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Lars Strother, Kyle Killebrew, Gideon Caplovitz; The Lemon-Illusion: Seeing curvature where there is none. Journal of Vision 2015;15(12):329. doi: 10.1167/15.12.329.
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© 2017 Association for Research in Vision and Ophthalmology.
Curvature is a highly informative visual cue for object recognition. We present a novel illusion—the Lemon Illusion—in which subtle illusory concavities are perceived in the absence of actual curvature. We offer several perceptual demonstrations that show when the illusion does or does not occur. Based on some of our observations, and the large body of research on the role of curvature in the visual perception of object shape, we conclude that the Lemon Illusion likely arises due to the reconciliation of contour curvature interpolation and explicit zero-curvature contour. The observations are consistent with two non-mutually exclusive neural mechanisms within visual cortex that could account for the Lemon Illusion. The first involves curvature-continuation mechanisms such as those thought to subserve contour integration as early as V1 and V2. The second involves global shape processing within V4.
Meeting abstract presented at VSS 2015
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