Shifted visual feedback of the hand affects perceived reachability of moving objects

Abstract

In many situations in which one reaches out to interact with an object one must estimate when the object will be reachable. Thus motion of the object relative to the body has to be taken into account. When one does not interact directly with the object in question, and the object does not move relative to ones body, judgments of reachability are influenced by displaced visual feedback about the position of ones hand. Here we examine whether displaced feedback of the hand also influences reachability judgments when the task is to interact with a moving object. Subjects saw virtual cubes that moved along straight paths in various directions. Their task was to intercept the virtual cube with their unseen index finger as soon as the cube was judged to be reachable. If the cube could not be reached along the entire path, subjects were instructed to keep their index finger at the starting position. Subjects received visual feedback about the position of their index finger, but this feedback was shifted in depth by 5 cm, either away from or closer to their body. The feedback disappeared when the arm was extended or when the hand came close to the virtual cube. Perceived reachability increased when feedback of the hand was shifted away from the body and decreased when the feedback was shifted closer to the body. We conclude that visual feedback about the position of the hand affects the perceived reachability of moving objects.

Footnotes

 Supported by European Science Foundation, Eurocores CNCC CRP grant, and Grant SEJ2006-27544-E from the Spanish Government.