Jim:
It appears that tetrachromacy in the human female comes in two different
flavors, "funky red" and "funky green." You can visualize the rods and
cones for a particular color as a bandpass filter, just as we use the
concept at RF. (Small difference: instead of frequency, optickers think in
terms of wavelength, usually in units of nanometers.) Thus, the normal red
rods and cones are a bandpass filter with a peak at about 636 nanometers.
In a human female tetrachromat with "funky red" vision, the fourth set of
rods and cones are a bandpass filter with a peak shifted 4-7 nm from the
normal red. Similarly, in a female tetrachromat with "funky green" vision,
the fourth set of rods and cones are a bandpass filter with a peak shifted
4-7 nm from the response of the normal green.
Two filters differing by such a small shift in frequency response does not
look like it would have much effect, but the practical effect can be quite
dramatic. For example, the perceptual difference between the tetrochromat
and a person with "normal" vision is that the "funky red" tetrochromat can
consistently distinguish between shades of red-pink-orange that are look
exactly the same to people with normal color vision. (The fact that the
distinction in the spectra of these different shades is real can be tested
with optical spectral analysis instruments such as interferometers.)
One peer-reviewed discussion of tetrachromacy is in the following paper:
Richer color experience in observers with multiple photopigment opsin genes,
Kimberly A. Jameson ;Susan M. Highnote ; Linda M. Wasserman
Psychonomic Bulletin & Review Volume: 8 Number: 2 Page: 244 -- 261
73,
Steve
AA4AK
At 12:58 PM 1/26/2005 -0500, you wrote:
Stephen,
What are the four colors they see?
Thanks,
Jim
W4BQP
Stephen W. Kercel wrote:
It is worth mentioning that the female retina is generally more richly
endowed with rods and cones than the male retina. In fact, a small
percentage of women actually experience four primary colors.
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
