Infant Saccadic Eye Movements to Visible and Previously Visible Targets

Abstract

Recent evidence has shown that 1- and 2-month-old infants localize a peripheral target by means of a series of saccades. Step size in a series was directly related to target distance, but within a localizing series did not vary appreciably as the line of sight approached the target. The current study examined whether, during localization of a peripheral target, step size and number of steps were determined prior to the first saccade in a localizing series. 2-month-olds viewed peripheral targets which either remained on (continuous condition) or were extinguished (interrupted condition) prior to target localization. It was found that on the majority of trials a series of saccades was made toward the target hemifield. In both conditions the size of each saccade in a multiple saccadic series was approximately equal within a given trial, but varied with initial target distance. Multiple saccades on both continuous and interrupted trials were similar in form, differing only in the total extent of eye rotation. This suggests that a similar oculomotor program was operating under both conditions.