Black is a color percept simple, just like white, blue, yellow, green
and red. It's half of the opponent black-white channel.
This channel (they say, we we don't really know for sure) gets input
from the medium- and long-wavelength cone systems; hence a relative lack
of stimulation of those cones should cause the black-white channel to
signal "black."
But black results from the lack of light reflected from a surface only
relative to the amount of light reflected from other surfaces in the
scene. A good example of this is when you turn off your TV; the screen,
even though all the phosphors are quiet, doesn't appear black (usually
it's a grayish color). But when there are other colors in the scene
(the TV is showing something), the *relative* lack of light emitted from
some phosphors will make some parts of the screen appear black.
I don't know if that helps at all. The main deal is that generally,
yes, "black" results from a uniform absorption of EMR by a surface, but
only relative to other surfaces in the scene. I don't think black is an
aperture color. (But I could be wrong about that last bit.)
m
-------
"Mauchly's Test of Sphericity:
Tests the null hypothesis that the error covariance matrix of the
orthonormalized transformed dependent variables is proportional
to an identity matrix."
---
SPSS
________________________________
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Tuesday, February 06, 2007 7:12 PM
To: Teaching in the Psychological Sciences (TIPS)
Subject: [tips] question about color perception
Sorry for the cross-posting.
After I explained that when we see a color, that color is what
is reflected after the other wavelengths are absorbed by the material,
one of my students asked about the perception of black. She wanted to
know if it is similar to the black pupil in the eye, which is actually a
hole. If it is the absorption of all wavelengths, how is it possible to
have many shades of black? I told her I would seek the expertise of my
colleagues.
Riki Koenigsberg
[EMAIL PROTECTED]
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