When two eyes are better than one in prehension

Previous research suggests that binocular vision plays an important role in prehension. A number of studies have demonstrated changes in the kinematics of prehension when binocular vision is removed. Complementary studies have begun to explore what binocular information is used and how this information is exploited by the human nervous system. The present series of experiments was conducted in order to explore further when binocular information is advantageous in prehension. Three experiments were employed which varied binocular/monocular viewing in selectively lit conditions. Our research suggests that the nature of the advantage conferred by binocular vision depends upon task conditions. One constant advantage of binocular vision appears to be in its provision of on-line information regarding the position of the hand relative to the target. In reduced cue conditions (ie where a view of the target is lost after initiation of the movement), binocular vision appears to be particularly useful in the initial programming of reach distance. These results are a step towards establishing when the removal of binocular vision affects prehension.