Use of the image-retina and eye-head movement visual systems during coincidence-anticipation performance

Movement is visually detected by one of two systems: (a) the image-retina system (image moves along stationary retina), or (b) the eye-head movement system (eye moves to keep image stationary on retina). Previous research has shown that subjects, when they have to respond to movement to execute a coincidence-anticipation task, will choose the image-retina system or the eye-head system, but it has failed to establish the superiority of either system. The present study was designed to examine this issue. Young adults (n = 28) of both sexes performed two series of 12 coincidence-anticipation trials each. Three stimulus speeds were administered in a randomized order, standardized across subjects. Eye movements were recorded with the head stabilized. In one series, subjects were instructed to follow the stimulus with their eyes. In the other, they were told to fix on the target point and watch the stimulus in their peripheral vision. Half of the subjects initiated testing in each condition. Time error was converted to percentage of viewing time. A three-way analysis of variance (condition x stimulus speed x sex) showed that percentage error was significantly smaller in the image-retina condition than in the eye-head movement condition, and that error increased significantly with increasing speed. Males were better than females. Therefore, the image-retina system may be superior with tasks where the stimuli move at speeds necessitating saccadic eye movements.