a direct expression of

genes. We then discuss the abilities and characteristics dis-

played by children and "idiot savants" and consider whether

these abilities are acquired through normal learning and adap-

tation. We discuss the relation between early performance and

late performance in the acquisition of skill and expert perfor-

mance, and we review evidence on the qualitative differences

that emerge with extensive practice. We review evidence for the

role of early talent and parent-offspring relations in acquired

performance. Finally, we offer an alternative account in terms

of "perceived talent" and predisposition to deliberate practice.

Distinct Physical Characteristics of Elite Performers

Perhaps the most commonly cited evidence for innate talent

is that elite athletes in many types of events have unique physi-

cal advantages. The physical and anatomical differences be-

tween elite athletes and less successful athletes or even normal

adults are often simply assumed to reflect pure genetic factors.

However, some of these differences may not be innate but in-

stead may be the result of physiological adaptations to ex-

tremely intense practice extended over many years. If these

characteristics are purely genetic, it should be possible to dem-

onstrate that they are inherited and that they are manifest in

the absence of any special environmental influences. Ideally, it

should be possible to specify the biochemical mechanisms that

control the emergence of these characteristics.

Height is an excellent example of a characteristic for which

the genetic mechanism has clearly been demonstrated. It is

well-known that genetic factors closely determine height in in-

dustrialized countries with adequate nutritional support (Wil-

son, 1986). In developing countries such as Mexico (Malina &

Bouchard, 1991), the average height of well-nourished individ-

uals can be as much as 7 inches higher than the average height

of undernourished individuals. The age at which the highest

increases in height are observed during development also ap-

pears to be genetically determined (Malina & Bouchard, 1991).

Environmentally induced differences in the height of newborn

monozygotic twins disappear during development (Wilson,

1986). Moreover, the primary method of altering height, except

for reduction by surgery, consists of supplementary injections

of growth hormone during development. All of this persuasive

evidence compels us to attribute adult height primarily to ge-

netic factors when nutritional requirements are met.

One might assume that all or most morphological character-

istics of the bodies of adults are similarly determined primarily

by genetic factors. Studies comparing elite athletes to other ath-

letes and nonathletes have revealed systematic differences in

sizes of hearts, lungs, bones, and muscles; proportions of slow-

twitch and fast-twitch muscles; amount of fat; number of capil-

laries supplying blood to muscles; as well as in aerobic power

and ability. Many of these differences were originally believed

to be almost completely determined by genetic factors in the

normal population of adults. Considerable empirical work has

shown, however, that these differences have only a moderate

genetic component (Bouchard, 1986). In a recent study Fagard,

Bielen, and Amery (1991) found reasonably high genetic com-

ponents for maximal aerobic and anaerobic power even when

differences in the amount of exercise and other life-style factors

were controlled. However when testing was made at submaxi-

mal levels—more comparable to normal activity levels—the

amount of exercise and other life-style factors accounted for all

systematic variance. This result suggests that many physiologi-

cal characteristics are the result of adaptation to a level of daily

activity.

For older sedentary adults, additional scheduled walks im-

prove aerobic ability, whereas young adults require sustained

training at around 75% of maximal heart rate to realize im-

provements (Ericsson, 1990; Haskell, 1989). Extended exercise

programs show that aerobic ability is not fixed but can be dra-

matically changed. After a year of exercise, adults can increase

their aerobic activity up to 35% and in some instances up to

50% (Haskell, 1989). However, to reach the aerobic ability of

elite endurance athletes, average nonathletes would have to in-

crease their aerobic ability by 75%. In Haskell's (1989) view, this

fact supports the role of genetic factors; but Haskell's inference

is based on extrapolation from training programs for fully devel-

oped adults, programs that last a fraction of the duration

known to be required to attain expert-level performance in

sports.

Detailed examinations of the anatomical changes resulting

from intense exercise reveal that the human body is remarkably

adaptable. The number of capillaries supplying blood to mus-

cle fibers changes after a few weeks of practice (Salmons &

Henriksson, 1981). Increased numbers of mitochondria, as well

as other biochemical changes, which increase the efficiency of

metabolic processes, result from extended exercise (C. Wil-

liams, 1990). Even the characteristics of muscle fibers can be

changed, namely from fast-twitch to slow-twitch and vice versa.

Although this conversion of muscle fibers has been docu-

mented in animal research (Salmons & Henriksson, 1981), a

review by Howald (1982) showed that the fiber conversion dem-

onstrated in animals can be generalized to human skeletal mus-

cles. There is good evidence that environmental conditions can

influence the volume of the lungs. Greksa (1988) examined

individuals of the same ethnic and racial background who at

various ages moved from locations at sea-level to a location at

over 10,000 feet. He found that the younger the age at the time

of the move to high altitude, the larger the lung capacity and the

depth of chest.

