Chromatic Adaptation*

The dependence of corresponding colors on different chromatic adaptations has been studied by a method of local adaptation. Both eyes were exposed simultaneously to the same colors. Observations of one second duration were alternated with adaptation periods of nine seconds duration. Differenta dapting colors appeared in the two halves of a simple colorimeter field, which had a vertical dividing line. The observer kept his gaze fixed upon the center of that line. He then adjusted the colorimeter which produced the color which replaced the adaptation color in one half of the field, so that during the one-second observation it appeared to match the color which replaced the other adapting color. The colors which appeared to match under these conditions were compared with the predictions of Von Kries's trireceptor coefficient law. Various modifications of that law were tried. Systematic discrepancies from predictions of laws of this form were analyzed. An hypothesis of five different receptors whose responses are merged onto three channels in the nervous system was found adequate to account for almost all of the experimental findings. The presence of a sixth different adapting process in the retina was indicated in one case.