ABSTRACT
Abstract-We investigated perception of symmetry by measuring the ability of the visual system to detect small amounts of asymmetry. Our vertically symmetric stimulus prototypes were perturbed by scaling one of the half planes relative to the other. Using stimuli composed of small dots, we determined that the visual system detects symmetries using multiple spatial scales. In particular, symmetry can be computed from the position of individual dots, but the performance is improved if the dots form larger features such as lines and corners. Our data suggest that curved lines might be less effective than straight lines. We also found that symmetry of 1 deg patterns can be perceived in the parafovea more accurately than would be expected from the results of prior bisection and hyperacuity experiments. Finally, we determined that the luminance distribution may affect estimates of the axis of symmetry. We discuss a feasible model of symmetry perception based on a multiresolution representation, such as the cortex transform proposed by Watson (1987).
