Both a looking time habituation and a modified forced-choice preferential looking (FPL) technique indicate that infants younger than six months of age discriminate optic flow patterns that simulate only large (>20°) changes in the direction of observer-motion along a simulated ground plane. Two experiments were conducted to examine whether infants' sensitivity differs under display conditions where information about heading direction and motion in depth is enriched. In Experiment 1, 3-, 4-, and 5-month-old infants were tested using FPL to measure discrimination between optic flow displays that simulated translation at 5 m/s along different trajectories of motion (12-90°) through a cloud-like pattern of random dots that filled two 15° (H) by 30° (V) regions at the 90 cm viewing distance. In Experiment 2, 3- to 6-month-olds were tested using similar techniques but with visually rich displays generated using a 3D animation rendering system. The displays incorporated visual cues to depth and direction change such as optic expansion, texture gradients, horizon cues, accretion and deletion of contours, and motion parallax. The data from both studies confirm the previous findings that heading direction discrimination thresholds are large (20-70°) in young infants and decline only modestly with increasing age. Enriched visual displays do not result in substantially lower discrimination thresholds relative to previous reports of responses toward ground plane patterns. Consequently, the relatively poor discrimination abilities found previously appear not to be due to specific display-related factors, but instead may reflect a diminished sensitivity to changes in the direction of self-motion that are specified by visual information.
All Science Journal Classification (ASJC) codes
- Sensory Systems