Marjan Persuh¹, Alyssa Costigan; ¹Department of Social and Behavioral Sciences, Manhattan University

One prominent proposal suggests a separation between the vision for action and vision for perception. Actions, however, depend on knowing and representing veridical object properties. The idea that veridical (as opposed to perceptual) information guides motor activity has been independently developed for the phenomenon of response priming. It has been proposed that motor responses in priming are based on the rapid feedforward stream of information processing, which extracts only basic, physical properties of the prime stimulus. We tested this hypothesis using a Furrow illusion, in which a veridical, vertical dot movement in the periphery is perceived as tilted when presented against a tilted background grating. In the first experiment, we asked participants to make speeded responses to the target consisting of a dot moving across a tilted path. Preceding the target, prime was presented in the periphery, which consisted of a dot moving vertically, but due to the Furrow illusion was perceived as moving across a tilted path. We asked whether participants’ responses to targets would be affected by the consciously perceived movement along the tilted path or stay unaffected by the veridical, vertical motion of the primes. Contrary to theoretical expectations, we observed significant effects of primes on rection times to targets, demonstrating that motor responses were affected by the perceived and not veridical direction of motion. In the second experiment we first estimated the size of the illusion for each participant individually and then used that estimate to eliminate the illusion. With this manipulation, veridical motion was slanted, whereas perceived motion was vertical. Surprisingly, reaction times in this experiment were not affected by the veridical motion. In summary, our two experiments demonstrate that our visuo-motor responses use consciously perceived information about objects to guide motor responses.