On Tue, 30 Oct 2001 22:08:44 +0100, "Urs Enke" <urs.enke at web.de>
wrote:
>For some years now I've wondered
>-- whether the (red-green-blue-mixable) colours we know are all there are in
>this universe, and if not,
>-- whether it might be possible to neurologically change the visual cortex
>(or whatever necessary) to create the sensation of other colours, and
>-- whether there has been any research suggesting that other animals are
>actually seeing different colours than we do.
>>I am neither talking of broadening the EM-spectrum we can see by changing
>the eyes' perception (as this would supposedly simply distribute our known
>"rainbow colors" over that new spectrum), nor of mixing pseudo-new colours
>from the base colours that we already know. Also, I wouldn't consider any
>eye-related limitations essential, as I really mean directly tapping into
>one's brain.
>>I'd be glad to get any feedback, be it on physical possibility, neurological
>practicability or philosophical thoughts. Thanks in advance for brightening
>or dimming my hopes to see "Color X" before I die... ;-)
>>Urs
>>PS: Maybe someone even has information on people reporting previously
>unknown ("unmixable") colours after having been under the influence of
>drugs...?
The question is more philosophical than neurobiological (I am
answering from bionet.neuroscience). There are, indeed, three types
of color receptors in human vision. Presumably all the colors that we
could possibly see would necessarily be the result of stimulating
these in different degrees (aside from the fact that our impression of
color is very sensitive to all sorts of other factors, from the colors
in the vicinity to our recognition of the object that "possesses" the
color to the overall lighting, even to our mood). But the three types
of human color photoreceptors is the basis for the success of three
color mixing in reproducing color.
Other animals, of course, have rather different senses. Many insects
(bee, for example) typically see farther into the ultraviolet but
can't see in the red. So their spectrum is shifted. There is even a
form of "bee violet". In the same way that human violet connects the
two ends of the linear spectrum (red and blue) and turns it into a
circle, bee violet connect the two ends of the bee spectrum. (K. von
Frisch, but I can't find the specific citation just now).
And many physical instruments explore the universe in a different
region of the spectrum producing "false color" images.
But this is spectrum shifting, what you don't want. Unfortunately,
the brain seems to have developed using millions of years of
experience to fine-tune what it perceives. And experience only
produces what our sense organs detect and report to the brain.
If you stimulate the brain artificially, no doubt you will produce all
types of "novel" impressions, never before seen and beyond all our
experience. So how could you ever report a "new color"? What words
could you use? What would you point to to illustrate what you mean?
Even so, I strongly doubt that amidst all the novelty of visual
imaging, there would be any actual new color.