Alien colour spaces and stuff
| From: | Javier BF <uaxuctum@...> |
|---|
| Date: | Saturday, March 6, 2004, 9:20 |
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>> 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.
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