Some Experiments on the Trichromatic Theory of Vision

A repetition of an investigation carried out by Wright in 1934 is made with an improved design of the Wright trichromatic colorimeter. The technique is described and the assumptions in the method for determining the fundamental response curves discussed. New observations are reported in which the generalized form of von Kries's law of coefficients is found to break down, and the departures from the coefficient law are analysed. Possible physiological causes for the breakdown are discussed. By a modification in the calculations, a new attempt has been made to locate the colours in the trichromatic colour chart corresponding to the three fundamental responses, and to derive the response curves. Calculations were first made in the W. D. Wright trichromatic system and were transformed into the rectangular uniform chromaticity scale system of Breckenridge & Schaub, showing the caution required in interpreting the statistical spread of the results.