Effect of Distance on Heterochromatic Matching

Abstract

The brightness of colors in a number of paintings by Francis Pratt appeared to vary as a function of the viewing distance. These pictures were composed of narrow strips of different colors varying in brightness and saturation. Five experiments were undertaken to replicate and study this effect under controlled conditions using heterochromatic brightness matching of various pairs of colored stimuli. The subjects were first-year students in psychology, participating as a course requirement. The number of subjects varied in the different experiments, between 6 and 9. The relative brightness of blue as compared to red, orange, and yellow-green varied as a function of viewing distance. The relative brightness of the blue decreased as distance increased. By varying the physical size of the stimuli it was possible to keep the angle subtended at the retina constant for two distances and the effect remained. Any explanation must therefore account for the finding that the effect is not due to the apparent size of the stimuli.