Abstract
After the adaptation to the moving stimulus that is composed of high and low spatial frequency sinusoidal gratings moving in the opposite directions, observers perceive motion aftereffect (MAE) in the direction opposite to the high and low spatial frequency components with static and flicker tests, respectively. (Shioiri & Matsumiya, VSS 06). We showed that smooth pursuit eye movements (SPEM) after the adaptation followed the similar pattern of MAE percept at a static test (Matsumiya & Shioiri, VSS 06). The present study investigated direction of MAE percept and SPEM after the adaptation to a plaid stimulus with static and dynamic tests. An adaptor was composed of two gratings with different spatial frequencies moving in the orthogonal directions of plus or minus 45 deg. The test stimulus was the same as the adaptor except for motion. The test was either static or 4Hz-flickered. The adaptor was presented for 20 s and followed by test gratings. Test stimulus was presented for 2 s and observers adjusted the direction of a probe to indicate the direction of MAE. We varied the contrast of the high spatial frequency grating with fixed contrast of the low spatial frequency grating to examine the effect of relative strength of MAE between the two components. High spatial frequency superiority of MAE was found for both perception and SPEM with the static test. The direction of SPEM as well as the MAE direction was closer to the opposite of the motion of the high spatial frequency grating than that of the low spatial frequency grating. Similarly, perception and SPEM showed low spatial frequency superiority of MAE with the flicker test. We also found that the effect of contrast was similar for perception and SPEM with both tests. These results suggest that pursuit and perception share a motion processing system.
This study was supported by Grant-in-Aid for Scientific Research #18330153 and #18047005 to S.S. and #18700253 to K.M.