Connectionists: watercolor illusion and neon color spreading

[Stephen Grossberg]

The following article is now available at 
http://www.cns.bu.edu/Profiles/Grossberg

Baingio Pinna, and Stephen Grossberg (2005).
The watercolor illusion and neon color spreading: A unified analysis 
of new cases and neural mechanisms. Journal of the Optical Society of 
America A, in press.

ABSTRACT
Coloration and figural properties of neon color spreading and the 
watercolor illusion are studied using phenomenal and psychophysical 
observations. Coloration properties of both effects can be reduced to 
a common limiting condition, a nearby color transition called the 
"two-dot limiting case", that clarifies their perceptual similarities 
and dissimilarities. The results are explained by the FACADE neural 
model of   biological vision. The model proposes how local properties 
of color transitions activate spatial competition among nearby 
perceptual boundaries, with boundaries of lower contrast edges 
weakened by competition more than boundaries of higher contrast 
edges. This asymmetry induces spreading of more color across these 
boundaries than conversely. The model also predicts how depth and 
figure-ground effects are generated in these illusions.