Theiling Online    Sitemap    Conlang Mailing List HQ   

Alien colour spaces and stuff

From:Javier BF <uaxuctum@...>
Date:Saturday, March 6, 2004, 9:20
>> Are their eyes tetrachromatic like those of most birds, too? > >They're closely related to Zireen, and have pretty much the same range >of color vision. They can't see red, but they see into the ultraviolet >range; their primary colors are yellow, turquoise, indigo, and >ultraviolet. "Green" is a secondary color produced by combining yellow >and turquoise.
I assume that by primary and secondary colors you refer to the composition of retinal stimuli. But what are their basic, unmixed colour percepts? I mean, in humans "yellow" is experienced as a completely basic, pure, unmixed colour percept, even though it is produced by stimulating both the S and M cones, that is, even though it is the result of a secondary retinal stimulus. The same goes for "white", which is the epitome of purity even though it is produced by a tertiary retinal stimulus combining S, M and L cones. Let alone black, which is the colour percept caused by the lack of retinal stimulus. The so-called "three primary colours" (red, green and blue) only serve to describe the _stimulus_ space, by referring to the colour sensations produced by a monochromatic light at the sensory peak of each retinal cone. But that's a very different thing from the actual human _perceptual_ chromatic space, which consists of 6 basic pure percepts organized into three axes: one scalar luminosity axis (black-to-white) and two bipolar hue axes (blue-or-yellow, red-or-green). From the data you've just provided, I would infere that Sangari and Zireen vision consists of 8 basic pure colour percepts organized into 4 axes: black-to-white, green-or-violet, yellow-or-turquoise, indigo-or-ultraviolet. I would guess that the green/violet was the first colour distinction to have appeared in the evolution of their chromatic vision, by splitting the original light/no-light photorreceptors into low-freq (green) and high-freq (violet) specialized ones, with white and black becoming "phantom" percepts produced by the combination of data from both. Then the low-freq photorreceptors would have split into lower (yellow) and higher (turquoise) low-freqs, appearing the second hue axis, with green becoming another phantom percept. And finally the high-freq photorreceptors would have similarly split into lower (indigo) and higher (ultraviolet) high-freqs, emerging the third hue axis and violet becoming another phantom percept. Graphically: * Sangari/Zireen monochromatic stage: white | o | black * Sangari/Zireen dichromatic stage: white | . . . green o-----o violet . . . <- spectrum | black * Sangari/Zireen trichromatic stage: (indigo/ultraviolet colour-blinds) white | . . .| . . . | . x turquoise | . . o | . . | | . x green-|--------o violet x . | | . . o | . <- spectrum x yellow | . | | black * Sangari/Zireen tetrachromatic stage: white | | . . . . .|. . . . . | . x turquoise | indigo x . o | o . . | | | . x green-|------------|-violet x . | | | . . o | o . x yellow | ultraviolet x . | . <- spectrum | | black It would be a visual evolution similar to our own: the basic light/no-light (white/black) distinction; then the first splitting of high-freq vs. non-high-freq and the emergenge of the first hue axis (blue/yellow), with white/black becoming phantom percepts; then the second splitting of non-high-freq into low-freq and mid-freq and the emergence of the second hue axis (red/green), yellow becoming a phantom percept: * human monochromatic stage: (achromat people) white | o | black * human dichromatic stage: (red/green colour-blind people) white | | . . . yellow o-----o blue . . . <- spectrum | | black * human trichromatic stage: (normal human vision) white | . . | . . | . x green | . . o | . . | | . x yellow-|--------o blue x . | | . . o | . <- spectrum x red | . | | black A further step in human colour vision seems to have already taken place in the retinas of a few lucky tetrachromat women, where either the red or green photorreceptors are split, emerging a new hue axis. Their colour space thus is supposed to consist of a hue _sphere_ (instead of a hue circle) plus the luminosity axis, rendering a 4D colour space. And they should be able to experience not only two novel pure hues and eight novel binary hues, but also eight wondrous ternary hues, and then of course a myriad intermediate and unsaturated colours between them. All in all taking their colour experience into an unknown level of richness, comparable only to the richness of other tetrachromatic colour spaces like the one of the Sangari/Zireen. * human tetrachromatic stage: (mutant women with split red photorreceptor) white | . . . . | . . . | . x green | . . o | . . | | . x yellow--|----------------o blue x . | | . . o-----o | . . orange | pink | . <- spectrum x red | . | x . x . | | | black Of course, labels like "turquoise" and "violet" for the Sangari/Zireen basic colours in the above schemes (as well as "orange" and "pink" for the extra percepts of mutant tetrachromat women) are misleading, since for us humans "turquoise" doesn't refer to a basic colour percept at all, but to one of our four binary hues (orange, yellowgreen, turquoise and purple)(*), a chromatic perception consisting of green and blue percepts experienced simultaneously. While the "turquoise" of the Sangari/Zireen would be supposed to be experienced as a pure, basic, unmixed percept, independent of the human colour percepts of green and blue, and thus with little to do with what we humans think of as turquoise. So, only the Tirelat (and related conlangs) names for the basic colour percepts of the Sangari/Zireen visual system would be appropriate to describe and talk about their colour experience, we humans being literally unable to truly understand what those words refer to since we lack the appropriate experiential frame of reference, just like a deaf person cannot understand what words like "sound" or "music" actually mean. Cheers, Javier (*) Well, it seems that under laboratory-created visual conditions, certain individuals have been able to enjoy two other binary hues (redgreen and blueyellow), the pairs of opposed percepts merging into such novel binary hues by means of the cortical activity involved in a certain visual illusion, which appears not to be restricted by the usual opposing-process mechanisms of retinocortical visual activity. It could be fun that a conlang had specific names for those two novel hues.


Herman Miller <hmiller@...>
Herman Miller <hmiller@...>