Not all perception people dismiss the importance of Land's work.
See, for example,
http://www.purveslab.net/
One issue to consider is that the visual system must take into
account the relationship of the spectral distribution of the
illuminance (the distribution of the wavelengths striking the
object) and the distribution of the wavelengths bouncing off the
object (the spectral luminance). What makes something "white" is
that it reflects the illuminance of the scene in equal
proportions not that the luminance from the scene is equal. In
other words, White does not equal amounts of R+G+B, instead
Whiteness = the lack of deviation from the baseline spectral
illuminance. (Hence, the difficulty in training beginning
photographers to understand the different effects of a light
source like daylight vs. tungsten light.) So if other portions of
the scene change their wavelength-mixes then the estimate of the
baseline illuminance will change and the color judgment of a
particular wavelength-mix from an object will change.
The Purves lab site provides some clear examples of this process.
Ken
Christopher D. Green wrote:
Years ago (about 1986) I saw a great film on color perception from the
perspective of the (controversial) retinex theory of Edwin Land. It had
a truly stunning scene in which one is shown one of Land's "Mondrian"
displays, and attention is drawn to a green square within it. Then a
mask is dropped into the projector so that all but this one square is
blocked from view, and we see that in isolation it appears pink, and
that the original apparent green color was created by the influence of
the colors surrounding it. Whatever one thinks of retinex (and most
perceptionists despise it), it is a fabulous demonstration of the
maleability of color perception in the "real" world (as opposed to in
splendid Helmholtzian laboratory isolation) and can generate a good
class discussion of how the phenomenon came to be. Unfortunately, I do
not recall the name of hte film and have never seen it again. Does
anyone else know?
Regards,
Chris
--
Christopher D. Green
Department of Psychology
York University
Toronto, ON M3J 1P3
Canada
416-736-2100 ex. 66164
[EMAIL PROTECTED]
http://www.yorku.ca/christo/
==================================
Gerald Peterson wrote:
Tipsters: I am planning on re-vamping my Intro psych material on color. I
always like to challenge students to think more carefully about what is taken
for granted in their perceptual experience. Color perception presents a door
for some interesting discussion--namely, where is color? Many psych texts like
to point out that color perception is the perceptual product of the brain's
handling of reflected wavelengths and that color is not in the object. I
don't think this view is entirely adequate, as it implies that the intrinsic
features of the viewed object is without color or not importantly (and
adaptively) tied to the perception. I am not aware of an adequately integrated
and accepted theory in this area. I am not a Sensation and Perception
specialist but enjoy getting students to think about these issues. I would
like to point to an on-line source for explanation, answers to this question,
or further discussion of this topic and would appreciate a
ny help tipsters may provide. I also use this class discussion to further examine the principle of parsimony. Thanks, Gary Peterson
Gerald L. (Gary) Peterson, Ph.D.
Professor, Psychology
Saginaw Valley State University
University Center, MI 48710
989-964-4491
[EMAIL PROTECTED]
---------------------------------------------------------------
Kenneth M. Steele, Ph.D. [EMAIL PROTECTED]
Professor
Department of Psychology http://www.psych.appstate.edu
Appalachian State University
Boone, NC 28608
USA
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