Re: NANFA-L-- color vision testing

Mysteryman (
Thu, 15 Dec 2005 23:59:30 -0800 wrote:

>I don't even know how you can tell if one human perceives a color the same as
>another human.

I used to work in a yarn factory. Exact color perception is critically
important in that job, for if one spool of yarn is off-color by even a
tiny bit, an entire section of carpet would be ruined. Therefore a color
vision test is mandatory for all employees, and it's a real toughie.

The test consists of a series of little round color chits which the test
taker must arrange in the correct gradient order. On one end of the test
board is a base starting color, and on the other is another base ending
color. One end, for example, is bright, pure, vivid green. The opposite
end is purple. The 24 color chits are all varying shades of
greenish-purple & purplish-green. They must all be arranged in the
correct order so as to create a perfectly smooth transition between the
two base colors.
Lemme tell ya, it's a tough task.
After that the test taker moves on to the other samples in the series
which use different base colors like orange & blue, tan & cream,
mushroom & taupe, maroon & vermillion, yellow & red, red & green, purple
& green, and so forth; there are a dozen of these series. Some measure
differences in very dissimilar colors, and some measure acuity within a
more narrow spectrum, like blue to purple.

If someone doesn't see the same standard colors as the people who
devised the test, they can't pass it.
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