Connectivity perception of partly occluded gratings in 4-month-old infants

Four groups of eight 4-month-old infants were each habituated to one of fou r displays consisting of a grating of either low (0.4 cycle deg(-1)) or hig h (1.2 cycles deg(-1)) spatial frequency, whose central portion was covered up with a horizontal occluder which was either narrow (1.33 deg) or broad (4.17 deg). Posthabituation displays consisted of a complete grating of the same frequency as the habituated grating, along with a separate grating wh ose central portion was replaced with a black gap of the same height as the occluder in the habituation displays. All the infants, except those who we re habituated to the high frequency with the broad occluder, looked longer at the separate grating than the complete grating display during posthabitu ation trials. Previously, we found that infants under I month of age percei ve the grating continuation only when the occluder height is less than abou t 0.5 cycle of the grating; our present results show that this figure incre ases to about 1.6 cycles of the grating frequency in the case of 4-month-ol d infants. These findings indicate that those developmental changes depend on both the sufficiency of visual information available and the efficiency of the perceptual ability of infants for grasping spatial relationships.