| Research with both infants and adults suggests that the processes underlying the perception of animate and inanimate (or living and non-living) things may differ. Indeed, several researchers have suggested that the perception of faces and of human movement may be mediated by specialized mechanisms. Two phenomena set adults' ordinary perceptions of faces and of human movement apart from their perceptions of animate objects: First, inversion of the stimulus display impedes recognition. Second, these complex forms appear to be perceived as a global unity. These two phenomena interact with one another: global processing appears to occur only when the figure is displayed in its canonical orientation. The studies presented here examine the development of these phenomena in the perception of human form from motion-carried information. In particular, these studies sought to determine whether and when infants perceive point-light displays of human form as a unitary whole.; In order to probe infants' sensitivity to the unity of human form, we presented two displays: a unitary-axis display, in which limbs oscillated around a single axis, and a divided-axis display, in which the principal axis was split at the midriff and the halves offset horizontally. In Experiment 1, 12-, 20-, and 28-week-old infants were tested for the discrimination of these displays in an infant-control habituation paradigm. At 28 weeks, infants discriminated the displays when the displays were presented upright, but not inverted. At 20 weeks, infants showed a trend toward this pattern. However, 12-week-old infants failed to discriminate the displays in either orientation.; Three subsequent studies were conducted to explore 12-week-old infants' non-discriminatory response. Though analysis of previous and current findings suggest that young infants are sensitive to intra-limb spatio-temporal configuration, the results of the studies presented here are inconclusive. Taken together, the results of these studies suggest that, between 12 and 20 weeks, infants become sensitive to the global unity of human form. Concomitantly, responses become orientation-specific, Implications of this pattern of responses, and its resemblance to those documented in face recognition, are examined. |
