The contribution of local variations in hue or contrast to symmetry of things in a thing

TL;DR

This study investigates how local color and contrast variations affect the perception of symmetry in shapes, revealing that such variations increase perceptual uncertainty and influence decision-making speed in humans.

Contribution

It demonstrates that local hue and contrast variations significantly impact symmetry perception, highlighting their functional role in visual processing.

Findings

Color and contrast variations slow down symmetry detection responses.

Local variations increase stimulus uncertainty in symmetry perception.

Symmetry detection is sensitive to chromatic and contrast disturbances.

Abstract

Symmetry contributes to processes of perceptual organization in biological vision and influences the quality and time of goal directed decision making in animals and humans, as discussed in recent work on the examples of symmetry of things in a thing and bilateral shape symmetry. The present study was designed to show that selective chromatic variations in geometric shape configurations with mirror symmetry can be exploited to highlight functional properties of symmetry of things in a thing in human vision. The experimental procedure uses a psychophysical two alternative forced choice technique, where human observers have to decide as swiftly as possible whether two shapes presented simultaneously on a computer screen are symmetrical or not. The stimuli are computer generated 2D shape configurations consisting of multiple elements, with and without systematic variations in local color, color saturation, or achromatic contrast producing variations in symmetry of things in a thing. All stimulus pairs presented had perfect geometric mirror symmetry. The results show that varying the color of local shape elements selectively in multichromatic and monochromatic shapes significantly slows down perceptual response times, which are a direct measure of stimulus uncertainty. It is concluded that local variations in hue or contrast produce functionally meaningful variations in symmetry of things in thing, revealed here as a relevant perceptual variable in symmetry detection. Disturbance of the latter increases stimulus uncertainty and thereby affects the perceptual salience of mirror symmetry in the time course for goal relevant human decisions.