July 2013
Volume 13, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   July 2013
Surprising Evidence of Competition in a Classic Figure-Ground Stimulus Supports a Role for Background Priors in Figure Assignment
Author Affiliations
  • Mary A Peterson
    Psychology Department and Cognitive Science Program, School of Mind, Brain, and Behavior, University of Arizona
  • Elizabeth Salvagio
    Psychology Department and Cognitive Science Program, School of Mind, Brain, and Behavior, University of Arizona
Journal of Vision July 2013, Vol.13, 717. doi:10.1167/13.9.717
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      Mary A Peterson, Elizabeth Salvagio; Surprising Evidence of Competition in a Classic Figure-Ground Stimulus Supports a Role for Background Priors in Figure Assignment. Journal of Vision 2013;13(9):717. doi: 10.1167/13.9.717.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Figure-ground organization entails competition between objects that might be perceived on opposite sides of borders. Some displays don’t seem to involve competition because agreement regarding the final percept is nearly unanimous. For instance, ~90% of observers report perceiving convex regions as figures in the eight-region black-and-white displays with alternating convex/concave regions that the Gestaltists used to demonstrate that convexity is a figure prior. Recently, Peterson and Salvagio (2008) showed that p(convex=figures) is high in unmasked 8-region displays exposed for 100 ms, provided that the concave regions are homogeneously colored. To model these results, Goldreich and Peterson (2012) assumed that perceiving convex regions as figures entails interpreting the concave regions as portions of a background surface, which occurs when they are homogeneously colored, on the prior that single surfaces tend to be a single color. Their model makes the surprising prediction that a background surface interpretation is considered for homogeneously-colored convex regions as well, and hence, that foreground and background interpretations for homogeneous convex regions compete before figure assignment occurs. Because competition takes time, evidence that it takes longer to perceive convex regions as figures in displays with homogeneous rather than heterogeneous convex regions would support the hypothesized competition. We tested this prediction by masking 100-ms displays immediately or 50-ms later. P(convex=figure) was larger for displays with heterogeneously- than homogeneously-colored convex regions in both display-mask SOA conditions, p<.01. With a display-mask SOA of 150 ms, p(convex=figure) for heterogeneous convex displays was 85%, whereas p(convex=figure) for homogeneous convex displays did not reach 85% even with display-mask SOAs of 300 ms. Investigating the time course of figure assignment supports a model positing a role for background priors as well as figure priors and reveals that a classic demonstration of the convex figures prior is surprisingly ambiguous.

Meeting abstract presented at VSS 2013

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