[Elecraft] Interpreting Color Codes

[Stephen W. Kercel]

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.