FORMING CONTEXTUAL CATEGORIES IN INFANCY

The role of context in categorization was examined in four experiments with 3-month-olds. In all experiments infants learned to kick their feet to activate a mobile on 3 successive days. Infants were trained with a different mobile exemplar during each daily session. Categorization of a physically dissimilar novel object (Butterfly) was assessed 1 to 14 days later. In Experiments 1A and 1B, infants were trained and tested in a highly distinctive context. They included Butterfly in the mobile category after 1 and 7, but not after 14, days (Experiment 1A). This latter result was due to a categorization failure because infants did respond to another novel exemplar of the original training series after 14 days (Experiment 1B). In Experiment 2A, infants who were passively exposed to Butterfly for 3 minutes in the distinctive context at the end of category training responded to Butterfly 1 day later when it was encountered ''out of context.'' This result was also obtained in Experiment 2B when the distinctive context was present only during the final training session. Taken together, these findings demonstrate that categorization of a novel object is influenced by the context present when the object is initially encountered and by previous encounters with that object in the category context. Clearly, infants are capable of contextual categorization very early in the first year of life.