Categorization studies of 9- to 15-month-old infants: Evidence for superordinate categorization?

Abstract

Four experiments examined the ability of infants 9 to 15 months of age to form a category superordinate to a related basic-level category. Procedures, stimulus conditions, and dependent measures were the same as in previous studies reporting basic-level categorization ( bird) in 9-month-olds. In Experiments 1 through 3, infants were habituated to three different kinds of animals but did not categorize even by 15 months of age. The basic-to-superodinate order of emergence reported for young children and its explanation in terms of category differentiation might be extended into infancy. In Experiment 4, 15-month-olds habituated to six different animals provided evidence suggesting successful categorization. Increasing the number of exposure exemplars appears to facilitate categorization. Maternal interviews revealed that 15-month-olds appear to comprehend basic-level terms for some of the animal stimuli used. This suggests an assimilation of conceptually independent basic-level categories into a higher order superordinate grouping (Nelson, 1985). Finally, a reliable linear increase in recovery to test stimuli of decreasing prototypicality suggests that graded internal structure may characterize the superordinate category formed.