The Locus of Unique Green in Deuteranomalous Trichromats

A method of color naming was used to determine the spectral locus for unique green (UG) as it was perceived by 20 color normals and 24 deuteranomalous trichromats. The loci for the normal group were distributed bimodally, as earlier investigators had reported, and a bimodal distribution was also found for the deuteranomalous group. In the latter group, UG was located at long wavelengths only by those who had been classified as mild deuteranomals according to several clinical criteria. Those who located UG at shorter wavelengths included individuals whose defects ranged from mild to severe. This result is discussed in the context of theories of deuteranomaly and is presented as further evidence for the existence of 2 types of deuteranomaly.