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Dear Ping (cc: INFO-CHILDES).,<br>
<br>
<font size=4>I agree with your claim that the "' innate'-versus-'
learned'" dichotomy is a false one -- but maybe not for the reasons
you suggest. You seem to want to abandon the distinction because
you think that experience is always implicated, that "interaction
between experience and brain development" is paramount..
<br>
<br>
You are undoubtedly right that some of the "development of neural
tissues and the like could occur as .. a result of learning
experiences." But how could it be otherwise? Surely
whenever we learn something the brain changes in some way. <br>
<br>
The real question is whether the brain is importantly shaped in ways that
may not have anything to do with learning. The Nelson review that
you mentioned does highlight ways in which experience can play an
important role in shaping the brain, but it leaves out part of the story.
For example, Nelson notes that there are critical periods in the
development of binocular depth perception, but doesn't discuss evidence
that at least some important parts of the visual system are organized
prior to experience. The sorts of visual deprivation studies that Nelson
appears to have in mind (e.g., those of Hubel & Wiesel) have
often been misinterpreted. Though they do show that visual experience
plays a role in development, they do not show that the initial structure
is itself a consequence of learning. Hubel expressed this point clearly
in his 1988 book _Eye, Brain and Vision_ (W. H. Freeman) when he wrote
that<br>
<br>
<blockquote type=cite cite> "the nature-nurture question is
whether postnatal development depends on experience or goes on even after
birth according to a built-in program. We still are not sure of the
answer, but from the relative normality of responses at birth, we can
conclude that the unresponsiveness of cortical cells after deprivation
was mainly due to a deterioration of connections that had been present
birth, not a failure to form because of a lack of experience."
</blockquote><br>
An up-to-the-minute (and cleverly-titled) commentary by Mark Hubener and
Tobias Bonhoeffer ("Eyes wide shut", Nature Neuroscience,
December 1999, volume 2, 1043-1044) goes to making the same point:
"ocular dominance columns and orientation maps can develop almost
normally without visual input". Learning must play some role in
fine-tuning things, but the basic structure seems to be available prior
to (womb-external) experience.<br>
<br>
The empirical evidence is not yet all in, not in the case of language,
and not even in the case of vision, where we have much more
straightforward animal models. But it is clear that biology is full of
mechanisms that can lead to the development of intricately structured
machinery, without requiring learning. <br>
<br>
The reason that we should abandon the "nature-versus-nurture"
dichotomy is not because the distinction is fuzzy, but because the
"versus" gets things wrong. It's not an either-or situation --
there can be no learning without something being innate. And having more
innate machinery typically makes you a better learner, not a weaker one.
Sea slugs can learn, a little. But only a little, because their innate
learning machinery is fairly impoverished. We humans can probably use the
same mechanisms (whatever mechanisms support conditioning have probably
been conserved, evolutionarily speaking), but lucky for us, we seem to
have other innately-given learning mechanisms as well. It's not nature
VERSUS nurture, it's nature AND nurture. Part of development is about
learning, but it part of it is not; we will need to understand both parts
in order to have a complete account. <br>
<br>
Best wishes,<br>
Gary<br>
<br>
<br>
</font>At 01:18 PM 12/1/99 -0500, Ping Li wrote:<br>
<blockquote type=cite cite>Dear INFO-CHILDES Colleagues,<br>
<br>
In light of this list's recent debate on Chomsky's position on
sensorimotor<br>
experience, I'd like to draw your attention to a short article by
Charles<br>
Nelson "Neural Plasticity and Human Development" (Current
Directions in<br>
Psychological Science, Vol. 8, No. 2, 1999, pp.42-45). In this
article,<br>
Nelson reviews many studies that suggest that the development of
neural<br>
tissues and the like could occur at various points in life as a RESULT
of<br>
learning experiences, and that such development could occur at
anatomical,<br>
neurochemical, or metabolic levels (see also a recent article by my<br>
colleague C. Kinsley here on the interaction between motherhood,
neural<br>
growth, and learning and memory; Nature, Vol. 402, 137-138, 1999).
Nelson<br>
goes on to argue that the perennial
"innate"-versus-"learned" debate in<br>
developmental psychology is fallacious. Because the nervous system
changes<br>
in response to the demands of the learning environment, especially early
in<br>
life, it is more important, Nelson suggests, for us to examine the<br>
interaction between experience and brain development (e.g, "the role
of<br>
experience in sculpting neural systems"), than to argue about
whether<br>
aspects of behavior are innate or learned. His example/illustration on
face<br>
recognition (p.44) could easily apply to language. Let me quote the
last<br>
sentence of his article: "In doing so, we may be able to shed some
of the<br>
contentious history that has plagued our discipline for years (e.g.,
nature<br>
vs. nurture; innate vs. learned), and embrace new theoretical and
empirical<br>
approaches to human development and brain function."<br>
<br>
Sincerely<br>
<br>
Ping Li<br>
***********************************************************************<br>
Ping Li,
Ph.D.
Email: ping@cogsci.richmond.edu<br>
Department of
Psychology
<a href="http://www.richmond.edu/~pli/" eudora="autourl">http://www.richmond.edu/~pli/</a><br>
University of
Richmond
Phone: (804) 289-8125 (office)<br>
Richmond, VA
23173
(804) 287-6039 (lab)<br>
U.S.A.
Fax: (804) 289-1905<br>
***********************************************************************<br>
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