Chess Playing Helps Reveal How Brain Works
"Imagine yourself as a chess player about to checkmate your opponent," Grafman said in describing the work of the brain. "All your knowledge and experience are being retrieved for your next move. First, you perceive the pieces on the board and mentally separate the color-coded pieces. Then you analyze their positions on the board, identify the value of the different pieces, and retrieve the rules of the game for any move. If you are a skilled player like the 10 subjects in this study, you also recognize specific patterns that signify when you have an advantage over your opponent. Finally you have to analyze the consequences of your potential moves and the countermoves of your opponent."
A brain imaging technique called positron emission tomography (PET) allowed Grafman and his coworkers to separate these steps and identify the parts of the brain used during each stage. A PET brain scan records the increased use of a radioactive tracer when a part of the brain is activated for a particular task.
For chess players, color separation and spatial discrimination activate parts on both sides of the brain toward the back of the head known to be associated with visual processing. Rule retrieval activates two parts on the left side of the brain, a small structure deep within the brain associated with indexing memories and a structure in an area near the left ear associated with memory storage. Checkmate judgment activates areas on both sides near the front of the brain crucial for planning and in the back of the brain important for generating images.
Grafman said experiments like the chess problem are helping improve our understanding of how humans make judgments. According to Grafman, the areas in the front of the brain activated in the checkmate judgment stage may be "managerial knowledge units." These units are similar to other types of storage in the brain but coordinate a large amount of information in a specific sequence. Grafman said the findings in this study will ultimately be useful in helping people recovering from brain injuries or diseases that affect problem solving and judgment.
The NINDS is the nation's principal supporter of research on the brain and nervous system and a lead agency for the Congressionally mandated Decade of the Brain. The Institute supports and conducts a broad program of basic and clinical neurological investigations. The NINDS is part of the National Institutes of Health, located in Bethesda, MD.
*Nichelli, P., Grafman, J., Pietrini, P., Alway, D., Carton, J. C., Miletich, R. 1994. Brain activity during chess playing. Nature, vol. 369, no. 6477, p. 191.