Expertise and Domain Specific Knowledge

An expert is a person who has learned to solve problems or answer questions relating to a particular "problem solving domain" or area of expertise. Much problem solving involves domain-specific knowledge. That is knowledge relevant to a certain domain that is an environment or situation or class of problems. Domain-specific knowledge is what makes an expert an expert.

What distinguishes an expert? How does this relate to domain-specific knowledge?

Each environment requires its own sort of expertise. Living "on the street" as a homeless person in a major city requires a whole repertoire of behaviors and knowledge and assumptions that most of us lack. The same could be said of running a high-energy physics lab, or running a successful car dealership, or playing a musical instrument. Virtually any area of human accomplishment requires knowledge unique to that domain. Domain-specific knowledge allows the expert to do things that baffle or frustrate a beginner. The expert makes it look easy, but the expert achieves this behavior only after long hours of practice.

How is expertise accumulated?


A meaningful configuration (top) and a random configuration (bottom)

Experts may invest tens of thousands of hours in developing domain-specific knowledge. Chase and Simon (1973) estimated that chess experts spend up to 50,000 hours learning to play chess. That works out to 4 hours of chess a day for over thirty years. Simon and Gilmartin (1973) estimated that, as a result of this experience, the chess expert can recognize between 10,000 and 100,000 distinct patterns of chess pieces on a chessboard.

What did DeGroot discover?

A huge "vocabulary" of chess configurations (knowledge of tactically important positions on a chess board) enables the expert to grasp the layout of a chessboard almost immediately. Some chess masters can play 20 chess games simultaneously, moving from board to board, winning almost all the games. In a classic study, DeGroot showed that chess masters had a fantastic memory for chess positions. Masters were able to reconstruct an entire chessboard full of positions after only about 5 seconds of inspection.

What did Chase and Simon show, in research following up on DeGroot's study?

Chase and Simon (1973) did follow-up research in which they tested experts and beginning players with randomly placed pieces. With random positions (those which did not make sense in chess) experts were no better at memorizing board positions than beginners. With meaningful positions, the experts were much better than beginners. The difference is shown in the figure. An actual mid-game configuration is on the top, a random configuration is below. To the expert there is a big difference! Only the configuration on the top is easy for the expert chess player to memorize, because it relates to the expert's accumulated schemas. To the non-player, neither picture relates well to past experience, so either can be memorized equally easily.

The same is true in any domain of expertise. The expert learns to recognize significant patterns and remember them easily. A person who lives in the arctic circle develops a specialized vocabulary for describing different types of ice and snow and probably can memorize the type of snow easily. An expert auto mechanic develops a huge repertoire of patterns to look for when examining an engine, and so forth.

An expert not only learns thousands of patterns and rules; the expert also knows when to break the rules. The expert knows about odd cases that come up "once in a blue moon" or which might not be what they appear to be. The ability to recognize situations where normal rules should not be applied is almost as important as knowing the rules themselves.

In addition to learning thousands of patterns and rules, the expert must learn... what?

Because expertise results from long-term accumulation of experience, there is no quick and easy road to expertise of any kind. Children do not automatically understand this. They may become frustrated when they find out they cannot become skilled at something right away. They must be encouraged to persist in accumulating relevant experience so that someday they might be experts who make it look easy.


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Copyright © 2007 Russ Dewey