Color representations of normals and congenital red–green color deficiencies based on differential scaling of color-names and color-naming experiments

Abstract

Our previous work revealed that the vision-based color representation of congenitally color-deficient observers (CDOs) was mostly C-shaped bending at yellow and blue that differed from circular shape of the observers with no color vision deficiencies called CNOs in the study. In this study, the color-name-based internal color representation was investigated for the same observers and its relation to the vision-based color representation was examined. First, psychological difference of all combinations of 10 color names corresponding to the Munsell basic hues was rated using a 5-point scale. The distances of all pairs of CNOs and the CDOs agreed well with each other, in contrast to the distinctive differences in the vision-based color representation. Second, color-naming was conducted to the 10 color chips for each of high and medium chroma to link the vision-based and color-name-based representations through the test stimuli. For the high chroma chips, color naming property of the CDOs was similar to that of the CNOs. In contrast, CDOs showed distinctively larger intra- and inter-observer variabilities than CNOs for the medium chroma chips. The difference between two color chips was estimated using the results of the color naming and extended color-name difference ratings which is called “color-naming difference.” No systematic relationship was observed among the color-chip difference, color-name difference, and color naming difference in individual comparisons. It indicated that the color-naming difference is greater for the pairs including YR/Y/GY versus G/B, and vice versa for the pairs consisting of BG, B, PB, P, and RP. These suggest the followings; first, CDOs seem to utilize lightness difference strategically in the visual assessment, second, psychological differences among “blue,” “green,” “purple,” or “gray” are distinct for CDOs although the color chips given those names in our experiment appear close.