Variable coordination of eye and head movements during the early development of attention: a longitudinal study of infants aged 12-36 months.

This longitudinal study investigated the effects of attentional development on peripheral stimulus localization by analyzing the eye and head movements of toddlers as they matured from 12 to 36 months. On each trial of an experiment, a central fixation point and a 30° peripheral stimulus were presented, such that in the gap condition the fixation disappeared 300 ms before the peripheral stimulus, whereas in the no-overlap condition it disappeared simultaneously as the peripheral stimulus, and in the overlap condition the fixation remained present when the peripheral target occurred. Results showed that eye and head movement latencies were highly correlated in all conditions and ages. However, at 12 months, head movements were as fast as eye movements, whereas during the subsequent development, eye movements became increasingly faster than head movements. These findings are indicative of a transition between 12 and 36 months due either to a change in attentional control, or to changes in the size of the visual field in which only eye movements occur.