Does the Size-Illusion Effect on Prehensile Movements Depend on Preview Duration for Visuomotor Process?

ABSTRACT

Given that visual estimation of an object's size is affected by an illusory figure, the present study investigates the Ebbinghaus size-illusion effect on visuomotor performance within different preview durations for viewing an object (no preview, 300, 700, 1500, and 3000 ms) before initiating the movement. Twenty participants performed the following actions: (a) grasping the object and (b) matching the perceived object size with the finger aperture configuration as in the grasping task. The illusion affected the grasping aperture size only in the no- and 300-ms preview durations, while the matching aperture was affected across all preview conditions. These results suggest that the preview duration influences the size illusion to affect the grasping performance, and subjects adopt different visuomotor processes, depending on preview duration.

Keywords:

• Ebbinghaus illusion
• prehension
• visuomotor
• visuomotor processing