A bayesian observer replicates convexity context effects in figure-ground perception

Daniel Goldreich, Mary A. Peterson

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Peterson and Salvagio (2008) demonstrated convexity context effects in figure-ground perception. Subjects shown displays consisting of unfamiliar alternating convex and concave regions identified the convex regions as foreground objects progressively more frequently as the number of regions increased; this occurred only when the concave regions were homogeneously colored. The origins of these effects have been unclear. Here, we present a two-free-parameter Bayesian observer that replicates convexity context effects. The Bayesian observer incorporates two plausible expectations regarding three-dimensional scenes: (1) objects tend to be convex rather than concave, and (2) backgrounds tend (more than foreground objects) to be homogeneously colored. The Bayesian observer estimates the probability that a depicted scene is threedimensional, and that the convex regions are figures. It responds stochastically by sampling from its posterior distributions. Like human observers, the Bayesian observer shows convexity context effects only for images with homogeneously colored concave regions. With optimal parameter settings, it performs similarly to the average human subject on the four display types tested. We propose that object convexity and background color homogeneity are environmental regularities exploited by human visual perception; vision achieves figure-ground perception by interpreting ambiguous images in light of these and other expected regularities in natural scenes.

Original languageEnglish (US)
Pages (from-to)365-395
Number of pages31
JournalSeeing and Perceiving
Issue number3-4
StatePublished - 2012


  • Bayesian inference
  • Figure-ground
  • Gestalt principles
  • computational model
  • configural cue
  • natural scene statistics
  • object convexity
  • scene segregation

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Ophthalmology
  • Sensory Systems
  • Computer Vision and Pattern Recognition
  • Cognitive Neuroscience


Dive into the research topics of 'A bayesian observer replicates convexity context effects in figure-ground perception'. Together they form a unique fingerprint.

Cite this