Annual Meeting of the Psychonomic Society edition:50 location:Boston date:20-22 November 2009
Since the early observations by Ernst Mach (1886), vertical mirror symmetry has been assumed to play a key role in perceptual organization. However, no empirical studies have reported a benefit of symmetry in figure–ground organization.
In a two-alternative forced choice design, we asked participants to indicate which of two Gabor arrays contained a visual shape. The shape, defined by a subset of Gabor patches aligned with the shape outline, was either symmetric or asymmetric, but no symmetry judgment was required. The saliency of the embedded shape was reduced by adding orientation noise to the Gabor patches. Across different noise levels, symmetric shapes were more detectable than asymmetric shapes. This suggests that symmetry does act as a cue in figure–ground segregation.
A posteriori analyses on the amount of symmetry in our stimuli further support this finding.