On 10 Nov 2009 at 17:20, [email protected] wrote:
>
> A question arose today about when babies can perceive color. Is it an innate
> ability? The
> opposing view is that they can only see black and white at birth and color
> requires neurological
> development and maturation.
Colour discrimination demonstrations in the very young goes
back many years but all of the earliest literature is suspect
because of failure to control for differences in brightness.
Without this control, it's possible that a baby is discriminating,
not on the basis of wavelength, but on the basis of difference in
perceived brightness. Correcting using psychophysical data for
the adult is no solution, because the baby's psychophysical
response may be different.
The problem was solved by complicated studies which
systematically varied the test stimuli through all values of
brightness. The experimenters would not know when the baby
saw them match on brightness, but performance would fall to
chance at that point. If two different hues are tested, and at no
point does the baby's performance fall to chance, then the
discrimination cannot be due to brightness. The baby must be
discriminating on the basis of colour. Brilliant (pun intended)!
The research indicates that the black-white only claim is wrong,
as a newborn does have some colour vision. But the newborn
may be only a dichromat, having a deficiency in perceiving blue.
However, colour vision performance rapidly improves.
One study demonstrating such things is this:
Vision Res. 1994 Jul;34(13):1691-701.
Systematic measurement of human neonatal color vision.
Adams RJ, Courage ML, Mercer ME.
although there probably are more recent ones as well.
The paper which first found a way to solve the brightness
conundrum was, I think, this one (although in 2-month olds, not
neonates).
Color vision and brightness discrimination in two-month-old
human infants DR Peeples and DY Teller
Science 26 September 1975 189: 1102-1103
Abstract. A red or white bar, embedded in a white screen, was
systematically varied in intensity. Infants consistently located
and stared at the white bar unless it closely matched the screen
in intensitY. TheY also stared at all intensities ofthe red bar,
presumptively including the red-white brightness match, and
hence must have some form of color vision
Retrieving this article was difficult because _Science_ and
therefore PubMed have misindexed the author as "Peeles".
Other methodological solutions to the brightness problem came
later.
Stephen
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Stephen L. Black, Ph.D.
Professor of Psychology, Emeritus
Bishop's University
e-mail: [email protected]
2600 College St.
Sherbrooke QC J1M 1Z7
Canada
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