title: Disparity biasing in depth from monocular occlusions.
abstract: Monocular occlusions have been shown to play an important role in stereopsis. Among other contributions to binocular depth perception, monocular occlusions can create percepts of illusory occluding surfaces. It has been argued that the precise location in depth of these illusory occluders is based on the constraints imposed by occlusion geometry. Tsirlin et al. (2010) proposed that when these constraints are weak, the depth of the illusory occluder can be biased by a neighboring disparity-defined feature. In the present work we test this hypothesis using a variety of stimuli. We show that when monocular occlusions provide only partial constraints on the magnitude of depth of the illusory occluders, the perceived depth of the occluders can be biased by disparity-defined features in the direction unrestricted by the occlusion geometry. Using this disparity bias phenomenon we also show that in illusory occluder stimuli where disparity information is present, but weak, most observers rely on disparity while some use occlusion information instead to specify the depth of the illusory occluder. Taken together our experiments demonstrate that in binocular depth perception disparity and monocular occlusion cues interact in complex ways to resolve perceptual ambiguity.
authors.affiliation: Centre for Vision Research, Department of Psychology, CSEB 0001, York University, 4700 Keele St., Toronto, Ontario, Canada. itsirlin@yorku.ca
authors.forename: Inna
authors.initials: I
authors.lastname: Tsirlin
authors.forename: Laurie M
authors.initials: LM
authors.lastname: Wilcox
authors.forename: Robert S
authors.initials: RS
authors.lastname: Allison
mesh_terms: D003463:Cues; D003867:Depth Perception / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology; D005556:Form Perception / Q000502:physiology; D006801:Humans; D009903:Optical Illusions / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology; D015357:Vision Disparity / Q000502:physiology*; D015349:Vision, Monocular / Q000502:physiology*