A Psychophysical Study of White III Adaptation as Variant

Experimental data are presented which provide psychophysical specifications of white in terms of the stimulus variables, color temperature, and luminance, for 10 different adaptive conditions. A single test field size, 11.7°, and a single exposure time, 1 second, were used. The color temperatures of the adapting and surround illuminations were: 10,000°K, 7500°K, 5500°K, 4300°K, and 2842°K; and the adapting luminance levels were 5 and 15 mL. The white threshold contours exhibit minima in all cases, and vary systematically with both the color temperature and luminance of adapting and surround field. These variations are analyzed and discussed in terms of chromatic desensitization. Various principles and mechanisms of color vision are discussed in relation to the psychophysical functions presented in the three papers of this series. It is suggested that the properties exhibited by these functions are most simply interpreted by postulating an independent white mechanism. A summary is presented of the three papers constituting the series.