Individual differences and their implications for color perception

Abstract

Individual differences are a conspicuous feature of color vision and arise from many sources, in both the observer and the world. These differences have important practical implications for comparing and correcting perception and performance, and important theoretical implications for understanding the design principles underlying color coding. Color percepts within and between individuals often vary less than the variations in spectral sensitivity might predict. This stability is achieved by a variety of processes that compensate perception for the sensitivity limits of the eye and brain. Yet judgments of color between individuals can also vary widely, and in ways that are not readily explained by differences in sensitivity or the environment. These differences are uncorrelated across different color categories, and could reflect how these categories are learned or represented.

Figure 1.

Individual differences in hue scaling (after [61]). a) 26 observers rated the perceived proportion of red, green, blue, or yellow in 36 stimuli spanning the cone-opponent plane. b) Hue scaling functions derived by converting the RGBY percents into a perceptual angle in a blue-yellow vs red-green plane, as a function of stimulus angle in the cone-opponent plane. Color lines are for for individual observers; black line plots the mean for all observers. c) Standard deviations across trials within an observer (dashed lines), or for the mean settings between observers (solid line). Between-subject differences are consistently larger suggesting they reflect real inter-observer differences in hue scaling rather than measurement noise. d) Factor analysis of the individual differences in the hue scaling functions identified 7 systematic factors, each accounting for the variance over a different narrow range of hues.