Abstract
The degree to which color constancy holds can be estimated by various methods. Categorical color naming is one we used to reveal categorical nature of color constancy (Uchikawa et al., 2002, J. Vision, 2(7), 548a). In the present study we compared categorical color naming with asymmetric color matching in order to clarify whether these two methods yield different degrees of color constancy. In the categorical color naming procedure a liquid crystal projector (LCP) illuminated an OSA test color chip (5deg × 5deg) and the gray surround (50deg × 40deg). The observer named the test color using one of the Berlin-Kay 11 basic color names. The test illuminants were 6500K, 3000K and the LCP Red phosphor (nearly 1000K). In the asymmetric color matching procedure the observer dichoptically viewed the test illumination (left) and the reference (6500K) illumination (right) sides of the booth. A test color chip (L=0 or 1), named gray or white under the test illumination in the categorical color naming, was placed in the test side. A matching color chip (L=0, j=0, g=0), illuminated with a spotlight separately from the surround 6500K white, was placed in the reference side. This spotlight illumination made it possible to equivalently vary surface color of the matching color chip so that the observer adjusted its color appearance to be matched with the test color appearance. We found that the categorically named achromatic color chips under the strong red light (LCP Red) were mostly matched to the chromatic color chips under the white light. This means that categorical color constancy is not explained by color appearance, but holds in a wider range of illumination.