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Armando Bertone, Jocelyn Faubert; The interactive effects of symmetry and binocular disparity on visual surface representation. Journal of Vision 2002;2(7):94. doi: 10.1167/2.7.94.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. In order to recognize an object in our environment, we must first create a representation of its visual surface. Visual surface representation implicates the encoding and grouping of image attributes belonging to a same surface. The purpose of the study was to investigate the effects of bilateral symmetry and binocular disparity on the perception of a visual surface and how these two image features interact with each other. Methods. Exp. 1: Symmetrical dot patterns were presented to 3 observers with both halves of the pattern on either the same or different depth planes (disparity: 60.4 and 122.9 sec arc) for 250 msec. A 2ATFC constant stimuli procedure was used to measure symmetry detection thresholds (% matching dots) at each level of disparity. Exp. 2: Using the same procedure as Experiment 1, depth detection thresholds were measured at 4 levels of disparity (0, 30.1, 60.4, and 122.9 sec arc) for different levels of symmetry (6.25, 12.5, 25, 50, 75 & 100 % matching dots). Results. Exp. 1: Symmetry detection thresholds increased as a function of binocular disparity for all three observers. Exp. 2: The amount of symmetry in the pattern did not have an effect on the observers' ability to identify depth for any of the 4 levels of disparity. Conclusions. Under the specific stimulus parameters used, results suggest that depth created by disparity is a more predominant image attribute than is symmetry for visual surface representation. We are presently assessing whether manipulating certain temporal parameters (i.e., stimulus exposure duration) affects this predominance.
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