title: Size matters: Perceived depth magnitude varies with stimulus height.
abstract: Both the upper and lower disparity limits for stereopsis vary with the size of the targets. Recently, Tsirlin, Wilcox, and Allison (2012) suggested that perceived depth magnitude from stereopsis might also depend on the vertical extent of a stimulus. To test this hypothesis we compared apparent depth in small discs to depth in long bars with equivalent width and disparity. We used three estimation techniques: a virtual ruler, a touch-sensor (for haptic estimates) and a disparity probe. We found that depth estimates were significantly larger for the bar stimuli than for the disc stimuli for all methods of estimation and different configurations. In a second experiment, we measured perceived depth as a function of the height of the bar and the radius of the disc. Perceived depth increased with increasing bar height and disc radius suggesting that disparity is integrated along the vertical edges. We discuss size-disparity correlation and inter-neural excitatory connections as potential mechanisms that could account for these results.
authors.affiliation: Centre for Vision Research, Department of Psychology, York University, 4700 Keele St., Toronto, Ontario, Canada; Eye Movement and Neuroscience Laboratory, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada. Electronic address: inna.tsirlin@sickkids.ca.
authors.forename: Inna
authors.initials: I
authors.lastname: Tsirlin
authors.affiliation: Centre for Vision Research, Department of Psychology, York University, 4700 Keele St., Toronto, Ontario, Canada.
authors.forename: Laurie M
authors.initials: LM
authors.lastname: Wilcox
authors.affiliation: Centre for Vision Research, Department of Electrical Engineering and Computer Science, York University, 4700 Keele St., Toronto, Ontario, Canada.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Allison
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003867:Depth Perception / Q000502:physiology*; D006801:Humans; D010775:Photic Stimulation / Q000379:methods; D012684:Sensory Thresholds; D012858:Size Perception / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology
keywords: Depth perception; Disparity; Energy model; Size–disparity correlation; Stereopsis