The characteristics of protanomalous vision

The colour vision of 11 protanomalous observers, selected from about 2,000 persons, has been tested in detail. The measurements include the luminosity curve, the mixture curves, the trichromatic coefficients through the spectrum, the hue discrimination curve and the saturation discrimination curve. The observers have been arranged in order of increasing seriousness of the defect, and the hue discrimination results yield a family of curves ranging between that for the normal trichromat and that for the protanopic type of dichromat. The luminosity data, on the other hand, vary little from observer to observer and the mean curve is almost identical with that of the protanope in the red-yellow-green region of the spectrum. This result is difficult to reconcile with the ordinary conception that different degrees of protanomalous defect arise from the magnitude of the red response varying from one observer to another.