Figure 5.

Comparison of standard color contrast (A) and more complex scenes which provide spectral cues that either increase (B) or decrease (C) the probability that the two arrays are differently illuminated. Using the “buttons” provided, the subjects' task was to adjust the apparent hue (H), saturation (S), and brightness (B) of the targets in comparison boxes below the stimulus until the colors in the comparison boxes matched the apparent colors of the corresponding targets in the test scene. The adjusted targets were presented below the scenes to preserve the empirical significance of the arrays. The differences in these adjustments are shown in D. The values given represent the average responses of the two authors and eight naive subjects to the stimuli indicated; all differences are statistically significant (P < 0.01).