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Ö. Dağlar Tanrıkulu, Vicky Froyen, Lynn Ma, Jacob Feldman, Manish Singh; Combination of contour convexity and accretion/deletion in the perception of relative depth. Journal of Vision 2014;14(10):62. doi: 10.1167/14.10.62.
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© ARVO (1962-2015); The Authors (2016-present)
Accretion/deletion is widely considered a reliable cue to depth ordering, with the accreting/deleting surface perceived as behind the adjoining surface. However, Froyen et al. (2013, JoV) showed that when accretion/deletion occurs on both sides of a contour, the resulting ambiguity in depth ordering can be resolved by geometric figure-ground cues such as convexity. Specifically, convex accreting/deleting regions were perceived as in front and as self-occluding due to rotation in 3D, despite the constant speed profile. Tanrikulu et al. (2013, VSS) further showed that the perception of 3D rotation can also occur when only one side of a border had accreting/deleting texture, which contradicts traditional interpretations of accretion/deletion. Here we examine how convexity and accretion/deletion combine. Our displays contain alternating light and dark regions with random dots moving horizontally at constant speed, but in opposite directions in alternating regions. We manipulated relative strength of convexity and relative texture density in the two sets of regions. Convexity was manipulated quantitatively, ranging from unbiased to strongly biased (i.e., with sharper negative minima of curvature on one side). Relative texture density was manipulated so that it either cooperated or conflicted with the convexity cue. Subjects reported which set of regions was seen as a single sheet translating in the background. Increasing the degree of convexity in a region made it more likely to be perceived as figural, whereas increasing the density of the accreting/deleting texture made it less so. However, convexity exerted a stronger influence on figural status, while the effect of texture density was only prominent when convexity was weak. Our results show that, even moderate levels of convexity can override standard depth from accretion-deletion. These findings cannot be explained by traditional accounts of depth-from-motion, and point to a deeper interaction between contour geometry and dynamic cues than has previously been appreciated.
Meeting abstract presented at VSS 2014
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