The best evidence linking intensive training directly to ob-

served changes in heart size comes from longitudinal studies of

young athletes attaining expert performance and of older ath-

letes terminating their careers and practice regimens. Elovianio

and Sundberg (1983) found that elite long-distance runners ac-

quired greater aerobic power and larger heart volumes during a

5-year period of training but showed no initial superiority at age

14. Rost (1987) found during a longitudinal study of children

from age 8 to 11 that heart volumes increased much more in

young swimmers than in nontrained children (control). It ap-

pears that at least 1 year of intense training is required before

the size of a human heart begins to change. Similarly, once

athletes terminate their training the increased heart sizes re-

main, but in the absence of exercise the heart volume regresses

to within normal range over a 10-year period; Rost (1987) re-

THE ROLE OF DELIBERATE PRACTICE

395

ports a volume reduction of 42% in one case. Howald (1982)

reports case studies of top athletes who were forced to stop or

reduce training because of injuries. Drastic decrements in the

percentage of their slow-twitch fibers occurred within 6 months

to 1 year.

Because most sports involve only some of the muscles in the

body, it is possible to contrast these intensively trained muscles

with other muscles in the same athletes. Tesch and Karlsson

(1985) examined the size and frequency of fast- and slow-twitch

fibers in the muscles of different types of elite athletes as well as

of students serving as control subjects. They found that differ-

ences in the percentage of slow-twitch fibers in elite athletes'

muscles occur only for muscles specifically trained for a sport

(legs in runners and back muscles in kayakers), with no differ-

ences for untrained muscles.

Some physiological changes, such as heart enlargements, re-

quire years of increasingly intense practice to emerge and take

years to regress once training is stopped. For example, Eriks-

son, Engstrom, Karlberg, Saltin, and Thoren (1971) found that

swimmers' aerobic ability decreased by 29% five years after

training had stopped. The increased lungs and hearts of these

swimmers had not changed yet. Other changes are gained and

lost more rapidly. For example, aerobic power in bicyclists

(Burke et al., 1990) increases over 50% during the competitive

season every year. Female gymnasts reduce the proportion of

their body fat from average levels by 50% during the competi-

tive season (Reilly & Secher, 1990). Within a week of no train-

ing, swimmers lose on average 50% of the respiratory capacity

of their muscles (Reilly, 1990b), but regaining this capacity

takes considerably longer during retraining.

In sum, most anatomical characteristics, unlike height, are

remarkably adaptable to intense physical activity extended over

long periods of time. Detailed biochemical mechanisms me-

diating the transformation of the phenotype of muscle fibers in

response to intense physical activity (Booth, 1989) and general

mechanisms for influence of environmental factors on develop-

mental outcomes are now being proposed and evaluated (Gott-

lieb, 1992). Many extreme physical characteristics in elite ath-

letes are the result of the same adaptive processes that deter-

mine similar characteristics in the normal population, and the

extreme differences in these attributes correspond to the

equally extreme differences in the amount and intensity of

practice between these two groups.

A reasonable objection to the generalizability of the effects of

training for all adults can be made on the basis of the large

dropout rate for adults from exercise programs (Martin & Dub-

bert, 1985). It is apparently not possible to motivate all people

to engage in regular exercise. Research on the effects of ex-

tended exercise in animals has demonstrated that intensive ex-

ercise results in conversion of muscle fibers (Pette, 1984) and

enlargement of hearts (Harpur, 1980). The primary method for

motivating animals to exercise vigorously is punishment, for

example, running on a treadmill with a slope to avoid a bar

giving electric shock or swimming with or without additional

weights. However, similar but less pronounced effects have

been attained from animals that voluntarily run in a wheel

compared with those in a sedentary condition (Harpur, 1980).

Recent research has shown activity-specific physiological

changes resulting from extended practice also in the central

nervous system. After difficult acrobatic training an increased

number of synapses in the cerebellar cortex were found for rats,

but not for rats engaged in extensive physical exercise, which

instead exhibited a greater density of blood vessels in the same

area (Black, Isaacs, Anderson, Alcantara, & Greenough, 1990).

Replications of the adaptive changes with animals under con-

trolled conditions are likely to be the best obtainable evidence

on generalizability given the problems of motivating random

samples of humans.

Early Demonstrated Abilities Assumed to Reflect Innate

Talent

In the introduction we mentioned several abilities demon-

strated by children and idiot savants that have been thought to

reflect innate talents and predispositions. In this section we

consider one of these abilities, perfect pitch, in detail. We also

briefly discuss other abilities of idiot savants and some of the

anatomical characteristics of ballet dancers and swimmers.

