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Hiroaki Shigemasu, Mitsuhiro Yoshida, Michiteru Kitazaki; Local binocular depth contrast effects on surface edges. Journal of Vision 2009;9(8):272. doi: https://doi.org/10.1167/9.8.272.
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© ARVO (1962-2015); The Authors (2016-present)
Many studies have shown that binocular depth contrast is related to global processing of disparities. In contrast, there have been few studies demonstrating local depth contrast of surfaces analogous to that of luminance domain. In this study, we demonstrate local interaction in depth by placing a depth gap adjacent to a curved depth surface. Test stimuli were horizontally oriented convex/concave cylindrical surfaces. Two planar surfaces (inducer) were placed adjacent to the above and below curved edges of test stimuli with crossed/uncrossed disparity. The results showed that a convex surface placed next to an inducer with uncrossed disparity had a flatter appearance while concave surface had a flatter appearance with an inducer having crossed disparity. To demonstrate that the effects were caused by local edge interaction, we used two other types of inducers. First, we placed the inducers adjacent to the right and left edges of test stimuli. The results showed much less flattening effects, suggesting that the effects were not caused only by the depth position of the inducers but by the local depth contrast. Second, we used inducers whose depths were vertically alternated with square wave oscillation. The disparities of inducers adjacent to the edge of test stimuli were either crossed or uncrossed. If depth contrast effects occur only globally, there should be no effect of local depth position adjacent to test stimuli because the average disparities of inducers were both zero. If the effects are local, they should depend on the depth position of the inducer adjacent to test stimuli. The results showed that a convex surface had a flatter appearance when an inducer was behind at the edge of test stimuli while concave surface was flattened when inducer was in front. These results also suggest that there is a local depth contrast effect in depth domain.
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