Availability of Peripheral Optic Flow Influences Whether Infants Cross a Visual Cliff

This report describes a novel test of the prediction that locomotion-induced changes in an infant’s functional utilization of peripheral lamellar optic flow (PLOF) for postural stability contributes to avoidance of the deep side of a visual cliff. To test the prediction, a corridor, with either low-textured or high-textured walls, was constructed to run the length of a visual cliff. The infants, 9.5-month-olds with varying amounts of hands-and-knees crawling experience, were randomly assigned to the low-texture (n = 30) or the high-texture condition (n = 32). Consistent with predictions, the findings revealed significant interactions between crawling experience and texture condition for the probability of crossing and the latency to venture onto the deep side of the cliff. Most notably, more experienced crawlers, but not less experienced crawlers, were significantly more likely to cross the visual cliff to the parents and ventured onto the cliff faster in the high-texture condition than in the low-texture condition. The availability of PLOF thus had an effect on infants’ crossing behavior on the visual cliff. We interpret these findings as evidence for a three-step process in which locomotor-induced changes in visual proprioception play a central role in the development of wariness of heights.