Perfect pitch (or absolute pitch), the ability to identify iso-

lated musical tones, is considered a sign of musical talent. Often

future elite musicians and musical savants exhibit perfect pitch

at an early age. Qualitatively different processes mediate the

performance of individuals with perfect pitch and that of musi-

cians who lack it. Individuals with absolute pitch tend to con-

fuse tones with the same location in different subscales but not

tones having the smallest difference in fundamental frequen-

cies. For example, an untrained subject might confuse C with B,

whereas a subject with perfect pitch would confuse C in one

octave with C in a different octave (Ward & Burns, 1982). Sev-

eral empirical findings suggest that perfect pitch is an acquired

skill. Individuals with "perfect pitch" differ in their ability to

judge pitches and perform best when judging pitches generated

with the instrument they play. As the tests of ability to recog-

nize pitch get harder, as they do when artificially generated

sinus tones are used, for example, fewer and fewer subjects pass

the tests (Oakes, 1955). In addition, adults can acquire perfect

pitch after extended training. P. T. Brady (1970) demonstrated

that he was able to acquire perfect pitch by an intriguing train-

ing procedure, which involved learning to identify a single tone.

Brady reported that once developed, the identification task re-

quired little effort and that he did not have to practice purpose-

fully to maintain the skill. No decrement in performance was

reported after 6 months, and only a slight decrement was re-

ported after 13 years (Costall, 1985). Finally, recent research

(Cohen & Baird, 1990) provides evidence that normal children,

especially before age 5, more easily recognize notes individually

(absolute pitch) before they perceive notes as part of larger mu-

sical structures (relative pitch). These findings suggest that sub-

jects with absolute pitch acquire the necessary skill as children

and then simply maintain it for the rest of their lives (Miyazaki,

1990). Young children's acquisition of absolute pitch is intrigu-

ingly similar to the ease with which they learn a second lan-

guage (J. S. Johnson & Newport, 1989), and with Japanese sub-

jects learning to make the difficult distinction between [r] and

[1] in English (Yamada, 1991).

The importance of early practice and experience for adult

ability is similarly found in swimming and ballet. Ballet train-

ing must start before dancers reach age 11 to gain the necessary

396

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

flexibility of joints. Stress induced during extensive training at

young ages appears necessary for dancers to gain the necessary

"turn out" in the different positions of demi-plie at adult ages

(DiTullio et al., 1989; A. Watkins, Woodhull-McNeal, Clark-

son, & Ebbeling, 1989). Dancers apparently acquire flexibility

through early training as shown by a longitudinal study (Klemp

& Charlton, 1989). In a large group of club swimmers (aged

8-17) the only physical measures discriminating this group

from a matched control group of other types of athletes were

ankle and shoulder flexibility (Poppleton & Salmoni, 1991).

Statistically controlling for age, these two measures of flexibil-

ity were the best predictors of the swimmers' speed; however,

no measure of current or past practice was included in the

analysis. Consistent with the hypothesis that increased flexibil-

ity is acquired through extended swimming, it is common that

elite swimmers have weak ankles, which are particularly suscep-

tible to injury (Chambliss, 1988).

Certain exceptional abilities in idiot savants have been taken

as evidence that innate talent accounts for exceptional perfor-

mance. Given the low general level of these individuals' intellec-

tual functioning, it has seemed plausible that exceptional mem-

ory for some types of material and exceptional perceptual abili-

ties, such as perfect pitch, reflect inherited basic capacities. But

recent research has shown that these exceptional abilities are

more consistent with acquired skill than with innate talents

(Howe, 1990). Often these individuals' performance on tasks

measuring their abilities is exceptional only compared with

their general level of functioning, which is otherwise low (Erics-

son & Faivre, 1988). On the other hand, college students' perfor-

mance on these tasks can be dramatically improved. Training

studies for memory for numbers (Chase & Ericsson, 1982), date

calculation (Addis & O. A. Parsons, unpublished and described

in Ericsson & Faivre, 1988), and mental calculation (Stas-

zewski, 1988) have shown that within weeks, college students

can attain levels of performance outside the range of normal

adult performance. Careful examination of idiot savants and

other individuals with exceptional abilities suggests that they

rely on mechanisms similar to those used by trained students,

and that these individuals have had access to necessary infor-

mation and opportunity to practice prior to the first public

demonstration of their abilities (Ericsson & Faivre, 1988; Howe,

1990).

The only exceptional performance that has not been

matched in a training study is certain individuals' immediate

memory for music they have not heard previously. However,

even in this case, recent studies refute the possibility that this

memory performance reflects some basic, superior memory

capacity (Charness, Clifton, & MacDonald, 1988; Sloboda,

1991). Superior memory is limited to music of familiar struc-

ture and does not transfer to modern atonal music (Sloboda,

Hermelin, & O'Connor, 1985). This finding is consistent with

one from all other instances of exceptional memory (Ericsson,

1985), namely, that knowledge mediates superior performance.

In addition, Judd (1988; see Treffert, 1989, for additional refer-

ences to blind musical savants) has pointed out that most of the

musical savants with superior memory for music were blind.

The only way they could learn new pieces of music was to

memorize them by listening to them. Thus blindness provided

the prerequisite motivation to acquire this memory skill. With

extended practice, their memory performance for music in-

creased and reached exceptional levels.

