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Yong R. Su, Teng Leng Ooi, Zijiang J. He; Representing grating-texture surface begins with spreading of grating-texture from the surface boundary contour. Journal of Vision 2010;10(7):1180. doi: 10.1167/10.7.1180.
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© ARVO (1962-2015); The Authors (2016-present)
Research on color filling-in suggests the visual system represents a homogeneous surface by first coding the surface boundary contours and then filling-in the interior with the surface feature (color). Here, we investigated if texture surfaces are similarly represented. A trial began with the presentation of a vertical grating display (4 cpd, 4.14 x 4.14 deg). After 200 msec, a rectangular region (length = 2.67 deg) with horizontal grating (4 cpd) was added onto the central area of the vertical grating display. The upper and lower boundary contours of the rectangular region were blurred with a Gaussian kernel (FWHM = 0.6 deg), leaving only the right and left boundary contours with sharp edges. This rectangular region was presented for 30, 50, 100, 150, 200, 250, or 500 msec. Observers were instructed to judge the proportion of the central area of the rectangular region not filled with the horizontal grating, and report the proportion based on a rating scale from 0 to 6. A scale of “0” indicates the entire length of the rectangular region being filled with horizontal grating, whereas “6” indicates no horizontal grating being seen in the entire rectangular region. It is predicted if the representation of the rectangular region begins with the horizontal grating spreading from the boundary contours, the rated number (proportion of the central area not filled with horizontal grating) will decrease with increasing stimulus duration. Confirming the prediction, we found the area of the rectangular region represented by horizontal grating texture increased with stimulus duration. We further fitted our data according to the cortical magnification factors in areas V1 and V2, and found the average grating spreading speeds were relatively constant at 49.5 and 78.3 cm/s, respectively. Thus, our study underscores the important role of boundary contours in representing texture surfaces.
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