The Effects of Daylight and Tungsten Light-Adaptation on Color Perception*,†

A description is given of an apparatus which has been used to investigate how the color sensation corresponding to a given stimulus changes as the state of adaptation of the eye is altered.A limited series of results obtained with the apparatus reveals some very striking changes in color sensation as the adaptation is varied. Most colors appear much more saturated to the light-adapted eye than to the dark-adapted eye, and changes of hue also occur. The light-adapting radiations used were the I.C.I. standard illuminants, A and B, and their effects exhibited large differences.A few adaptation and recovery curves plotted against time are given, and indicate that photo-chemical rather than electrical processes are controlling the adaptation effects.The saturation effect is used to deduce a picture of retinal processes in the light- and dark-adapted states, and this is summarized in Table I and Fig. 11.A practical demonstration of the increase in saturation on light-adaptation can be seen in Fig. 12.