In summary, exceptional abilities observed in children and

idiot savants are consistent with all the characteristics of ac-

quired skills. Most of them can be easily acquired by adults

through known training methods, although some of them may

be more easily acquired during childhood. The motivational

factors that lead children and idiot savants to focus their time

and energy on activities that improve performance are still

poorly understood.

General Difficulties of Predicting Ultimate Performance

From Initial Performance: Qualitative Differences

Acquired Through Extended Practice

In the introduction we briefly reviewed the difficulties of

predicting the level of expert performance individuals attain

after extended practice. Bound up with the notion of innate

talents, which are revealed during early performance, is the

notion that the same fixed components determine both early

performance and the final level of performance and thus enable

observers to identify and select future exceptional performers as

well as to predict their final achievement after practice. In this

section we briefly review the literature on individual differ-

ences in performance as a function of practice in studies of skill

acquisition. We then review some findings on the nature of

individual differences in expert performance.

Extensive research on skill acquisition with college students

and more representative samples, such as military recruits,

shows that performance on a wide range of tasks improves

monotonically as a function of many hours of practice. Current

theories (J. R. Anderson, 1982; Fitts, 1964; Fitts & Posner, 1967)

propose that initial performance is mediated by sequential pro-

cesses, which with additional practice are transformed into a

single direct (automatic) retrieval of the correct response from

memory. This radical change in processing makes it difficult to

identify any locus for individual differences in innate talent

that could influence initial superiority as well as superior final

performance. The most successful attempts to relate individual

differences in ability to individual differences in performance

have dealt with short-term skill acquisition. Evidence from

these studies suggests that performance during the initial, mid-

dle, and final phase of skill acquisition is correlated with differ-

ent types of abilities in each phase (Ackerman, 1988), initial

performance being correlated with general cognitive abilities

and final performance with perceptual-motor abilities. This

evidence is consistent with the current theories of skill acquisi-

tion. With several hours of practice, cognitive differences are

essentially eliminated, giving way to the more "basic" differ-

ences in components associated with perception and motor pro-

duction. Because, however, the perceptual and motor systems

show great adaptability in response to extended practice (a phe-

nomenon discussed earlier in this article), it may be inappropri-

ate to generalize the findings from relatively simple tasks in-

volving 2-20 h of practice to expert performance acquired dur-

ing a 10-year period of intense preparation.

Two general findings concerning individual differences in

high levels of performance imply that expert performance and

initial performance do not have a common basis. First, most

THE ROLE OF DELIBERATE PRACTICE

397

individual differences related to levels of elite performance are

due to the amount and organization of knowledge, which every-

one agrees must have been acquired. Finally, memory perfor-

mance for briefly presented stimuli relevant to a given domain

differs as a function of the level of performance in those do-

mains (Chase & Simon, 1973; for a review see Ericsson and

Smith, 199 lb), but does not generalize to scrambled versions of

the same stimuli. Hence experts' superior memory perfor-

mance must be mediated by knowledge about the domain,

knowledge that enables them to encode meaningful relations

between the elements of the stimuli.

The second general finding is that expert performers have

acquired skills that enable them to circumvent general memory

and processing limits. Chase and Simon (1973) originally attrib-

uted experts' superior memory to chunking in short-term mem-

ory. This account has been revised, and the exceptional mem-

ory of experts has been shown to reflect rapid storage in long-

term memory (Charness, 1976; Frey & Adesman, 1976; Lane &

Robertson, 1979). Building on Chase and Ericsson's (1982)

skilled memory theory, Ericsson and Staszewski (1989) con-

cluded that experts acquire memory skill enabling them to rap-

idly access relevant information in an extended working mem-

ory that relies on storage in long-term memory. This acquired

memory skill underlies experts' superior ability to plan and

evaluate potential sequences of moves in chess (Charness, 1981,

1989), sequences of card exchanges in bridge (Charness, 1989),

and alternative diagnoses in medicine (Patel & Groen, 1991).

The most important implication of these acquired memory

skills is that they enable experts to circumvent the limited stor-

age capacity of short-term memory. Thus these skills eliminate

any restrictive influence of individual differences in this basic

capacity (Ericsson & Smith, 1991b).

In tasks involving motor performance, experts can similarly

circumvent basic limits of sequential processes (Salthouse,

1991). It is plausible that after extended practice, the ultimate

reaction time on a simple task depends on the speed of the

neural and motor components of the response process in a

simple reaction. However, individual differences in simple reac-

tion time are essentially unrelated to expert performance

(Starkes & Deakin, 1984). Furthermore, the speed of motor

processes is faster than would be expected from a sequence of

simple reactions. Expert typists can type at great speed because

they prepare several typing responses in advance of the next

typing response, a finding which Gentner (1988) documented

by high-speed filming of experts' finger movements on the key-

board. Monitoring of expert typists' eye fixations reveals that

they look ahead in the text to be typed, and the extent to which

they do so is strongly correlated with their typing speed

(Butsch, 1932). Experimental manipulations of the number of

characters that are displayed in advance (preview) show that a

certain preview is necessary for maximal typing speed. Reduc-

tion of preview below that amount decreases typing speed, and

without preview, expert typists type at speeds comparable to

those of novices (Salthouse, 1984). Experts' typing speed be-

comes constrained by several new factors, such as the need to

use the same finger in consecutive key strokes and indepen-

dence of movements between and within hands. Similarly,

when expert pianists prepare a musical piece for public perfor-

mance, they spend considerable time determining how to hit

keys with different fingers and thereby minimize such con-

straints on movement.

