Deference in Categorisation: Evidence for Essentialism?

Many studies appear to show that categorization conforms to psychological essentialism (e.g., Gelman & Wellman, 1991). However, key implications of essentialism have not been scrutinized. These are that people’s categorizations should shift as their knowledge of micro-structural properties shift, and that people should defer in their categorizations to appropriate experts. Three studies are reported. The first shows that even gross changes in genetic structure do not radically shift categorizations of living kinds. The second and third reveal a pattern of conditional deference to experts, coupled with systematic deference to non-experts. It is argued that these results point towards only a partial role for essentialism in explaining categorization, and a continuing role for theories that emphasize the importance of appearance and/or functional properties.