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Tatsuya Yoshizawa, Shunpachiro Tagami, Yasuto Tanaka, Tetsuo Kawahara, Haruyuki Kojima; Asymmetric effect of contrast on the size perception of Gabor patterns. Journal of Vision 2010;10(15):64. doi: 10.1167/10.15.64.
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© ARVO (1962-2015); The Authors (2016-present)
The visual psychophysics and the primate physiology have employed the Gabor function for a stimulus generation, because these patterns can be manipulated in spatial frequency and spatial domains independently. However, it has been known that Gabor patterns have some inconvenient characteristics. The size perception of the Gabor pattern depends on contrast. We investigated this phenomenon more in detail. Contrast discrimination threshold of the perceived size was measured between a test and a reference Gabor pattern (sigma=0.625 deg., 8 cpd-carrier). We varied contrast of the reference pattern from 10.0 to 80.0 % at four orientations (0, 45, 90, 135degrees) of the carrier component of the Gabor. Increment and decrement discrimination thresholds were measured in terms of the perceived size. Our results showed ambiguity of the determination of the size perception of the Gabor pattern, in accordance with those of the study by Fredericksen et al. (1997). Moreover, all thresholds increased as contrast of the reference pattern increased, and the function of the increment threshold was shallower than that of the decrement threshold. These results indicate that size perception differs between near threshold contrast and high contrast, suggesting asymmetrical interaction between size and contrast. We can model nonlinear properties of responses of the receptive field as to the increment and decrement contrast.
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