The Neon Color Spreading and the Watercolor Illusion: Phenomenal Links and Neural Mechanisms

Abstract

This work explores the interactions between the cortical boundary and coloration and figural properties of two illusions: the neon color spreading and the watercolor effect. Through psychophysical and phenomenal observations the neon color spreading has been compared with the watercolor illusion. The results showed that the phenomenal qualities of both effects can be reduced to a basic common limiting case that can explain the perceptual differences between the two illusions. Finally, the article proposes a unified explanation of the properties of the two illusions in terms of the FACADE neural model of biological vision (Grossberg, 1994). The model clarifies how local properties, such as spatial competition, can control some properties of both illusions, and how more global figural properties, determining the shape and strength of contours, can explain differences between the two illusions.