title: The influence of object size and surface shape on shape constancy from stereo.
abstract: The failure of shape constancy from stereoscopic information is widely reported in the literature. In this study we investigate how shape constancy is influenced by the size of the object and by the shape of the object's surface. Participants performed a shape-judgment task on objects of five sizes with three different surface shapes. The shapes used were: a frontoparallel rectangle, a triangular ridge surface, and a cylindrical surface, all of which contained the same maximum depth information, but different variations in depth across the surface. The results showed that, generally, small objects appear stretched and large objects appear squashed along the depth dimension. We also found a larger variance in shape judgments for rectangular stimuli than for cylindrical and ridge-shaped stimuli, suggesting that, when performing shape judgments with cylindrical and ridge-shaped stimuli, observers rely on a higher-order shape representation.
authors.affiliation: Department of Psychology, University of Glasgow, 58 Hillhead Street, Glasgow G12 8QB, Scotland, UK.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Champion
authors.forename: David R
authors.initials: DR
authors.lastname: Simmons
authors.forename: Pascal
authors.initials: P
authors.lastname: Mamassian
mesh_terms: D003867:Depth Perception / Q000502:physiology; D006801:Humans; D007600:Judgment; D008433:Mathematics; D010364:Pattern Recognition, Visual / Q000502:physiology; D011581:Psychological Tests; D012858:Size Perception / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D013499:Surface Properties