de Groot, Adrian
Adrian de Groot (1914-2006) was a Dutch psychologist and chess master who did the first psychological enquiry into the minds of chess players. His 1965 book, Thought and Choice in Chess, showed the different abilities of masters and amateurs. He found that masters can recall 93% of all the pieces on a board of a chess position from a game (not random) after looking at it for 4 seconds. Experts remembered 72% and weaker chess players were able to recall only 51% of the pieces. When random positions were shown, all levels of players recalled the same percentage of pieces. This suggested that masters were able to use some form of chunking, or pattern-matching, that allowed them to recall the positions. He played on the Dutch Olympiad team in 1936, 1937, and 1939.