Got a spare 10,000 hours laying around you ain't usin'?
Well get usin' it and become and expert at something for the first
time in your miseable existence.
No wonder I ain't a rock star, I only spent 8,000 hours playin the dam
Expert Performance and Deliberate Practice
An updated excerpt from Ericsson (2000)
EXPERTISE refers to the mechanisms underlying the superior achievement
of an expert, i.e. "one who has acquired special skill in or knowledge
of a particular subjects through professional training and practical
experience" (Webster's dictionary, 1976, p. 800). The term expert is
used to describe highly experienced professionals such as medical
doctors, accountants, teachers and scientists, but has been expanded
to include any individual who attained their superior performance by
instruction and extended practice: highly skilled performers in the
arts, such as music, painting and writing, sports, such as swimming,
running and golf and games, such as bridge and chess.
When experts exhibit their superior performance in public their
behavior looks so effortless and natural that we are tempted to
attribute it to special talents. Although a certain amount of
knowledge and training seems necessary, the role of acquired skill for
the highest levels of achievement has traditionally been minimized.
However, when scientists began measuring the experts' supposedly
superior powers of speed, memory and intelligence with psychometric
tests, no general superiority was found --the demonstrated superiority
was domain specific. For example, the superiority of the chess
experts' memory was constrained to regular chess positions and did not
generalize to other types of materials (Djakow, Petrowski & Rudik,
1927). Not even IQ could distinguish the best among chessplayers
(Doll & Mayr, 1987) nor the most successful and creative among artists
and scientists (Taylor, 1975). In a recent review, Ericsson and
Lehmann (1996) found that (1) measures of general basic capacities do
not predict success in a domain, (2) the superior performance of
experts is often very domain specific and transfer outside their
narrow area of expertise is surprisingly limited and (3) systematic
differences between experts and less proficient individuals nearly
always reflect attributes acquired by the experts during their lengthy
In a pioneering empirical study of the thought processes mediating the
highest levels of performance, de Groot (1946/1978) instructed expert
and world-class chessplayers to think aloud while they selected their
next move for an unfamiliar chess position. The world-class players
did not differ in the speed of their thoughts or the size of their
basic memory capacity, and their ability to recognize promising
potential moves was based on their extensive experience and knowledge
of patterns in chess. In their influential theory of expertise, Chase
and Simon (1973; Simon & Chase, 1973) proposed that experts with
extended experience acquire a larger number of more complex patterns
and use these new patterns to store knowledge about which actions
should be taken in similar situations.
According to this influential theory, expert performance is viewed as
an extreme case of skill acquisition (Proctor & Dutta, 1995; Richman,
Gobet, Staszewski & Simon, 1996; VanLehn, 1996) and as the final
result of the gradual improvement of performance during extended
experience in a domain. Furthermore, the postulated central role of
acquired knowledge has encouraged efforts to extract experts'
knowledge so that computer scientists can build expert systems that
would allow a computer to act as an expert (Hoffman, 1992).
Among investigators of expertise, it has generally been assumed that
the performance of experts improved as a direct function of increases
in their knowledge through training and extended experience. However,
recent studies show that there are, at least, some domains where
"experts" perform no better then less trained individuals (cf.
outcomes of therapy by clinical psychologists, Dawes, 1994) and that
sometimes experts' decisions are no more accurate than beginners'
decisions and simple decision aids (Camerer & Johnson, 1991; Bolger &
Wright, 1992). Most individuals who start as active professionals or
as beginners in a domain change their behavior and increase their
performance for a limited time until they reach an acceptable level.
Beyond this point, however, further improvements appear to be
unpredictable and the number of years of work and leisure experience
in a domain is a poor predictor of attained performance (Ericsson &
Lehmann, 1996). Hence, continued improvements (changes) in achievement
are not automatic consequences of more experience and in those domains
where performance consistently increases aspiring experts seek out
particular kinds of experience, that is deliberate practice (Ericsson,
Krampe & Tesch-Römer, 1993)--activities designed, typically by a
teacher, for the sole purpose of effectively improving specific
aspects of an individual's performance. For example, the critical
difference between expert musicians differing in the level of attained
solo performance concerned the amounts of time they had spent in
solitary practice during their music development, which totaled around
10,000 hours by age 20 for the best experts, around 5,000 hours for
the least accomplished expert musicians and only 2,000 hours for
serious amateur pianists. More generally, the accumulated amount of
deliberate practice is closely related to the attained level of
performance of many types of experts, such as musicians (Ericsson et
al., 1993; Sloboda, et al., 1996), chessplayers (Charness, Krampe &
Mayr, 1996) and athletes (Starkes et al., 1996).
The recent advances in our understanding of the complex
representations, knowledge and skills that mediate the superior
performance of experts derive primarily from studies where experts are
instructed to think aloud while completing representative tasks in
their domains, such as chess, music, physics, sports and medicine
(Chi, Glaser & Farr, 1988; Ericsson & Smith, 1991; Starkes & Allard,
1993). For appropriate challenging problems experts don't just
automatically extract patterns and retrieve their response directly
from memory. Instead they select the relevant information and encode
it in special representations in working memory that allow planning,
evaluation and reasoning about alternative courses of action (Ericsson
& Lehmann, 1996). Hence, the difference between experts and less
skilled subjects is not merely a matter of the amount and complexity
of the accumulated knowledge; it also reflects qualitative differences
in the organization of knowledge and its representation (Chi, Glaser &
Rees, 1982). Experts' knowledge is encoded around key domain-related
concepts and solution procedures that allow rapid and reliable
retrieval whenever stored information is relevant. Less skilled
subjects' knowledge, in contrast, is encoded using everyday concepts
that make the retrieval of even their limited relevant knowledge
difficult and unreliable. Furthermore, experts have acquired domain-
specific memory skills that allow them to rely on long-term memory
(Long-Term Working Memory, Ericsson & Kintsch, 1995) to dramatically
expand the amount of information that can be kept accessible during
planning and during reasoning about alternative courses of action.
The superior quality of the experts' mental representations allow them
to adapt rapidly to changing circumstances and anticipate future
events in advance. The same acquired representations appear to be
essential for experts' ability to monitor and evaluate their own
performance (Ericsson, 1996; Glaser, 1996) so they can keep improving
their own performance by designing their own training and assimilating
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