What do colour-blind people see?

Viénot, Françoise; Brettel, Hans; Ott, Laurent; Mbarek, Atika; Mollon, J. D.

doi:10.1038/376127a0

Cited by 119 publications

(98 citation statements)

References 9 publications

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“…Research on dichromacy has covered various topics such as genetics (2), psychophysics (5), color naming (11,15), and even color-appearance models (7,16,25). Here we provide a novel report of the color preference of red-green dichromats and compare their color preference with the color preference and its explicative mechanisms of normal trichromats, including suitable transformations of such mechanisms for dichromats (L* T and s′).…”

Section: Discussionmentioning

confidence: 99%

Color preference in red–green dichromats

Álvaro

Moreira

Lillo

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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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...

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Section: Discussionmentioning

confidence: 99%

Color preference in red–green dichromats

Álvaro

Moreira

Lillo

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…It is now possible to transform colour images to represent their colour appearance for dichromats: the digital technology is available and the physiological mechanisms of normal and abnormal colour vision are well enough known for transformation algorithms to be constructed. 42,43 Transformation programs are freely available on the internet so any digitised colour image can be transformed. 44,45 Transformation of colour images to dichromatic appearance can provide the clinician with a fuller appreciation of the coloured world of those with abnormal colour vision.…”

Section: The Difficulties Of Giving Advicementioning

confidence: 99%

Assessment of inherited colour vision defects in clinical practice

Cole

2007

Clinical and Experimental Optometry

121

127

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Background: Colour vision deficiency (CVD) has a high prevalence and is often a handicap in everyday life. Those who have CVD will be better able to adapt and make more informed career choices, if they know about their deficiency. The fact that from 20 to 30 per cent of adults with abnormal colour vision do not know they have CVD suggests that colour vision is not tested as often as it should be. This may be because of practitioner uncertainty about which tests to use, how to interpret them and the advice that should be given to patients on the basis of the results. The purpose of this paper is to recommend tests for primary care assessment of colour vision and provide guidance on the advice that can be given to patients with CVD. Methods: The literature on colour vision tests and the relationship between the results of the tests and performance at practical colour tasks was reviewed. Results: The colour vision tests that are most suitable for primary care clinical practice are the Ishihara test, the Richmond HRR 4th edition 2002 test, the Medmont C‐100 test and the Farnsworth D15 test. These tests are quick to administer, give clear results and are easy to interpret. Tables are provided summarising how these tests should be interpreted, the advice that can be given to CVD patients on basis of the test results, and the occupations in which CVD is a handicap. Conclusion: Optometrists should test the colour vision of all new patients with the Ishihara and Richmond HRR (2002) tests. Those shown to have CVD should be assessed with the Medmont C‐100 test and the Farnsworth D15 test and given appropriate advice based on the test results.

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“…Although the authors were aware that the quality of the sensations of other people cannot be fully known (page 128 in Ref. [15]), they described the rationale of an algorithm designed to simulate the chromatic appearance for a dichromat, in order to allow a normal trichromat to experience the same colors as a type of dichromat when looking at the same scene. The algorithm used to obtain this kind of simulations is described in more detail in Ref.…”

Section: Color Appearance: What Are the Colors Seen By Dichromats?mentioning

confidence: 99%

Colorimetry and Dichromatic Vision

Moreira¹,

Álvaro²,

Melnikova³

et al. 2018

Colorimetry and Image Processing

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Normal trichromats have three types of cone photoreceptors: L, M, and S cones (most sensitive to long, medium, or short wavelengths, respectively). Therefore, standard colorimetry is based on three variables (X, Y, Z). Dichromats only have two types of functional cones due to genetic factors. The main consequences are that dichromats (1) confuse colors that can only be discriminated by the response of the type of cone they lack and (2) make errors when naming colors. Chromaticity diagrams can be used to specify dichromats' color confusions. Confusion points represent imaginary stimuli that only activate L, M, or S cones. Confusion lines radiate from confusion points and represent pseudoisochromatic stimuli (i.e., colors confused by the corresponding type of dichromat if presented at an appropriate intensity). Dichromat's color appearance models have been developed to simulate the colors supposedly seen by dichromats, and there exist color simulation tools that implement some of those models.

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What do colour-blind people see?

Cited by 119 publications

References 9 publications

Color preference in red–green dichromats

Color preference in red–green dichromats

Assessment of inherited colour vision defects in clinical practice

Colorimetry and Dichromatic Vision

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