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I suspect there's a spectrum [of color perception among people with nominally normal color vision]. Indeed there is. The most common is a variant carried by ar

by gone35 12y ago

I suspect there's a spectrum [of color perception among people with nominally normal color vision]. Indeed there is. The most common is a variant carried by around 2/3 of the human population (depending on ethnicity and gender), which results in a slightly different red response curve, as shown in color matching tests [1]; and might also be involved in some forms of actual color blindness. Other, less common variations involve mosaicism of both red and green pigments as well [see ibid, Fig. 8]. The tetrachromacy thing is a perennial media favorite these days; but IMO these subtler but actually widespread differences are much more interesting, at least from a philosophy of mind point of view. [1] Deeb 2005 - The molecular basis of variation in human color vision. Link below: http://www.mbfys.ru.nl/staff/j.vangisbergen/endnote/endnotepdfs/colleges/NEUROBIOFYSICA/HC%20colleges/plaatjes%20en%20files/vision/kleurenzien/DEEB_hybride-genen-kleur.pdf http://www.mbfys.ru.nl/staff/j.vangisbergen/endnote/endnotep...

jrapdx3 12y ago
Thanks for the reference, I hadn't seen it previously. In males, the variation appeared to be more toward decreased color perception, except for one variation associated with increased red sensitivity. It does raise the interesting but perhaps unanswerable question of the similarity or difference of the effect of the molecular variation vs. tetrachromacy on color perception. Would greater red sensitivity of L cones in effect produce equivalent visual experience as having a fourth type of cone? Since the visual system computes color on the basis of differential response in M and L cones at time t, having a greater separation of M and L spectra would be sufficient information to compute a larger range of intermediate colors vs. the normal L-M difference. The presence of another node L' between L and M could just be redundant input and not necessarily adding information to the color computation. A question that arises here is if S M L L' females have better color perception is it because of having L and L' or would it reflect L' being more distant from M than the typical single L of female trichromats. That may be significant in light of lack of clear findings of direct benefit to female color perception in those having L L' retinal mosaics. EDIT: Actually, to my way of thinking, the issue is more precisely color discrimination, which is fairly directly measurable vs color perception, a less tractable concept.

by gone35 12y ago

jrapdx3 12y ago

Thanks for the reference, I hadn't seen it previously. In males, the variation appeared to be more toward decreased color perception, except for one variation associated with increased red sensitivity. It does raise the interesting but perhaps unanswerable question of the similarity or difference of the effect of the molecular variation vs. tetrachromacy on color perception. Would greater red sensitivity of L cones in effect produce equivalent visual experience as having a fourth type of cone? Since the visual system computes color on the basis of differential response in M and L cones at time t, having a greater separation of M and L spectra would be sufficient information to compute a larger range of intermediate colors vs. the normal L-M difference. The presence of another node L' between L and M could just be redundant input and not necessarily adding information to the color computation. A question that arises here is if S M L L' females have better color perception is it because of having L and L' or would it reflect L' being more distant from M than the typical single L of female trichromats. That may be significant in light of lack of clear findings of direct benefit to female color perception in those having L L' retinal mosaics. EDIT: Actually, to my way of thinking, the issue is more precisely color discrimination, which is fairly directly measurable vs color perception, a less tractable concept.