Colour blindness: a comparison of different methods of testing colour blindness

The study of colour-blindness has been somewhat retarded by the concomitant study of colour theories. The majority of investigators have started out unduly biased by their favourite theory and have examined colour-blinds from this prejudiced standpoint. The result is that great deal of unnecessary confusion has gathered round this subject which has ultimately caused an obscuring of the real issues. Attempts have been made from time to time to get from theories but on the whole these have proved futile and the results achieved are only gradually permeating the literature of the subject. Yet even in the highest authoritative references to colour-blindness, it is amazing to find that a description of the defect is inevitably given along the lines of some particular theory, although it must be admitted that some authors take the precaution of inserting a note to the effect that such a description holds only if the theory be accepted