Jim Green says (about my wife calling cyan "blue"): You have demonstrated
that your wife sees the same wavelengths as you do but not that she has the
same visual experience that you do. She sees what you call cyan as bluish
and you see it as greenish.
John Denker says: If I wanted to ask somebody to hand me that shirt, I
would ask for the blue shirt. I would fell silly calling it a cyan shirt.
I agree with John. I disagree with Jim. I do not see "cyan" as greenish.
I only realize this is the case (intellectually) because I have measured it.
Indeed at one time I also called objects blue that actually have a fair
amount of green in them. It was only when I began measuring the light
emitted/reflected by objects that I realized a "true blue object" (having
essentially zero light emission/reflection above roughly 490 nm wavelength)
looks very dark blue, whereas objects with a fair amount of green
(approaching cyan) are what al lot of people (including me) might call "sky
blue" (in Ohio, anyway... perhaps not CO, AZ, or NM).
This is not because we perceive it differently, it's just because we learned
to give it this name or that name. My dad and I do not perceive a
replaceable lead pencil differently, but he calls it an "Eversharp" and I
call it a "mechanical pencil." We learned to call the same thing by
different names.
In a paper I published several years ago (Phys. Teach., March 1986) about
measuring refractive indices, I said I have students look at the spectrum of
an incandescent light with a prism on a spectrometer, and I have them find
the wavelengths of light that they think describe... the IR-red boundary,
the red-green boundary (yellow), the green-blue boundary (cyan), the blue-UV
boundary. I also stated that students agree very well that these
wavelengths are approximately 720, 590, 510, 410. The brightness of the
light makes some difference at the ends (720 and 410), but for sure, the 590
and 510 numbers are easy to agree on for students with "normal" vision. I
have gotten wide agreement on this for years with many students.
However, back home, if I show my wife the color she calls blue really has a
lot of green in it, she actually understand even though she is not a
scientist. But she still calls it blue for the following reasons: (1) she
can call it whatever color she wants. (2) She is not alone in this regard
and she knows it. (3) She likes to irritate me by showing me that just
because science proves me right she doesn't have to put up with it... "I
don't care how the experiment comes out, this is my favorite color and I
choose to call it blue."
If I am in the situation John Denker described, I might say "grab that cyan
shirt for me" if I feel like engaging in a discussion about color. I
frequently do that with my wife. But if I really want the shirt in a hurry
I say, "grab that blue shirt for me." Sometimes we have to give in, even
though we know better, just to get the job done.
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817