LUMINANCE NOISE AND THE RAPID-DETERMINATION OF DISCRIMINATION ELLIPSES IN COLOR DEFICIENCY

A computer-controlled test of; colour vision is described, in which lu minance noise and masking contours are used to ensure that the subject 's responses depend on chromatic signals. The test avoids the need-com mon to most computer-controlled tests-to define equiluminance for the individual subject before the colour test itself can be administered. The test achieves a good separation of protan and deutan subjects and reveals the large range of chromatic sensibilities among anomalous tri chromats. As a population, dichromats had higher thresholds on the tri tan axis of the test than did normals. In an extension of the test, fu ll discrimination ellipses were measured for normal and colour-deficie nt observers. The nature of anomalous trichromacy is discussed and the possibility is raised that hybrid genes, resulting from genetic recom bination, may code for incorrectly labelled or functionally impaired m olecules.