Abstract
Introduction: False Colors, studied by Fechner and popularized by Benham’s top, are now generally referred to as pattern-induced flicker colors (PIFCs). We compared designs of Benham’s tops using a color-matching methodology to characterize PIFCs for normal versus colorblind individuals. We hypothesized and confirmed that both populations generally perceive at most four principal colors, but colors for colorblind are less numerous and less saturated. We also hypothesized and confirmed that PIFCs are more saturated when using clear designs compared to blurry, and under monochromatic lighting compared to broadband white lighting. Methods: We spun disks at 300 rpm, and compared three designs, with either clear or blurry edges, and monochromatic versus broadband white lighting. Viewers indicated which colors they perceived by comparing a panel of Color-Aid Corp squares of various hue and saturation. Results: Number and saturation of perceived colors varied by condition with a ceiling of four prototypical colors. The classic Benham’s top design produced the most saturated PIFCs. For normal viewers, mean number of PIFCs exceeded 3 for the best, clear design under optimal red monochromatic lighting. This decreased by about ½ when the pattern was blurred, another ¼ with less effective designs, and another 3/2 under broadband white lighting. Chosen saturation levels followed the same trends. Colorblind individuals exhibited a similar pattern with an average of about 1 less color and less saturation, and their optimal lighting condition moved toward blue, with reported PIFCs generally shifted away from red. Discussion: We found both normal and colorblind individuals exhibited a ceiling of four false colors that corresponds to the prototypical opponent-process colors of Red, Orange-Yellow, Green, and Blue-Violet, with number and saturation decreasing under various conditions. The pattern of IFPCs is consistent with opponent-process physiology. The False Color phenomenon may provide an alternative method of displaying color for specialized displays.