The ability to anticipate future events and thus prepare ac-

tions in advance is critical in many domains of expertise, partic-

ularly in sports. Abernathy and Russel (1987) showed tennis

players pictures of an opponent in different phases of preparing

to serve. They found that with increasing levels of expertise,

tennis players can use advance cues, such as location of arms

and racquet, to predict where the tennis ball will hit in the

service area. Shown pictures of an attacking field-hockey

player preparing a shot, national-level field-hockey players can

predict where the ball will go even before the attacking player's

club has made contact with the ball (Starkes, 1987). The impor-

tant implication of this research is that experts can circumvent

any basic limits on the serial motor processes constraining a

novice by using advance cues to prepare movements.

In summary, research on skill acquisition indicates that per-

formance in the initial phases of practice is determined by char-

acteristics quite different from those that determine perfor-

mance during later phases. Considering that expert perfor-

mance is acquired during a decade of intense preparation, the

evidence suggests that relevant practice activities during devel-

opment lead to far greater changes in basic perceptual and mo-

tor abilities than previously thought. What distinguishes expert

performers is mostly more and better organized knowledge,

which had to have been acquired. Most important, recent re-

search on expertise shows that experts can acquire cognitive

skills enabling them to circumvent the limits of short-term

memory capacity and serial reaction time. This research rules

out the hypothesis that individual differences in those func-

tions will influence and constrain final adult performance and

is consistent with the low predictability of performance by abil-

ity tests after extended relevant experience (Hulin et al., 1990).

Finally, because the criteria for expert performance in most

domains change as a function of age and level of performance,

it appears unlikely that the study of early performance will

reveal fixed elements that determine the level of final adult

performance.

The Role of Perceived Talent, Motivation, and

Predisposition for Practice

From our search for immutable characteristics correspond-

ing to innate talent, we conclude that individuals acquire vir-

tually all of the distinguishing characteristics of expert per-

formers through relevant activities (deliberate practice). At least

one characteristic, height, cannot be acquired. However, even

height is imperfectly related to expert performance, and adult

height has a correlation of only around 0.8 with height at ages

younger than 17 to 18 (Malina & Bouchard, 1991), when deci-

sions to start practice are made. Apparently no valid informa-

tion on innate talent is available during an individual's initial

exposure to the domain. In spite of this, assessments of talent

and decisions to initiate deliberate practice are as a rule made

during this period (Bloom, 1985b). The perception that a child

is talented is unquestionably real, and such perceptions moti-

vate parents to provide the time and money to support deliber-

ate practice as well as to encourage their children in a particular

domain. In the normal case (Bloom, 1985b), the child enjoys

398

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

the activities in the domain and is superior in these activities to

other children of the same age in the same neighborhood.

Whether enjoyment precedes superior performance or vice

versa is not known. In either case, perceived talent and enjoy-

ment of the activities of a domain are ideal preconditions for

initiating the effortful but valuable activity of deliberate prac-

tice. Our framework differs from a view that is based on innate

talent in that we emphasize the motivation and enjoyment nec-

essary to start and maintain deliberate practice and the motiva-

tion of parents and coaches to support the individuals without

assuming that the initial superior performance reflects immuta-

ble characteristics (innate talent).

In this section we show that our framework not only explains

the facts but also gives a better account of them than a frame-

work that is based on innate talent. First, we examine detailed

descriptions of observed talent (Scheinfeld, 1939), and we then

argue that expert performers' familial relations can be ac-

counted for by shared environment. The central argument is

first that the perception that an individual is talented, that is,

innately equipped and predestined for success in a domain,

leads to the early start of deliberate practice. Second, the indi-

vidual attains an elite level of adult performance by maintain-

ing a high level of practice. Note that the perception of innate

talents will be relatively immune to disconfirming evidence so

long as the talents are kept general and unspecified. As a result

such a perception can continue to bolster an individual

throughout his or her development.

The classic studies of innate talent emphasized that talent is

observed very early before the start of deliberate practice.

Scheinfeld (1939) found that the age at which talent is first

noticed is quite young for truly outstanding musicians—an

average of 4.9 years of age. Scheinfeld's descriptions suggest

that "talent" means promise rather than objective evidence of

unusual capacity. For example, "unusual response to music" at

age 3 (p. 238) and "playing violin with two sticks" at age 4 (p.

