Crowding is similar for eye movements and manual responses

Crowding is an ambiguity in the peripheral vision that occurs when a target is surrounded by other –similar- objects. Crowding is typically studied using manual responses. Peripheral vision, however, is used for planning eye-movements. This begs the question whether crowding as measured when participants respond with their eyes is different from when they respond by hand, while fixating. On top of that, recent reports suggest either reduced or increased crowding around saccade initiation. If such effects would significantly influence crowding this would be important to know. In this experiment, a reference and a target (an oriented target Gabor) were positioned either left or right of a central fixation point. To measure the perceived position of the target, observers indicated the position of the target (the right most tilted one). Conditions involved presenting isolated reference and target, as well as conditions in which both were surrounded by identical flankers. Target selection was indicated by the participant either via button responses or via eye movements. Results revealed that responding by eye or by hand did not affect target recognition performance. Response times were also similar. Hence, we conclude that for all practical purposes, crowding can be considered identical for either type of response. Meeting abstract presented at VSS 2014