The measurement and analysis of colour adaptation phenomena

Abstract

The phenomenon with which this paper deals is one that can be readily observed without any special apparatus at almost any time and is, indeed, familiar to all those concerned with visual matters, whether scientists, artists or others. Thus when the eye gazes at a patch of light for a short time the sensitivity of the eye is modified and the appearance of a coloured object will be changed from its normal appearance to an extent dependent on the nature of the initial patch of light. The object of the expeiments described below has been to measure such changes under various conditions: for different intensities and colour of the initial patch; for varying times of viewing this patch; and for a test object whose color and intensity is also variable; and finally to attempt to relate the results to the adaptation process and the three-colour response curves of the eye. Fig. 1 is a schematic diagram illustrating the action of the visual mechanism. To the left of H, a, b, c, d ,... represent the visible radiations of various wavelengths and amounts of energy, while to the right of H the diagram represents the visual chain leading to the brain. At some point P along this chain the visual response is divided into three independent paths A, B and C. Each of the raidations a, b, c, d , ... may have been modified into stimuli a′, b′, c′, d′ , .. but each radiation will still have its corresponding stimulus at P and each will, in general, contribute something to the three responses A, B, C.