239) would not be impressive in children at older ages. Exam-

ples of talent for the oldest ages (6-7 years) in Scheinfeld's re-

view nearly always involve absolute pitch. These accounts are

consistent with Bloom's (1985b) interviews with parents and

teachers of international-level performers; Bloom found that

the level of talent exhibited by these individuals was only un-

usual compared with that of other children of a similar age in

the immediate environment. We find this evidence more con-

sistent with demonstrated interest and enjoyment of a domain

than with any superior, innate advantage involving fixed capaci-

ties.

To identify these early expressions of interest it is critical that

adults closely observe their children and are willing to support

this interest and provide access to deliberate practice. The im-

portance of the early environment is clearly evident in our find-

ing that children who become elite performers are first exposed

to a domain and start practice at remarkably young ages. At

these young ages it is more plausible that parents' perception of

innate talent, not objective evidence, leads to the start of prac-

tice. In fact, evidence of talent does not precede most instances

of very early start of practice. Many parents of precocious chil-

dren were convinced of the great importance of very early sys-

tematic training and attribute the remarkable abilities of their

children to the training and not to inherent talent. Howe (1990)

reviewed the education of John Stuart Mill, Norbert Wiener,

and William Sidis. An outstanding feature of these early educa-

tional efforts was the total elimination of inherently enjoyable

activities such as play and social interaction with other children.

This feature is consistent with our assertion that deliberate

practice is not inherently enjoyable. More recently, a Hungarian

educator, Polgar, announced a similar educational experiment

with his daughters involving early and focused training in chess

(J. Radford, 1990). All three daughters developed into highly

skilled chess players (ranked first, second, and sixth in the

world among women chess players in 1992) and the youngest

daughter, Judith, recently became the youngest grand master

ever in chess (McFadden, 1992). Given the biological relation

between parent and children, these cases clearly do not rule out

hereditary influences, but they do show that the level of perfor-

mance can be dramatically accelerated through systematic

training initiated prior to evidence of talent.

Better evidence for our framework would go beyond showing

improvement from practice without knowledge of talent and

show that individuals with negative talent, for example, a dis-

ability, have attained great performance through practice. No

theory of expert performance would give individuals with dis-

abilities an advantage or even opportunity compared with nor-

mal individuals. Individuals with disabilities have nevertheless

attained international-level performance and even won Olym-

pic medals. The gold medal winner at Melbourne in hammer

throwing was born with a paralyzed left arm and devised new

training techniques to overcome the disadvantage of his disabil-

ity (Jokl, 1958). The first female to win three Olympic gold

medals in the same games, Wilma Rudolph, lost the use of her

left leg at the age of 4 and after intense treatment and practice

was able to walk without braces and reinforced shoes by age 11

(Ladd, 1988). In these cases subnormal performance seems to

have motivated the individuals' start to deliberate practice as a

means of reaching normal functioning and then to continue

practice to reach elite levels. Several athletes have experienced

severe injuries, but were able to overcome these disabilities and

win Olympic medals for their performance (Jokl, 1964). One

suffered amputation of the arm used to hold the pistol in shoot-

ing. Another, a rider, contracted polio and lost control of her

legs. These examples indicate that training can compensate for

disabilities and has a greater impact than often believed

possible.

The fact that children who later attain expert performance

share their early environment with their parents would seem a

satisfactory explanation of familial relations to expert perfor-

mance. The most often cited examples of families of gifted

musicians are from early music, Johann Sebastian Bach's family

tree being the most striking (Rowley, 1988; Scheinfeld, 1939). In

those times before the advent of professional music teachers,

the transmission of knowledge and skills from parent to child

was natural and did not presuppose any genetic transmission of

innate talent. Similarly, nobody would argue that bilingual chil-

dren who speak a foreign language have innate abilities for

speaking that particular language. Obviously they have ac-

quired that language through social interaction with their par-

ents or grandparents. Similarly, it is likely that in many cases

parents transmit to their children a substantial amount of

knowledge and motivation in skilled activities in a domain. In a

THE ROLE OF DELIBERATE PRACTICE

399

recent study in behavioral genetics, Coon and Carey (1989)

compared the music performance of identical and fraternal

twins and found that the environmental correlations were al-

ways higher than the genetic ones. (Whether the same findings

would emerge if the study were restricted to expert musical

performance is unknown; given the low frequency of expert

musicians, an appropriate study of twins would be nearly im-

possible to conduct.) Similarly, de Garay, Levine, and Carter

(1974) interviewed more than 1,200 athletes attending the 1968

Olympic games in Mexico City and found no meaningful famil-

ial resemblance in reported physical or motor abilities between

these athletes and their families compared with a reference

group.

