Color naming reveals our ability to distinguish between a colored background and colored light.

Objects appear to have much the same color under quite diverse illumination. This phenomenon, which is known as color constancy, can only be achieved by considering the color of surrounding surfaces. However, considering surrounding surfaces will yield errors if the chromaticity in such surfaces arises from the surface reflectance rather than from the illumination. Does the visual system treat chromaticity in the direct surrounding differently when it is evident that such chromaticity arises from the illumination than when it is evident that it arises from the surrounding surface reflectance? To investigate this, we briefly presented target patches on a simulation of a colorful ball rotating slowly under a lamp. Target patches were shown on differently colored surfaces, both under the lamp and in the shade. When naming the target patches' colors, surrounding colors had a larger influence on the named color when the simulated illumination was different than when the simulated reflectance of the surrounding surface of the ball was different. When matching the color rather than naming it, this distinction was only evident if the matching stimulus encouraged people to match the appropriate contrast. We propose that matching can reveal the sensed color, whereas naming reveals the interpretation in terms of surface reflectance.