Sensitivity to rotational motion in early infancy.

Sensitivity to rotational motion, one of the fundamental components of optic flow, was tested in infants aged 2 and 3 months. The infants in both groups showed significant sensitivity to rotational motion only in the high-speed condition (10.62 degrees/s). There was no significant increase in motion sensitivity between 2 and 3 months of age, indicating that there is not a significant developmental change during this period. A comparison of our results with previous findings that showed a significant increase in radial motion sensitivity between 2 and 3 months suggests that different motion sensitivities have different developmental time courses.