The Biological Basis of the Experience of Constant Colour Categories

In the work reported here, we used the Land Color Mondrian experiments to test the degree to which subjects vary in their perception of color categories. Twenty subjects of different ethnic and cultural backgrounds, for all but one of whom English was not the primary language, viewed 8 patches of different color in two Mondrian displays; each patch, when viewed, was made to reflect identical ratios of long, middle and short wave light. Subjects were asked to match the color of the viewed patch with that of the Munsell chip coming closest in color to that of the viewed patch, without using language. Overall, there was no variability in categorizing colors as red, yellow, brown and green but a small variability in categorizing them as purple, blue, orange and turquoise. In terms of hue, we found significantly less variability in matching warm hues than in cool ones. We interpret the lack of significant variability between subjects in the matches made as a pointer to similar computational mechanisms being employed in different subjects to perceive colors, thus permitting subjects to assume that their categorization of colors has universal agreement and assent.