Abstract
Control of motor behavior crucially depends on the ability to predict motion of visual objects in space and time. In sports, athletes are usually advised to keep their eyes on the visual object of interest, i.e. the ball, in order to hit or catch it optimally. The resulting smooth pursuit eye movements enable better vision by stabilizing the target on the fovea. At the same time, they produce a retinal velocity error of target and background motion which has to be compensated. Here we report results from experiments that address the question whether smoothly tracking a visual object effectively helps to predict its motion trajectory in space. Human observers tracked or fixated a small visual target with the eyes. In the pursuit condition, the target moved linearly and at a constant velocity towards a stationary vertical line (goal); in the fixation condition, the goal moved towards the stationary target. Presentation duration (200, 600 ms), distance between target and goal (3, 6, 9°), and angular movement direction (90° ± 15°) were varied from trial to trial. Observers had to judge whether the target would hit or miss the goal. Both stimuli were extinguished before the event. Shorter distance of target to goal generally improved prediction performance. Motion prediction during pursuit was not improved by longer presentation duration of target and goal. During fixation, however, performance decreased to chance level for short presentation duration. These results suggest that pursuit eye movements can be advantageous for predicting the trajectory of a moving object in space when motion sampling time is short.
This work was supported by the German Research Foundation (DFG FOR 560).