CONCEPT-FORMATION IN INFANCY

Four experiments investigated conceptual categorization in 7- to 11-month-old infants. Experiments 1 and 2 showed that 9- and 11-month-olds differentiated the global domains of animals and vehicles. Within the animal domain no subcategorization was found: the infants did not differentiate dogs from fish or from rabbits. Within the vehicle domain infants differentiated cars from both airplanes and motorcycles. Experiment 3 showed similar, although weaker, categorization for 7-month-olds. Experiment 4 showed that categorization of animals and vehicles was unaffected by degree of between-category similarity. Birds and airplanes were treated as different even though the exemplars from both categories had similar shapes, including outstretched wings, and were of the same texture. These data, showing global differentiation of animals and vehicles, with lack of differentiation of ''basic-level'' categories within the animal domain, contrast with data from studies designed to assess perceptual categorization. Even younger infants differentiate various animal subcategories perceptually. However, the results presented here suggest that infants may not respond to such perceptual differences as being conceptually relevant.