Advantages and disadvantages of human dichromacy

Sharpe, Lindsay T.; Luca, Emanuela de; Hansen, Thorsten; Jägle, Herbert; Gegenfurtner, Karl R.

doi:10.1167/6.3.3

Cited by 32 publications

(26 citation statements)

References 48 publications

(62 reference statements)

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“…In those experiments, the advantage was observed when subjects were detecting targets defined by luminance and were breaking color-camouflage (Morgan et al, 1992;, and it was explained by the greater capacity of protanopes to use luminance cues (Sharpe et al, 2006). However, the task and stimuli in those studies were very different from those in our present experiments.…”

Section: Advantages Of Dichromacy and Disadvantages Of Trichromacycontrasting

confidence: 62%

“…There are reports showing advantages of dichromacy over trichromacy for some behaviors (Morgan, Adam, & Mollon, 1992;Sharpe, de Luca, Hansen, Jagle, & Gegenfurtner, 2006). In those experiments, the advantage was observed when subjects were detecting targets defined by luminance and were breaking color-camouflage (Morgan et al, 1992;, and it was explained by the greater capacity of protanopes to use luminance cues (Sharpe et al, 2006).…”

Section: Advantages Of Dichromacy and Disadvantages Of Trichromacymentioning

confidence: 98%

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Color vision test for dichromatic and trichromatic macaque monkeys

et al. 2013

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Dichromacy is a color vision defect in which one of the three cone photoreceptors is absent. Individuals with dichromacy are called dichromats (or sometimes "color-blind"), and their color discrimination performance has contributed significantly to our understanding of color vision. Macaque monkeys, which normally have trichromatic color vision that is nearly identical to humans, have been used extensively in neurophysiological studies of color vision. In the present study we employed two tests, a pseudoisochromatic color discrimination test and a monochromatic light detection test, to compare the color vision of genetically identified dichromatic macaques (Macaca fascicularis) with that of normal trichromatic macaques. In the color discrimination test, dichromats could not discriminate colors along the protanopic confusion line, though trichromats could. In the light detection test, the relative thresholds for longer wavelength light were higher in the dichromats than the trichromats, indicating dichromats to be less sensitive to longer wavelength light. Because the dichromatic macaque is very rare, the present study provides valuable new information on the color vision behavior of dichromatic macaques, which may be a useful animal model of human dichromacy. The behavioral tests used in the present study have been previously used to characterize the color behaviors of trichromatic as well as dichromatic new world monkeys. The present results show that comparative studies of color vision employing similar tests may be feasible to examine the difference in color behaviors between trichromatic and dichromatic individuals, although the genetic mechanisms of trichromacy/dichromacy is quite different between new world monkeys and macaques.

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Section: Advantages Of Dichromacy and Disadvantages Of Trichromacycontrasting

confidence: 62%

Section: Advantages Of Dichromacy and Disadvantages Of Trichromacymentioning

confidence: 98%

Color vision test for dichromatic and trichromatic macaque monkeys

et al. 2013

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“…In principle, " 2 could have little or nothing to do with relative L-and M-cone numbers but instead reflect the relative L-and M-cone contrast gains. This view is doubtful, however, given that L:M-cone ratio estimates derived from luminous efficiency functions correlate with estimates derived in the same subjects using other methods (e.g., Albrecht, Jägle, Hood, & Sharpe, 2002;Brainard et al, 2000;Kremers et al, 2000;Lutze et al, 1990;Rushton & Baker, 1964;Sharpe, de Luca, Hansen, Jägle, & Gegenfurtner, 2006;Vimal et al, 1989;Wesner, Pokorny, Shevell, & Smith, 1991). Nevertheless, any claims that luminous efficiency can be used to derive cone numerosity directly should be treated with extreme caution.…”

Section: Luminous Efficiency and Relative L-and M-cone Numerositymentioning

confidence: 99%

The dependence of luminous efficiency on chromatic adaptation

et al. 2008

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We investigated the dependence of luminous efficiency on background chromaticity by measuring 25-Hz heterochromatic flicker photometry (HFP) matches in six genotyped male observers on 21 different 1000-photopic-troland adapting fields: 14 spectral ones ranging from 430 to 670 nm and 7 bichromatic mixtures of 478 and 577 nm that varied in luminance ratio. Each function was analyzed in terms of the best-fitting linear combination of the long- (L) and middle- (M) wavelength sensitive cone fundamentals of A. Stockman and L. T. Sharpe (2000). Taking into account the adapting effects of both the backgrounds and the targets, we found that luminous efficiency between 603 and 535 nm could be predicted by a simple model in which the relative L- and M-cone weights are inversely proportional to the mean cone excitations produced in each cone type multiplied by a single factor, which was roughly independent of background wavelength (and may reflect relative L:M cone numerosity). On backgrounds shorter than 535 nm and longer than 603 nm, the M-cone contribution to luminous efficiency falls short of the proportionality prediction but most likely for different reasons in the two spectral regions.

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“…Acquired color vision deficiencies will not be considered here [14,15]. Although there may be some advantages of color vision deficiencies [16,17], an immediate effect is the reduction in chromatic discrimination, hence a reduction in the number of perceived colors. However, how much this impairment affects the number of colors perceived is still an open question.…”

Section: Introductionmentioning

confidence: 99%

Number of discernible colors for color-deficient observers estimated from the MacAdam limits

et al. 2010

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We estimated the number of colors perceived by color normal and color-deficient observers when looking at the theoretic limits of object-color stimuli. These limits, the optimal color stimuli, were computed for a color normal observer and CIE standard illuminant D65, and the resultant colors were expressed in the CIELAB and DIN99d color spaces. The corresponding color volumes for abnormal color vision were computed using models simulating for normal trichromatic observers the appearance for dichromats and anomalous trichomats. The number of colors perceived in each case was then computed from the color volumes enclosed by the optimal colors also known as MacAdam limits. It was estimated that dichromats perceive less than 1% of the colors perceived by normal trichromats and that anomalous trichromats perceive 50%-60% for anomalies in the medium-wavelength-sensitive and 60%-70% for anomalies in the long-wavelength-sensitive cones. Complementary estimates obtained similarly for the spectral locus of monochromatic stimuli suggest less impairment for color-deficient observers, a fact that is explained by the two-dimensional nature of the locus.

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Advantages and disadvantages of human dichromacy

Cited by 32 publications

References 48 publications

Color vision test for dichromatic and trichromatic macaque monkeys

Color vision test for dichromatic and trichromatic macaque monkeys

The dependence of luminous efficiency on chromatic adaptation

Number of discernible colors for color-deficient observers estimated from the MacAdam limits

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