The effect of occlusion on motion integration in infants

Previous psychophysical studies have shown that the adult human visual system makes use of form information such as occlusion to determine whether to integrate or segregate local motion signals (J. McDermott, Y. Weiss, & E. H. Adelson, 2001). Using the displays developed by McDermott et al., these experiments examined whether occlusion and amodal completion affect motion integration in infants. After familiarizing infants with the displays, infants were tested for preference between coherent motion and local motion displays. The results indicate that 5- to 8-month-olds, but not 3-month-olds, showed a significantly greater preference for the local motion display under occlusion conditions. These results suggest that 5- to 8-month-olds perceive motion to be coherent under occlusion conditions. The results are compatible with previous data showing that amodal completion of static information emerges at around 5-6 months of age (Y. Otsuka et al., 2006a), adding that infants use amodal completion for motion integration at this same time.