Use of a Monochromatic Colorimeter for the Study of Color Blindness

A method and apparatus are described which make it possible to classify accurately defective color vision and to study the limens, with regard to shape, size, and orientation, of any observer. The instrument, which is described in detail, employs the principle of monochromatic colorimetry. The experimental arrangement is such that instrumental readings may be plotted directly upon the I.C.I. chromaticity diagram, so that the limens may be explored during the period of actual testing. Limens have been obtained for seven observers and for five colors distributed around the chromaticity diagram. The limens are characteristic of the observer, and those established for the several observers exhibit large and interesting differences. One observer was found to be a deuteranope, two were anomalous trichromats in significantly different degrees, and the remaining four observers having "normal" color vision were found to differ appreciably in their limens. The method, which is too slow for routine testing, would seem to be of value in fundamental studies of both normal and abnormal color vision, and in the testing of observers whose occupations involve possible loss of life or valuable property through incorrect color discrimination. Some practical implications are discussed.