Abstract
Symmetry is a significant factor for deriving the direction of figure. Although symmetry is common among both biological shapes and artificial objects, and known as a Gestalt factor, few studies have quantified its nature and analyzed the function quantitatively. We focus on symmetry in contours of natural images, and establish a geometrical index that describes the degree of symmetry (DoS) inherent in arbitrary contour. To examine whether DoS matches with the perception of symmetry, we carried out psychophysical experiments. The results showed a good agreement between the perception of symmetry and DoS where the participants showed confidence/consistency in the perception, indicating that DoS reflect the perception of symmetry and that perception of symmetry depends surely on the geometrical degree of symmetry.
