Cluttered environments: Differential effects of obstacle position on grasp and gaze locations.

Previous research has investigated the effects of nontarget objects (NTOs) on reach trajectories, but their effects on eye-hand coordination remain to be determined. The current investigation utilized an eye-hand coordination paradigm, where a reaching and grasping task was performed in the presence of an NTO positioned exclusively in the right or left workspace of each right-handed participant. NTOs varied in their closeness to the subject and reach-path, between the starting location of the hand and the target-object of the reach. A control condition, where only the target was present, was also included. When an NTO was presented on the right (ipsilateral to the reaching hand), it pushed the final grasp and gaze locations on the target, shifting them to the left-away from the "obstacle." The impact of the ipsilateral NTO was increased as it was moved into positions closer to the participant that were of greater obstruction to the hand and arm. In contrast, when the NTO was contralateral, the risk of collision was low and participants developed a set reach plan that was repeated nearly identically for each contralateral NTO position. Our findings also indicate that the "invasiveness" of the NTO positions had a greater effect on grasp than it did on gaze position-demonstrating how the arrangement of clutter in an environment can differentially affect gaze and grasp when reaching for an object. (PsycINFO Database Record