Infants flexibly use different dimensions to categorize objects.

A sequential-touching task was used to investigate whether 14-month-old infants can rapidly change how they categorize a set of objects, recognizing new groupings of objects they had previously categorized in a different way. When presented with a collection of objects that could be categorized by shape (balls vs. blocks) or material (soft vs. hard), infants who showed stable performance on a superordinate-level categorization task or who had larger receptive vocabularies exhibited flexible categorization; they categorized the objects by material as well as by shape. Infants who rarely responded to the superordinate-level categorization task or who had smaller receptive vocabularies, in contrast, categorized primarily by shape. Thus, flexible categorization is related to development in other cognitive domains.