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Andrea Li, Belinda Tzen, Alevtina Yadgarova, Qasim Zaidi; 3D curvature aftereffects from illusory orientation flows. Journal of Vision 2006;6(6):256. doi: 10.1167/6.6.256.
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© ARVO (1962-2015); The Authors (2016-present)
In perspectival images of textured surfaces, veridical 3D curvatures are conveyed by specific patterns of orientation flows (Li & Zaidi, 2004, 2001, 2000). In Kitaoka's illusion Zabuton, 3D shapes are conveyed by illusory orientation flows: straight horizontal and vertical edges of a checkerboard pattern appear curved because of high contrast interstices. We used concave and convex Zabutons (2 sec) in an adaptation paradigm to establish whether 3D aftereffects can be explained by adaptation of local luminance mechanisms, independent or laterally-interactive orientation selective mechanisms, or 3D-curvature selective neural mechanisms. After adaptation, observers judged shape aftereffects as concave or convex for three types of flat checkerboard tests (200 msec): in-phase with the adapting checkerboard, opposite-phase, or phase-shifted by half-cycles in both dimensions. Local luminance gain controls predict that the aftereffect should be opposite to the adapting curvature for the in-phase test, same as adapting curvature for the opposite-phase test, and flat for the phase-shifted test. Adaptation of independent local orientation mechanisms predicts flat percepts for all of the test stimuli because the adapting orientations are physically horizontal and vertical. Adaptation of laterally-interactive orientation selective mechanisms influenced by the effects of the interstices predicts opposite curvature aftereffects for the in-phase and opposite-phase tests, but flat percepts for the phase-shifted tests. Adaptation of 3D-curvature selective mechanisms predicts opposite curvature aftereffects regardless of the test phase. Preliminary results are consistent with the adaptation of 3D-curvature selective mechanisms that that are invariant to exact placement of contours in the receptive field.
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