Influence of chromatic properties of background on color constancy for a two-dimensional stimulus

We investigated how the chromatic properties of background surfaces affect color constancy using two-dimensional stimuli in a haploscopic view. The reference and test stimuli, illuminated by D65 and chromatic illuminants (red, green, blue, and yellow), consisted of a central 1.2° test patch, a 4.2° Mondrian-like background, and a peripheral 0.4° gray fringe. We used the neutral background and chromatic red-, green-, blue-, and yellow-dominated backgrounds, in which these patch colors were systematically shifted to one color direction while keeping the hue circle. In the first two conditions, both the reference and test feature the same background (neutral and complementary to the illuminant color). In contrast, in the last two conditions, the reference and test stimuli feature different backgrounds, and the expected color appearance of the backgrounds, except at the fringe, looks similar (the color of the illuminant and neutral). The results showed a notable decline in color constancy in the last two conditions, suggesting that the effectiveness of adaptation and illuminant estimation is reduced by the smaller stimulation difference between the reference and test, as well as by the unexpected spatial color structure, even though the cue itself still exists.