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Frederick A. A. Kingdom, Nicolaas Prins; Different mechanisms encode the shapes of contours and contour-textures. Journal of Vision 2005;5(8):463. doi: 10.1167/5.8.463.
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© ARVO (1962-2015); The Authors (2016-present)
Aim. It is often assumed that curved contours, and textures made from parallel curved contours, are processed by the same mechanism. However, recent evidence from primate neurophysiology and brain-imaging studies suggests that contours and textures might be processed by different mechanisms. We used an adaptation paradigm to test whether the shapes of contours and contour-textures were encoded by the same or by different mechanisms. Method. Subjects adapted to pairs of sinusoidally-shaped contours or contour-textures. The two stimuli from each pair were an octave apart in shape frequency and presented above and below fixation. During the test phase, subjects indicated which of two test contours/contour-textures had the highest shape frequency, and an adaptive procedure found their PSE. Results. Adaptation to contours produced significant shifts in the perceived shape frequency of contours, but relatively little shift in the perceived shape frequency of contour-textures. Adaptation to contour-textures produced significant shifts in the perceived shape frequency of textures, but relatively little shift in the perceived shape frequency of contours. Conclusion. The shapes of contours and contour-textures are encoded by different mechanisms.
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