512 Procedural Memory and Skill Acquisition
context of a mail-coding task showed no trade-off between
predictive power of cognitive versus perceptual speed tasks,
is that executive control of performance remains important in
most complex tasks.
Skilled performance is generally described as being rela-
tively fast and error-free, but in at least some situations, more
skilled performers are actually more error-prone than less
skilled performers. Bell, Gardner, and Woltz (1997) found
individual differences in the rate of making undetected errors
on a number reduction task, in which numbers were com-
pared according to a series of rules. After a practice session in
which speed was emphasized, participants received a transfer
session emphasizing accuracy and the instruction to press a
key whenever a performance error was detected. Bell et al.
found that the people who were more skilled (as indicated by
faster reaction times during the training session) also made
more undetected errors in the transfer session. The number of
undetected errors was correlated with measures of memory
span, with a larger memory span being associated with a
lower error rate. Speed of processing was also correlated with
the making of undetected errors: Faster processors made
fewer undetected errors. Although speed-accuracy trade-off
can not be ruled out as an explanation for the finding that
latency was negatively correlated with the number of unde-
tected errors made, Bell et al. argue that fluency in a task
brings with it an increased chance of making undetected
errors. Furthermore, detecting errors seems to require work-
ing memory resources, as indicated by the finding that people
with a greater memory span were better able to detect errors.
EXPERTISE
Expertise in a particular domain can be viewed as the end
product of skill acquisition. Unfortunately, it is an end that
most of us do not reach in domains where we are nonetheless
active. What enables some people to become expert in their
field, whether it be playing tennis, solving physics problems,
or playing the viola, and what characteristics distinguish
experts and nonexperts?
One of the most debated topics in this field is whether ex-
pertise is primarily a result of learning or whether some peo-
ple are genetically predisposed to become experts. Although
it seems obvious that heredity can place constraints on the
ability to become an expert, the major factor in developing
expertise seems to be a commitment to years of dedicated
practice. Newell and Simon (1972) were among the first to
suggest that expertise can be explained in terms of the devel-
opment of knowledge and information-processing abilities
(e.g., memory span). Ericsson and Charness (1994) argued
that extended training significantly alters both cognitive and
physiological processes to an even greater degree than sug-
gested by the work of Newell and Simon. They contend that
differences between experts and novices primarily reflect
changes brought about by practice rather than differences in
aptitude or initial ability. It has even been argued that human
expertise can be viewed as the result of circumventing nor-
mal limitations on human information processing (e.g., de-
velopment of parallel processing in typing; Salthouse, 1991).
It may be that prodigious achievements in performance
are rare because talent for a specific activity and the neces-
sary environmental support for the development of that
talent rarely coincide (Feldman, 1986). Gardner (1983), in
particular, has argued that individual differences in aptitude
and ability play a much greater role than that assumed by
Ericsson and his colleagues. Gardner argues that the deliber-
ate practice account of expertise ignores self-selection and
the basis for the ability to engage in the training required to
become an expert. However, there are many cases of excep-
tional performers who did not show any unusual talent early
in childhood but, through sustained, intensive practice,
nonetheless achieved high performance levels (Ericsson &
Charness, 1994).
Chase and Simon (1973; Simon & Chase, 1973) developed
both a skill-based account of expertise and methods for study-
ing expertise. Using expertise in chess as an example, they
attempted to document the expert’s knowledge structures and
processes. Their influential work emphasized the roles of per-
ception and memory in expert performance. According to
Chase and Simon, the development of expertise in chess
relies heavily on chunking. As a result of practice and experi-
ence with the game, experts come to recognize configurations
of chess pieces as groups or chunks rather than as individual
pieces. As chunks develop, increasingly larger configurations
are recognized until the game configuration itself can be
apprehended as one whole. Other researchers (e.g., Charness,
1991) have emphasized the importance of study, in this case,
the study of games of chess masters and strategy, in the
development of expertise in chess. Chess masters themselves
have a great deal of knowledge acquired through study of
books and magazines.
Search and evaluation processes have been shown to have
a separate, and important, role in chess expertise (e.g.,
Charness, 1981), as have heuristic rules and knowledge of
themes, openings, and so forth (Holding, 1985). As suggested
by the work of Chase and Simon (1973), however, whatis
searched appears to be more important than how extensively
or deeply the search is conducted. Chess masters seem to rely
more on pattern recognition than search (although very fast
search times have not been ruled out). Pattern recognition