In summary, our review has uncovered essentially no support

for fixed innate characteristics that would correspond to gen-

eral or specific natural ability and, in fact, has uncovered find-

ings inconsistent with such models. At the same time we recog-

nize that parents and teachers who perceive talent in their chil-

dren and pupils are motivated to provide them with instruction

and social support. We also recognize that being told by parents

and teachers that they are talented, that is, genetically endowed

with unusual gifts, most likely increases motivation, boosts

self-confidence, and protects young performers against doubts

about eventual success during the ups and downs of the ex-

tended preparation. A famous violin teacher, Galamian (1962),

discusses the importance of giving praise to build self-confi-

dence, but warns against too much praise as it causes "them to

relax their efforts (p. 106)." Too much recognition at young ages

may lead young musicians to consider themselves as special

individuals—not just musicians—deserving of treatment as

prima donnas in all aspects of everyday life (Gelber, 1990).

Research in social psychology on interpersonal expectation

and self-fulfilling prophesies confirms these effects in the labo-

ratory and in everyday settings (Darley & Fazio, 1980; Ro-

senthal & Rubin, 1978). The important influence of parents'

expectations on their children's performance, interest, and self-

judgments of ability in a domain has been demonstrated for

large random samples in the general population. Children's and

adolescents' perception of their own ability in mathematics is

influenced by their parents' beliefs about their abilities, even

when past performance and effort are statistically controlled

for (Parsons, Adler, & Kaczala, 1982). The parents' beliefs in

gender differences in talent in mathematics and English influ-

ence their perception of their children's abilities more than is

warranted given the objective differences in performance be-

tween boys and girls for these two subjects (Eccles, Jacobs &

Harold, 1990). Recent studies have uncovered pathways by

which the parents' beliefs influence children's beliefs in their

own abilities as well as their performance. Harold, Eccles,

Yoon, Aberbach, and Freedman-Doan (1991) have shown how

the child's gender influences the parents' perception of the

child's ability in sports and music, which in turn influences the

frequency of opportunities for relevant activities provided by

parents for their children in the corresponding domain. Eccles

and Harold (1991) have linked the influence of gender on the

child's self-concept in English, mathematics, and sports and the

influence of self-concept on how much free time is spent on

activities in the corresponding domain. Hence, parental beliefs

and expectations tan influence the children's relevant experi-

ences directly by offering opportunities or indirectly by

strengthening motivation and self-confidence for a given activ-

ity. In addition, laboratory studies, where amount of experience

is equated, show that implicit theories of stability of abilities are

an important aspect of individuals' self-concept and greatly in-

fluence future learning goals and reactions to failure (Dweck &

Leggett,1988).

Returning to Galton's framework, we reject any important

role for innate ability. It is quite plausible, however, that herit-

able individual differences might influence processes related to

motivation and the original enjoyment of the activities in the

domain and, even more important, affect the inevitable differ-

ences in the capacity to engage in hard work (deliberate prac-

tice). In this review we have already pointed out the motiva-

tional problems associated with persuading adults to start and

maintain exercise programs and with getting children to start

and maintain deliberate practice. Individual differences in

emotionality and general level of activity are also likely influ-

ences on the capacity to engage in sustained practice as well as

on the preference or dislike for this type of isolated activity.

Moderate heritabilities have been estimated for these differ-

ences (Plomin et al., 1990) and for self-reported interest in espe-

cially artistic activities (Grotevant, Scarr, & Weinberg, 1977).

Although we are not aware of any controlled human studies

relating activity levels and emotionality to deliberate practice

and attained level of expert performance, the relation between

productivity and eminence (Simonton, 1984) is at least consis-

tent with such a relation. In addition, Cox (1926) estimated IQ

from early achievements documented in biographies of the

hundred most eminent men of recent centuries but concluded

that "high but not the highest intelligence, combined with the

greatest degree of persistence, will achieve greater eminence

than the highest degree of intelligence with somewhat less per-

sistence" (p. 187). The pattern of results from animal studies is

remarkably consistent with the importance of such relations

and interesting from an evolutionary perspective. Early behav-

ioral geneticists were able to selectively breed strains of rats that

performed differently on specific learning tasks (McClearn,

1962). Contrary to expectation, the superior learning ability of

these rats was specific to the parameters of the task, such as

types of relevant cues (visual vs. spatial) and types of motivation

(hunger vs. escape from water). Furthermore, "bright" and

"dull" rats differed in either emotionality or activity or both

(McClearn, 1962). In a classic study, Scott and Fuller (1965)

examined the characteristics and test performance of several

breeds of dogs and found that the only general factor was emo-

tion. Rather than viewing the emotional and activity factors as

variables confounding pure learning factors, K. J. Hayes (1962)

proposed viewing them as integral and necessary prerequisites

for learning and acquired skill in animals as well as humans.

Future research will tell whether individual differences in fac-

tors related to individuals' motivation to practice can account

for any heritable influences in attained levels of performance.

