Mirror Symmetry Perception: The Effect of Proximity to the Central Axis

The detection of environmental regularity is a fundamental process in visual perception. One way of increasing our understanding of the visual system is by modelling the performance of human observers on tasks in which they are required to detect visual regularities such as bilateral symmetry. Past research has indicated that there is a perceptual advantage for symmetry information located immediately adjacent to the central axis (Barlow & Reeves, 1979; Rainville & Kingdom, 2002), but it has been unclear whether this was due to the temporal or spatial properties of the stimulus. Three potential outcomes were hypothesised in relation to a symmetry detection task and Bayesian model selection was used to determine which outcome best accounted for the empirical data. Results indicate that when temporal limitations are removed the perceptual advantage remains, suggesting that it is due (at least in part) to the spatial properties of symmetrical stimuli. The research reported in this paper was conducted at the University of Adelaide.