Assimilation of Exceptions? Examining Representations of Regular and Exceptional Category Members Across Development

Evidence from multiple category learning studies suggest that exceptions to a category rule are remembered better than the items that follow that rule (Davis, Love, & Preston, 2012; Palmeri & Nosofsky, 1995; Sakamoto & Love, 2004). Based on differences in recognition memory, it has been suggested that category exceptions may be represented separately from regular category members. Here, we present 4 experiments investigating representations of regular and exceptional category members as well as potential developmental changes in these representations. Although 4-year-olds and adults demonstrated different memory patterns, both age groups showed (a) higher memory sensitivity for regular members of the category and (b) isomorphic memory patterns for regular and exception items. Additionally, we report important developmental differences in generalization patterns. In children, features of regulars and of exceptions contributed to categorization of both regular and exception items. In contrast, an asymmetry was found in adults: features of regulars contributed to categorization of both regular and exception items, whereas features of exceptions contribution only to categorization of exceptions. These findings challenge the hypothesis that items that violate known knowledge structures have a special status in memory and suggest that exceptions can be represented jointly with regular items early in development and as a subset of regular items later in development.