Conclusion

People believe that because expert performance is qualita-

tively different from normal performance the expert performer

must be endowed with characteristics qualitatively different

400

K. ERICSSON, R. KRAMPE, AND C. TESCH-ROMER

from those of normal adults. This view has discouraged scien-

tists from systematically examining expert performers and ac-

counting for their performance in terms of the laws and princi-

ples of general psychology. We agree that expert performance is

qualitatively different from normal performance and even that

expert performers have characteristics and abilities that are

qualitatively different from or at least outside the range of those

of normal adults. However, we deny that these differences are

immutable, that is, due to innate talent. Only a few exceptions,

most notably height, are genetically prescribed. Instead, we

argue that the differences between expert performers and nor-

mal adults reflect a life-long period of deliberate effort to im-

prove performance in a specific domain.

Most of our scientific knowledge about improvement and

change comes from laboratory studies of training and practice

that lasted hours, days, and occasionally weeks and months. In

addition, there is a growing body of data on the heritabilities of

various abilities and characteristics estimated for twins and

parents and their offspring sampled from the general popula-

tion (Plomin et al., 1990). Although behavioral geneticists care-

fully point out that their heritability estimates are valid only for

the limited range of practice and skill in the normal environ-

ment of the adults studied, it is often incorrectly assumed by lay

people that these estimates can be directly extended to extreme

manipulations of environmental conditions, such as extended

deliberate practice. Most important, the effects of short-term

training cannot be readily extended to the effects of orders of

magnitude more practice.

A promising direction for research on the effects of extended

activities is to identify activities relevant to some goal and to

assess the amount of time individuals allocate to these activi-

ties. Recent research has shown that the amount of time individ-

uals spend reading as assessed by diaries is related to memory

for prose even when education and vocabulary are partialed out

(Rice, Meyer, & Miller, 1988). The estimated amount of read-

ing is also related to reading ability and, most interestingly,

increases in reading ability (R. C. Anderson, Wilson, & Field-

ing, 1988). Research on physical fitness has a long tradition of

measuring daily physical activity and exercise, and we have

cited the study in which Fagard et al. (1991) assessed the influ-

ence of both genetic factors and regular activity on aerobic and

anaerobic abilities. It would be ideal to plot the interaction of

genetic and environmental factors in longitudinal studies

across the entire life span (Rutter, 1989). Within this context,

we view the study of elite performers as particularly interesting

because from early ages their lives appear to maximize the

influence of environmental activities (deliberate practice) im-

proving a specific type of performance. In a rare study

Schneider, Bos, and Rieder (1993) included environmental fac-

tors along with physical characteristics and motivational char-

acteristics of individuals in a longitudinal study of elite tennis

players. Consistent with our framework they found that tennis

performance at ages 11 and 17 was primarily determined by

parental support and in particular motivation and tennis-speci-

fic skills, where the level of these skills in turn are mainly attrib-

utable to assessed levels of motivation and concentration.

We view elite performance as the product of a decade or more

of maximal efforts to improve performance in a domain

through an optimal distribution of deliberate practice. This

view provides us with unique insights into the potential for and

limits to modifying the human body and mind. Many anatomi-

cal characteristics, traditionally believed to be fixed, can adapt

and change in response to intense practice sustained for years.

Substantial change and learning can occur even during child-

hood, when some changes, such as in certain perceptual-motor

abilities, might be even easier to attain than during adulthood.

Untrained adults can overcome limits on speed and processing

capacity by acquiring new cognitive skills that circumvent these

limits by qualitatively different processes. Further research on

the capacities and characteristics of expert performance will

give us a much deeper understanding of the full range of possi-

ble adaptations and methods for circumventing limits (Ericsson

& Smith, 1991a).

It does not follow from the rejection of innate limits on ac-

quired performance that everyone can easily attain high levels

of skill. Contemporary elite performers have overcome a num-

ber of constraints. They have obtained early access to instruc-

tors, maintained high levels of deliberate practice throughout

development, received continued parental and environmental

support, and avoided disease and injury. When one considers in

addition the prerequisite motivation necessary to engage in de-

liberate practice every day for years and decades, when most

children and adolescents of similar ages engage in play and

leisure, the real constraints on the acquisition of expert perfor-

mance become apparent. The commitment to deliberate prac-

tice distinguishes the expert performer from the vast majority

of children and adults who seem to have remarkable difficulty

meeting the much lower demands on practice in schools, adult

education, and in physical exercise programs.

We believe that a more careful analysis of the lives of future

elite performers will tell us how motivation is promoted and

sustained. It is also entirely plausible that such a detailed analy-

sis will reveal environmental conditions as well as heritable

individual differences that predispose individuals to engage in

deliberate practice during extended periods and facilitate moti-

vating them. Our empirical studies have already shown that

experts carefully schedule deliberate practice and limit its dura-

tion to avoid exhaustion and burnout. By viewing expert per-

formers not simply as domain-specific experts but as experts in

maintaining high levels of practice and improving perfor-

mance, we are likely to uncover valuable information about the

optimal conditions for learning and education.

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Received April 14, 1992

Revision received December 11,1992

Accepted December 11,1992 ■

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