title: The role of color and attention-to-color in mirror-symmetry perception.
abstract: The role of color in the visual perception of mirror-symmetry is controversial. Some reports support the existence of color-selective mirror-symmetry channels, others that mirror-symmetry perception is merely sensitive to color-correlations across the symmetry axis. Here we test between the two ideas. Stimuli consisted of colored Gaussian-blobs arranged either mirror-symmetrically or quasi-randomly. We used four arrangements: (1) 'segregated' - symmetric blobs were of one color, random blobs of the other color(s); (2) 'random-segregated' - as above but with the symmetric color randomly selected on each trial; (3) 'non-segregated' - symmetric blobs were of all colors in equal proportions, as were the random blobs; (4) 'anti-symmetric' - symmetric blobs were of opposite-color across the symmetry axis. We found: (a) near-chance levels for the anti-symmetric condition, suggesting that symmetry perception is sensitive to color-correlations across the symmetry axis; (b) similar performance for random-segregated and non-segregated conditions, giving no support to the idea that mirror-symmetry is color selective; (c) highest performance for the color-segregated condition, but only when the observer knew beforehand the symmetry color, suggesting that symmetry detection benefits from color-based attention. We conclude that mirror-symmetry detection mechanisms, while sensitive to color-correlations across the symmetry axis and subject to the benefits of attention-to-color, are not color selective.
authors.affiliation: University of Stirling, Department of Psychology, Stirling, FK9 4LA, Scotland, United Kingdom.
authors.forename: Elena
authors.initials: E
authors.lastname: Gheorghiu
authors.affiliation: McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Canada.
authors.forename: Frederick A A
authors.initials: FAA
authors.lastname: Kingdom
authors.affiliation: University of Stirling, Department of Psychology, Stirling, FK9 4LA, Scotland, United Kingdom.
authors.forename: Aaron
authors.initials: A
authors.lastname: Remkes
authors.affiliation: Kwangwoon University, Department of Industrial Psychology, Seoul, Korea.
authors.forename: Hyung-Chul O
authors.initials: HO
authors.lastname: Li
authors.affiliation: VizirLabs Consulting, Chelsea, Quebec, Canada.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Rainville