Re: orange flies

In article <3s5p625d3ddkc9rrc3pdedfod686davet4@xxxxxxx>,
rdean3REMOVE@xxxxxxxxx writes:
On Thu, 18 May 2006 08:54:26 -0600, rw <rw56_to_the_chase@xxxxxxxxxxxxx>
wrote:

rdean3REMOVE@xxxxxxxxx wrote:

How would the trout's optic "wiring" change the way the light is
reflected from an object? As I said in the other post, I can understand
that trout might perceive, for example, what humans call "orange" as
what humans call "purple," but I can't see how trout would arbitrarily
and randomly perceive one color differently. IOW, the trout's
perception of this or that color might be different than a human's, but
it would be consistent. But again, ???

The point is that fish are sensitive to a different spectrum than we
are. They see "colors" we simply don't see. If the object is to match
the color of the pattern to the color of the natural, AS SEEN BY THE
FISH, we cannot reliably make that judgment with our eyes, because we
aren't sensitive to the same colors as the fish are.

It's analogous to a color blind person trying to paint a picture that
will look natural to a normally sighted person. It can't be done. Or at
least it can't be done without the painter resorting to objective
technical methods that don't rely on his subjective perception (matching
pigment to measurements of light from the scene, for example).

I don't see how a optic perception "defect" (color-blindness) would come
into play - a color-blind human will see (really, perceive) the same
color the same way all the time. If a color-blind person were to paint


Actually, not true. In my case, the color I see can be dependent on
both the brightness and the type of lighting source.


a wall with a paint whose color _they_ couldn't see "normally" (let's
use orange) and 50 people of "normal" color vision were asked the color
of the wall, they'd say "orange." The fact that the painter was
color-blind wouldn't effect the "normal" perception. So it seems that
if ("normal") trout perceive orange as what a human would call purple,
if you asked 50 ("normal") trout what color the wall was, they'd all say
"purple." The fact that humans and trout see it differently isn't
material because the difference is constant. And to take it further,
let's say color-blind trout saw orange as what humans call "green," it
would seem that trout would answer "green" as to the wall, a cabinet, or
anything else painted with the orange (to humans) paint, so even if one
were in an area of color-blind fish, the difference would still be
constant.



Rubbish. Things are much more complicated. The situation is that the
color and brightness perceived is a convolution of the spectral response
of the eye in question and the spectrum of the light reflected off the
object in question. Give me a green wire with a red stripe, the wire may
look like a solid color using an incadenscent light source and the same
wire may appear to be striped under a florescent light source. The
difference is that the spectrum of the light reflected off the wire has
changed due to the change in the spectrum of the light source. On the
flip side, I have some suspicions that I can see subtle differences in
samples of the same color better than people with "normal" color vision,
although I may not be able to tell you what the color is. The issue is
that we don't speak the same color language and there is no color lookup
table with a one to one correspondence.

In the case of fish and orange, there is no guarantee that if you tie two
versions of the same orange pattern, using say a dyed feather and an
artificial material, that look identical to you, will look identical to
a fish as the spectral properties of the two materials will be different.

I think that the bottom line is that fish, at least trout, are mostly
bug eating machines. Some times they are keyed on forms that are
plentiful due to activity related to a hatch. At that time, they may
be keying to a size, shape, and a tint or hue that may be very hard
to match. Other times, they might be looking for targets of opportunity.
In this case, the bright colors we like to use may contrast enough with
the stuff floating by that the fish is motivated to check it out.



TC,
R

________________________________________________________________________
Craig A. Gullixson
Instrument Engineer INTERNET: cgullixson@xxxxxxx
National Solar Observatory/Sac. Peak PHONE: (505) 434-7065
Sunspot, NM 88349 USA FAX: (505) 434-7029
.