Color preference in red–green dichromats

Abstract

Around 2% of males have red-green dichromacy, which is a genetic disorder of color vision where one type of cone photoreceptor is missing. Here we investigate the color preferences of dichromats. We aim (i) to establish whether the systematic and reliable color preferences of normal trichromatic observers (e.g., preference maximum at blue, minimum at yellow-green) are affected by dichromacy and (ii) to test theories of color preference with a dichromatic sample. Dichromat and normal trichromat observers named and rated how much they liked saturated, light, dark, and focal colors twice. Trichromats had the expected pattern of preference. Dichromats had a reliable pattern of preference that was different to trichromats, with a preference maximum rather than minimum at yellow and a much weaker preference for blue than trichromats. Color preference was more affected in observers who lacked the cone type sensitive to long wavelengths (protanopes) than in those who lacked the cone type sensitive to medium wavelengths (deuteranopes). Trichromats' preferences were summarized effectively in terms of cone-contrast between color and background, and yellow-blue cone-contrast could account for dichromats' pattern of preference, with some evidence for residual red-green activity in deuteranopes' preference. Dichromats' color naming also could account for their color preferences, with colors named more accurately and quickly being more preferred. This relationship between color naming and preference also was present for trichromat males but not females. Overall, the findings provide novel evidence on how dichromats experience color, advance the understanding of why humans like some colors more than others, and have implications for general theories of aesthetics.dichromacy | aesthetic preference | color vision | color naming I ndividuals vary in their perceptual experience of the world, and sometimes this variation is caused by genetic differences (1-4). Dichromacy is a form of color-vision deficiency affecting about 2% of human males in which only two of the three types of retinal cone photoreceptors are functional because of genetic factors (1, 2). Protanopes, deuteranopes, and tritanopes lack cone photoreceptors sensitive to long (L), medium (M), and short (S) wavelengths, respectively. Accordingly, dichromats' color discrimination is poorer, and their spectral sensitivity is slightly shifted to longer wavelengths (deuteranopes) or is moderately shifted to shorter wavelengths (protanopes) compared with that of normal trichromats (common observers; see table 3.6 in ref. 5).In normal trichromats, cone responses are the input signals for two chromatic cone opponent mechanisms, red-green and yellowblue, based on L−M and S−(L+M) cone responses, respectively, and one achromatic mechanism, mainly based on L+M responses (1). Traditionally it has been considered that protanopes and deuteranopes lack functionality in the red-green mechanism, because this opponent mechanism is based on the comparison of L and M cone responses, and one...

Colorimetry and Dichromatic Vision

“…For example, the activation of the yellow-blue system was a significant predictor and explained almost two thirds of the variance (R 2 = .61) in protanopes' preference for the full color set and more than three quarters of the preference for saturated (R 2 = .76) and light (R 2 = .88) colors (see Table 1 in Ref. [20]). Besides, this novel study demonstrated that the fluency of processing also underlies males' preference (either normal trichromats or dichromats): there was a higher preference for the colors named more accurately, quicker, more consistently and with greater consensus in normal trichromatic males and dichromatic males but not in normal trichromatic females.…”

“…Model B includes a third variable: the aforementioned residual red-green discrimination. Section 4 deals with an emotional aspect related to color, describing color preferences in red-green dichromats and comparing them to the preferences of normal trichromats [20]. Finally in Section 5, we will summarize the most important conclusions of our research on red-green dichromats.…”

“…For the last case, standard colorimetric measurements have been used to estimate the response magnitudes in the three retinal cones (L, M, and S) and the two opponent mechanisms (red-green, L-M, and yellow-blue, S-(L + M)). Álvaro et al [20] studied color preferences in dichromats and compared them to the preferences of normal trichromats (Figure 6; see also Schloss [38]). …”

“…Color preference of red-green dichromats is different from color preference of normal trichromats [20]. Yellow-blue cone contrast (computed from colorimetric variables) accounts for dichromats' pattern of preference, with some evidence for residual red-green activity in deuteranopes' preference.…”

Perception of color emotions for single colors in red-green defective observers

“…Further study by Álvaro et al (2015) investigated the color preference of red-green dichromats. The results suggested that dichromats have different preferences than that of those with normal color vision; dichromats rated yellow best, unlike normal individuals.…”