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Ko Sakai, Takeshi Oyakawa; Simultaneous Representation of Shape and Material --- Adaptation to Material Alters the Perception of Depth ---. Journal of Vision 2016;16(12):635. doi: 10.1167/16.12.635.
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© 2017 Association for Research in Vision and Ophthalmology.
The human visual system infers simultaneously surface reflectance, object shape, and lighting from an image projected onto the retina. It remains to be clarified how the visual system solves this ill-posed problem. To approach this problem, we investigated whether the visual system represents simultaneously material qualities and object depth. Specifically, we examined whether the adaptation to a specific material alters the perceptual depth of an object that consisted of the material. If the adaptation to a material alters the perceptual depth, simultaneous representation of material quality and object depth is suggested. This will lead to a prediction that a neuron, or a neural circuit, is co-selective to material and depth. To test the hypothesis, we rendered high-dynamic-range images of a bumpy surface with a specific reflectance/material (Bidirectional Reflectance Distribution Function). A pair of the images was presented simultaneously for adaptation, with their BRDFs far apart in the perceptual gloss space (Contrast gross & Distinctness-of-image gloss). The degrees of bumpiness were adjusted so that their perceptual depth was identical. For test, we presented another pair of stimuli with the BRDF in-between those used in the adaptation. Each stimulus had distinct depth of bumps, and participants were asked to judge which surface appeared deeper (constant stimuli method). The results showed the significant difference in the perceptual depth between the pre- and post-adaptation, indicating that the adaptation to material suppressed the perception of depth. We obtained similar results in the control experiment in which the matte stimulus was replaced by the synthesized stimulus (Portilla & Simoncelli, 2000) so that early-level features were identical with the gloss stimulus but apparent material was matte, denying the adaptation to early-level features. The present results support the hypothesis that the visual system represents simultaneously shape and material.
Meeting abstract presented at VSS 2016
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