A kinematic analysis of goal-directed prehension movements executed under binocular, monocular, and memory-guided viewing conditions

Vision is critical for the efficient execution of prehension movements, providing information about: The location of a target object with respect to the viewer; its spatial relationship to other objects; as well as intrinsic properties of the object such as its size and orientation. This paper reports three experiments which examined the role played by binocular vision in the execution of prehension movements. Specifically, transport and grasp kinematics were examined for prehension movements executed under binocular, monocular, and no vision (memory-guided and open-loop) viewing conditions. The results demonstrated an overall advantage for reaches executed under binocular vision; movement duration and the length of the deceleration phase were longer, and movement velocity reduced, when movements were executed with monocular vision. Furthermore, the results indicated that binocular vision is particularly important during ''selective'' reaching, that is reaching for target objects which are accompanied by flanker objects. These results are related to recent neuro psychological investigations suggesting that stereopsis may be critical for the visual control of prehension.