How Experts Solve Problems • 347to 1,000 patterns for a good player and few or none for a poor or beginning player
(Bedard & Chi, 1992). But what is important for the purposes of problem solving is
not just that the expert’s mind contains lots of knowledge, but that this knowledge is
organized so it can be accessed when needed to work on a problem.Experts’ Knowledge Is Organized Diff erently From Novices’ The difference in orga-
nization between experts and novices is illustrated by an experiment by Michelene Chi
and coworkers (1982; also see Chi et al., 1981). They presented 24 physics problems
to a group of experts (physics professors) and a group of novices (students with one
semester of physics) and asked them to sort the problems into groups based on their
similarities. ● Figure 12.19 shows diagrams of problems that were grouped together
by an expert and by a novice. We don’t need a statement of the actual problems to see
from the diagrams that the novice sorted the problems based on surface characteristics
such as how similar the objects in the problem were. Thus, two problems that included
inclined planes were grouped together, even though the physical principles involved in
the problems were quite different.
The expert, in contrast, sorted problems based on structural features, such as gen-
eral principles of physics. The expert perceived two problems as similar because they
both involved the principle of conservation of energy, even though the diagrams indi-
cate that one problem involved a spring and another an inclined plane. Thus, novices
categorized problems based on their surface features (what the objects looked like) and
the experts categorized them based on their deep structure (the underlying principles
involved). Experts’ ability to organize knowledge has been found to be important not
only for chess masters and physics professors, but for experts in many other fi elds as
well (Egan & Schwartz, 1979; Reitman, 1976).Experts Spend More Time Analyzing Problems Experts often get off to what appears
to be a slow start on a problem, because they spend time trying to understand the prob-
lem rather than immediately trying to solve it (Lesgold, 1988). Although this may slow
them down at the beginning, this strategy usually pays off in a more effective approach
to the problem.2 lb
Vo = 4 ft/s2Length Length.15 mK = 200 nt/mProblem 21Problem 24Problem 23Problem 24.6 mNovice
The novice grouped problems 23 and 24
together because they both involve
similar objects (inclined planes).Expert
The expert grouped problems 21 and 24
together because they both involve similar
physics principles (conservation of energy).μ= .2μ μ●FIGURE 12.19 The kinds of physics problems that were grouped together by novices
(left) and experts (right). (Source: Based on M. T. H. Chi, P. J. Feltovich, & R. Glaser, “Categorization and
Representation of Physics Problems by Experts and Novices,” Cognitive Science, 5, 121–152, 1981. Reprinted by
permission of Taylor & Francis Group.)Copyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.