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From: dorettas@iddic.UUCP (Doretta Schrock)
Newsgroups: net.sci
Subject: Re: ...what brain tells us about behavior (a little long)
Message-ID: <2209@iddic.UUCP>
Date: Mon, 30-Sep-85 16:20:41 EDT
Article-I.D.: iddic.2209
Posted: Mon Sep 30 16:20:41 1985
Date-Received: Thu, 3-Oct-85 04:49:13 EDT
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> >At 8 weeks a child is 
> >still neurologically immature, in terms of cerebral development, so their 
> >affective behavior is fairly limited.
> 
> It's not clear to me what is being said here.  Is someone proposing that the
> reason that young children are said to have limited affective behavior is
> because they lack what we call cerebral development?

I don't think that was my main point, though I guess my answer to your question
would be a partial "yes."  Children from pre-birth to about age 6 or 8 are in
the process of cerebral development.  The amount of activity falls off pretty
sharply after the first 18 to 24 months of infancy, however.  During this
time, there is a lot of developmental activity going on, primarily cortical 
cell growth, division, migration, myelination, and death (some areas of the 
brain lose up to 85% of their initial complement of neurons during early 
childhood (Cowan, Sci Am 1979)).  Barring somewhat extreme dualist/spiritualist
views, this state of dynamic growth (both in terms of numbers of neurons and
in numbers of synapses) must both affect and be affected by the child's type
and range of behavior.  There is much psychological research that has been done
(on animals) that show the cortical effects of differences in early 
environments, up to and including extreme visual impairment in the case of 
kittens who wore special glasses and whose brains did not develop the ability 
to distinguish vertical (or horizontal, depending upon the group) lines in the
environment.  Thus, an infant's brain is capable of a rather limited range
of actions and responses that gradually widens as the child gains experience
and develops neurally.

> What prevents us, having observed "limited affective behavior", and having
> established that it's specific to infants, from saying that we observe
> various sorts of limited development in infants, including the the sort we
> call "neurological"?  What is added to this account by saying that what
> explains the limited affective behavior is the neurologically immaturity?
> -- 
> 					-- Jon Krueger

If I understand your question (and I'm not sure that I do), it would seem
to have been answered above.  In addition, what would you propose as an
explanation of the rate and type of changes in infant behavior if not 
the development of the brain (primarily the cerebral cortex) and
nervous system?  Most of the other bodily systems (with the exception of
the reproductive system -- but most of us don't use that for determining
our behavior :-) are nearly fully developed at birth.  Nor can lack of
experience be the sole or main determinant, as otherwise the Skinnerian 
behaviorist models of language aquisition, etc., would have held up to 
observation and experimentation better than they have.  It is clear that
there are *both* developmental (as an expression of genetics) and 
environmental (i.e., experiential) components to the way a child's range,
type, and depth of behavior changes.  Attributing the locus of change
primarily to the nervous system would seem to simply be the most 
parsimonious theory that fits all the facts.

You might want to read the articles I suggested in my last posting,
or most anything by Pylyshyn.  A lot of William Cowan's work also focuses
on this sort of thing.

		-- Mike Sellers (note the name difference from above)


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