Date: Mon, 20 Jul 1998
Metaphysics of Consciousness
Thomas M. Miovas, Jr.
>From: Jason Crawford
>"Opponent processing" is a theory of color vision which
>basically says that in any scene, your eye latches onto
>something which it considers to be white, and then
>processes all other colors relative to that standard.
>So, if you are out skiing, and are wearing yellow-tinted
>goggles, the world will be yellow-tinted when you first
>put them on. But after a minute or two of looking at the
>bright white snow, the world will seem to be normally colored
>again. When you take the goggles off later, things
>will be tipped the other way: everything will be slightly
>blue-tinted. Again, after a minute or two, your color vision
>will be back to normal.
I'm not sure normal color vision always returns after a few
minutes. I used to work for a factory that made titanium dioxide
powder, which was billed as "the word's whitest white" -- and it
was. After working in the packing area (tossing around 50 lb
bags of the stuff) for a short time (a week or so), everyone
began to notice that white paper napkins began to look very
beige, and they looked that dingy beige color during the entire
lunch period. Given this, I'd say memory is involved somehow in
the processing of (at least) the visual receptors. That is,
there seems to be a continuous "re-tooling" of the "visual
context." If one is continuously exposed to a brilliant white,
the entire mechanism of perception seems to shift, making the
formerly white-looking things in one's surroundings take on a
dingier color -- even when one is no longer exposed to the more
brilliant white.
This is true also for "white noise" -- a continuous noise in the
background -- that after enough exposure, isn't noticed at all,
though it does seem to make one more receptive to other noises
one wouldn't have otherwise heard.
It's as if the "perceptual context" is always adjusted to
accommodate one's surroundings -- and the shift takes quite some
time to "roll back" to the previous settings, if one is going to
be exposed to the unusual setting on a continuous bases. That
is, I wonder if the ski patrol, who might be wearing tinted
goggles more often than most people throughout the winter,
adjust to seeing things "discolored" for a longer period of time
compared to those who only put the tinted goggles on occasionally?
At any rate, one doesn't even need to have both eyes covered
with a tinted material. I once lost one lens in my sunglasses
while climbing a snowy mountain trail. For several minutes, my
eyes were "out of sync" -- I couldn't tell if everything was
tinted or everything was white. Then they adjusted, and
everything looked the same -- through either eye! The glare from
the uncovered eye even seemed to be lessened to a large degree,
as if my visual reception mechanism could block the glare
without sunglasses. If I took off the sunglasses, the glare was
overwhelming, even after a few minutes. The difference between
the two eyes was able to balance somewhere between fully tinted
and fully glaring, with only one tinted glass.
