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Masamitsu Harasawa, Kazushi Maruya, Takao Sato; Perception of motion with orientation-defined missing fundamental gratings. Journal of Vision 2002;2(7):640. doi: 10.1167/2.7.640.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: It has been known that for luminance-defined missing fundamental (MF) with 1/4 cycle shifts is perceived in the direction opposite to physical shift. Similar phenomenon was reported for disparity- (Smith & Scott-Sammuel, 1998) and motion-defined (Maruya & Sato, 2001) MF patterns. In these stimuli, modulated features were derived from magno-pathway. In our study, we examined orientation-modulated MF patterns whose feature was derived from parvo-pathway and investigated higher-order motion perception based on first-order-like detectors. Our stimuli were made of orientation filtered random noise where no first-order artifact existed since source noise was replaced dynamically.
Method: The stimuli were 3.2 (V) × 9.7 (H) deg orientation-defined 0.15 cpd MF patterns generated by filtering random noise with Gabor filters (f=2.6cpd, sigma=0.21deg). Orientation of the Gabor filter was varied along horizontal axis following MF waveform between 0 to 90 deg. Stimuli were consisted of 5 motion frames. MF patterns were shifted 1/4 cycle between frames. Each frame was consisted of 8 temporal subframes (20ms) they were generated from different random noise with the identical orientation-modulation filter. ISI between motion frames was varied from 0 to 320ms. Subjects were asked to report the motion direction by 2AFC.
Results: Motion in the direction of shift was perceived for sinusoidal orientation-defined-motion patterns. For MF patterns, however, motion in the direction opposite to shift was dominant.
Conclusions: These results suggest that visual system detects higher-order motion in a similar way to that of regular first-order motion detectors in orientation-defined motion patterns. The present results suggested that higher-order motion system based on Fourier component like first-order detector is independent on modulated feature, even when original signal is derived from parvo-pathway.
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