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Ryohei Nakayama, Isamu Motoyoshi, Takao Sato; Competing motion signals compromise to discrete perception. Journal of Vision 2014;14(10):264. doi: 10.1167/14.10.264.
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© ARVO (1962-2015); The Authors (2016-present)
In natural scenes, motion of an object as a whole is usually consistent with motion of local patterns contained within the object. We investigated human visual motion perception in cases where these motions conflict with each other, by using a Gabor pattern whose Gaussian spatial window and carrier grating moved inconsistently with different directions and/or speeds. We found that when spatial window moved constantly whereas the carrier grating stayed still or drifted in the opposite direction, the whole stimulus appeared to move only intermittently. This intermittent jumping motion was most strongly observed when carrier temporal frequency (relative to the window) was 4-8 Hz, and spatial frequency was 0.5-1 c/deg. The similar data was obtained even when the observer tracked the moving spatial window, indicating that the illusion is fundamentally determined at the spatiotopic coordinate. The apparent temporal rate of the jumping increased proportionally with the temporal frequency of the grating for a range from 4 to 10 Hz. Thus, the illusion is not determined by a fixed internal clock. The illusion diminished when the spatial window was surrounded by a sharp luminance edge. This jumping motion probably comes from resetting the positional representation of Gaussian window that occurs only intermittently. The visual system tolerates the discrepancy between the positional information of carrier grating determined clearly by luminance and that of Gaussian window determined only vaguely by a second-order motion (contrast defined) edge, and when the accumulated discrepancy becomes beyond certain limit, the positional representation of window is reset.
Meeting abstract presented at VSS 2014
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