Visual motion processing in one-month-old infants: preferential looking experiments.

Abstract

The ability of infants to discriminate between opposite directions of motion was assessed using forced-choice preferential looking between a random-dot pattern which was segregated into regions which moved in opposite directions, and a uniform pattern in which all the dots moved in the same direction. The first experiment measured velocity thresholds (Vmin and Vmax) for direction discrimination; between 10 and 13 weeks Vmin decreased, while at the same time Vmax increased. The second experiment explored possible implications of this expanding velocity range for direction discrimination by younger infants. One-month-olds showed no evidence for direction discrimination at any of a number of test velocities in the range 1-43 deg/sec. The 1-month-olds were also tested with two additional conditions: they could discriminate between moving and static patterns at velocities of 10 deg/sec or above, and they could also discriminate between coherent and incoherent motion at velocities of 21 deg/sec or below. Neither of these discriminations depends on sensitivity to the direction of the coherent motion. The results suggest that 1-month-olds may not be sensitive to the direction of visual motion.