Color perception in observers with varying photopigment opsin genotypes

In 1981, Nagy, MacLeod, Heyneman, and Eisner published an empirical investigation entitled “Four cone pigments in women heterozygous for color deficiency” showing failures of additivity of trichromatic matches for some heterozygous women, and suggesting the eyes of such women contained more than three types of cones with different spectral sensitivities. Some subsequent work suggests that when normal color vision individuals who possess trichromat photopigment opsin genotypes are compared to normal color vision individuals with genotypes permitting potential retinal tetrachromacy, then systematic color perception variations across observers may be found. (Mollon (1992) Nature; Jordan and Mollon (1993) Vision Res.; Jameson et al. (2001) Psych. Bulletin & Review; Bosten et al. (2005) Current Biology; Jordan et al. (2010) J. of Vision; Jameson et al. (2016). J. of Imaging Science & Technology). Here we employ a novel kind of method-of-adjustment procedure, under three different adaptation conditions, which requires observers to match surface color stimuli using pigment mixtures in a color reproduction task. Measurements of resulting surface reflectance spectra were analyzed using machine learning approaches, and formally modeled to embed participant’s color reproduction data in perceptual color space, with the aim of (i) determining if systematic color perception variations could be associated with photopigment opsin genotypes, and (ii) further clarifying the potential perceptual impacts of expression of more than one L-cone photopigment variant. Results suggest that the novel empirical and analysis procedures employed bring new insights to the perceptual consequences of possessing more than three types of cones with different spectral sensitivities.