Abstract
How a static object’s position and orientation relative to oneself change when one moves one’s head can be used to judge the object’s distance. There are three distance cues that change when moving one’s head: the direction of gaze that is required to fixate the object, the orientation of the object with respect to such a direction of gaze, and the object’s position relative to distant objects in the retinal image. They do so to an extent that depends on the object’s distance and on the magnitude of the head movement. When making goal-directed arm movements we inevitably move our head to some extent. To find out which, if any, of the above-mentioned cues influence distance judgments under such circumstances, we conducted a study in which participants had to move their index finger to virtual objects in the dark. The objects’ sizes and positions varied across trials, with pairs of trials in which the same object was presented at the same location, except that one or more of the three above-mentioned cues was artificially manipulated to indicate that the object was either nearer or further away. We found that all three cues influence the movement endpoints, but the magnitude of the influence shows that the cues only contribute a few percent to the judged distance.
Meeting abstract presented at VSS 2015