The emergence of perceptual category representations in young infants: a connectionist analysis

There has been recent interest in the idea that principles governing learning in connectionist networks can form the basis for an alternative understanding of developmental processes (Elman, Bates, Karmiloff-Smith, Johnson, Parisi, & Plunkett, 1996). The present paper can be viewed as a case example of the usefulness (and limitations) of connectionist modeling for the study of infant cognition. Specifically, the paper reports on a series of connectionist models designed to analyze the factors responsible for the emergence of global-level and basic-level category representations in young infants. The models (1) simulated the formation of global-level and basic-level representations, (2) revealed a global-to-basic order of category emergence, (3) uncovered the formation of two distinct global-level representations-an initial "self-organizing" perceptual global level and a subsequently "trained" arbitrary (i.e., nonperceptual) global level, and (4) displayed a gradual transition from perceptual global-level to perceptual basic-level representation with increasing exposure to training stimuli. Hypotheses for empirical investigations of category development in infants that follow from the modeling efforts are discussed.