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Ryohei Nakayama, Isamu Motoyoshi, Tsutomu Kusano, Takao Sato; Spatial motion coordinates that determine perceptual dominance in binocular rivalry. Journal of Vision 2012;12(9):1264. doi: 10.1167/12.9.1264.
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© ARVO (1962-2015); The Authors (2016-present)
It is known that moving stimuli dominate in binocular rivalry over static stimuli. Recent evidence shows that visual motions can be processed in spatiotopic or object-based as well as retinotopic coordinates. Here we examined relative contribution of these coordinates by independently manipulating motions of grating stimulus, background, and fixation marker. Six observers dichoptically viewed a pair of diagonal gratings with different orientations (45 and 135 deg). The grating for one eye was static while that for the other eye was drifting (6 deg/sec). There was a gray background (6.3 x 9.4 deg) surrounding each stimulus together with a fixation marker presented on the left side of grating stimulus. The observers judged which grating appeared dominant during 2 sec trials. The contrast ratio where dominance balances was obtained by systematically varying contrasts. Eye movements were monitored. It was found that drifting gratings were dominant over static gratings when observers maintained stationary fixation. However, when they tracked the fixation marker that moved together with the drifting grating, the physically drifting but retinotopically static gratings became dominant, indicating that retinal motion by itself is not the determining factor. When the background was moved together with the fixation marker, the gratings drifting in retinotopic and object-based coordinates dominated over physically drifting gratings. Thus, the existence of object-based motion seems the determining factor, but it is not since gratings with both retinotopic and physical motion but with no object-based motion became dominant when background alone was moved. These results, therefore, indicate that retinal motion is not the determinant for the dominance. Subsequent quantitative analyses revealed that the contribution of spatiotopic and object-based motions to the dominance are equal or even larger than retinotopic motion. These results demonstrate a significant involvement of non-retinotopic motion signals in triggering the conscious awareness of visual stimuli.
Meeting abstract presented at VSS 2012
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