Abstract
The perceived color of a region can be influenced by spectral properties of adjacent areas, resulting in simultaneous color contrast. Color perception also depends on the chromatic properties of prior stimulation, a phenomenon known as color adaptation. The latter effect can result in a negative afterimage whose spectral properties are complementary to the chromatic properties of the prior stimulus. A positive afterimage is a secondary phenomenon resulting either from chromatic induction of a negative afterimage or from a negative afterimage produced by simultaneous contrast or from both. It has been demonstrated that perception of a positive afterimage can be strengthened by placing a solid contour around the area where the afterimage is perceived (Daw, Nature, 1962). This study explores secondary induction effects that result in a positive afterimage in combination with a neon color spreading in a region enclosed by an illusory boundary. Our experiments investigate the chromatic properties of that region over the lifetime of the afterimage. Participants were asked to evaluate the color of a figure perceived after superimposition of a neon color diamond over a diamond figure induced by a chromatic surround. The duration of presentation of the neon figure was systematically varied in order to probe the time course of chromatic integration. Our results demonstrate that the presence of an illusory boundary enhances the effect of the positive afterimage. While the positive afterimage is being perceived, the color of the illusory figure changes as a function of both the color of the surround that induces the afterimage and the neon color of the figural area. Chromatic integration occurs along the "mixture line" between the color of the positive afterimage and the neon color of the illusory figure.
Meeting abstract presented at VSS 2012