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pudge (1)

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Journal of pudge (1)

Saturday September 04, 2004
06:00 PM

Color Blind

[ #20732 ]

I was diagnosed with color blindness as a child. I was told I was red-green color blind. However, this never made much sense to me, because I can tell the difference between red and green ... or can I?

OK, yes, I can. But reds seem duller to me. I have what is sometimes called "red weakness." There are three basic photopigments (colors) we humans see: red, green, and blue. People with normal sight are trichromats, whereas people we normally think of as color blind are monochromats: they see no pigment at all, or only one color (usually blue, the shortest wavelength).

Then there's dichromats, who cannot see one of the three wavelengths. I'm a trichromat like most people, but an anomalous one. Specifically, I am protoanomalous trichromat, which means my red photoreceptors are abnormal.

This explains some of why my wife says I can't tell the difference between various colors, but she thought it was all in my mind, because I can tell the difference between red and green, despite my story about what the doctor told me when I was a kid. I showed her two pictures, showing what a normal person sees, and what someone like me sees. My problem isn't very acute, and I can see the number "2" in the normal picture, but I have to strain for it. I can see some difference between the two pictures, but it is very slight. My wife sees a significant difference between the two.

(BTW, I got these pictures from a web site that created them using a color filter from wickline.)

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  • Next time I need a name for an RPG, its going to be Protoanomalous Trichromat.
  • Some birds have four pigments, and see more colors than we trichromats can. (The extra pigment helps them see colors in the UV edge of the visual spectrum -- useful for identifying flowers.)

    If they designed those test-your-color-vision pictures instead of mere humans, we'd all fail their tetrachromat tests. They'd laugh at us. Little chirpy laughs. Full of pity and condescension at our inability to look at a flower and see the "FREE POLLEN HERE" sign in ultrapurple.

    • I remember having read an article somewhere about tetrachromats detected in the human population. Without linguistic support, they were unable to think about the extra colours they were seeing. As a dichromat, I find the interaction between languages and colour perception fascinating.
      • I remember reading something about that a year or so ago.

        IIRC, tetrachromatism in humans is almost exclusively a female trait, much like all forms of color blindness is almost exclusively a male trait. The difference between avian tetrachromatism and human tetrachromatism is that people with the trait do not have ultraviolet color receptors, but have two sets of green (?) color receptors, so they can more finely distinguish colors in the middle of the human-visible spectrum. (I think one test was to tel

        • We probably read the same blogs :)

          I wonder what evolutionary advantages tetrachromatism would bring to humans. It is a very probable hypothese that perception of colours becomes more accurate through centuries (studying the vocabulary colours in ancient indo-european languages confirms this.)

  • Do not let me pick out your clothes. You WILL regret it. :-)