Categorization and Abstract Similarity in Chess

Chess experts remember meaningful chess positions better than novices (de Groot, 1978; Chase & Simon, 1973). This can be explained with a larger number of chunks in experts’ long-term memory (Gobet & Simon, 1998). These chunks are mainly based on visual representations—that is, pieces on squares. However, a recent experiment highlighted that experts prefer to group chess positions by abstract similarities that cannot be explained purely visually (Linhares & Brum, 2007). Based on these data it was claimed that chess expertise, in addition to chunks, crucially relies on abstraction and analogies. These data and the conclusions were heavily criticized because the instructions strongly biased the participants to group positions in a certain way (Bilalić & Gobet, 2009). Here, we successfully replicated this experiment with less explicit instructions. In addition, we collected category labels for the groupings that allowed us to explore the abstract principles that participants used.