Kinshuk (kinshuk@ieee.org)
Thu, 5 Aug 1999 11:39:20 +1200
From: Kinshuk <kinshuk@ieee.org> Subject: Discussion paper: Technology and the Biological Basis of Learning Date: Thu, 5 Aug 1999 11:39:20 +1200
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Dear Colleagues
I would like to thank Dr Martin Owen for moderating discussion on the
theme "Preparing teachers and trainers for the C21st" despite problems
with IFETS listserver. Unfortunately Dr Bruce Homer, who was supposed
to summarise the discussion, had already had travel plans just after the
scheduled discussion period and therefore he could not participate in
the discussion.
Now we are moving towards our August month's discussion on the theme
"Technology and the Biological Basis of Learning" moderated by Robert N.
Leamnson of UMass Dartmouth, Massachusetts, USA and summarised by Muhammad
Betz of Southeastern Oklahoma State University, USA. The discussion would
run till 20 August.
Please find below the pre-discussion paper.
Regards.
Kinshuk
IFETS Coordinator
** Discussion paper **
The intent is to examine any and all technologies and all aspects of
instructional design as a function of their effect on the learner
considered as biological entities.
Biologists have a somewhat down-to-earth understanding of the
learning process and speak of it in terms of biological processes. As
Henry Plotkin said "When we come to know something, we have
performed an act that is as biological as when we digest something." I
have prepared then, a somewhat long background paper on what
might be called the biological basis of learning. In it I propose several
questions that might be considered, but as always, you are limited only
by your imagination.
"Instructional Technologies and the Biological Basis of Learning"
In these opening remarks I will take it as given that all instruction,
whether by lecture, book writing, or other technology, has as its
purpose that someone learn something. And as we were made aware
in May, how much learning goes on is in part at least a function of the
design of that instruction. The intent of the present discussion is to
focus concentration on the learning end of the process of education.
The questions posed are:
1) Can we agree that, no matter the format of the instruction, or the
nature of the help provided by others, learning is essentially a private
event achieved by the individual learner?
2) Can we agree that learning, difficult to understand as it might be, is
not totally mysterious, but must involve the brain and is therefore a
biological process?
3) Can a better understanding of brain function and the biological
nature of learning help in the design of instruction, no matter the
technology?
As background for the discussion, here is some contemporary biology-
-some fact, some theory--that will serve to support the idea of
considering learning to be a biological process.
The adult human brain is several times the mass it was at birth. Even
so, the number of neurons, the cells that pass signals, is virtually the
same in the adult as in the newborn. A great deal of the increase in
mass is due to the growth of the individual neurons in the form of long
projections called axons, and the protective cells that surround them.
The development of the mental and motor faculties we think of as
human is a function of the connections between neurons and not so
much on the absolute number of neurons. And it is the axons that
make the connections (synaptic junctions). Because a neuron can have
a large number of axons (signal senders) and dendrites (signal
receivers) it has been estimated that the average neuron would have
1,000 connections to other neurons, with some having perhaps 10,000.
With all that in mind one might be tempted to believe that maximizing
the number of connections would result in maximizing human faculties.
But the fact is, small children whose ability to reason, abstract, and
articulate is well below that of an adult, do in fact have many more
synaptic junctions than the adult. The explanation for the apparent
anomaly comes from several discoveries that are comparatively recent.
1) The budding and subsequent growth of new axons (potential
connections) is exuberant (Jean-Pierre Changeux's term) in the young
child, but in fact probably never really stops until death. The
significance of that fact is that even the adult brain is an active organ
constantly growing neural projections and making new connections.
It's not a "hard wired" structure, like a computer, that must be used "as
is."
2) Axonal budding and growth is not particularly well directed. The
axon is not "trying" to get anywhere in particular. While certain
chemical gradients prevent it going willy-nilly where it may, it does not
have a specific target at which it is "aimed." Consequently, budding
neurons make many useless and unproductive connections to other
neurons.
3) A connection (synaptic junction) is not, however, necessarily
permanent. One of the more significant discoveries of
neurophysiologists is that all synaptic junctions are not equal. Some
are physically larger, tighter, and are said to be "stable," meaning that
one is likely to have them for life. Some pathways, then, do become
hard-wired. Other junctions between neurons are temporary. Many
axons regress or degenerate after making a temporary connection.
Such junctions are said to be labile.
4) The factor that determines whether a connection will degenerate or
become hard-wired is the frequency with which it is used. Signals
passed over a particular junction--even a labile one--have the effect of
enlarging and strengthening the connection. Used frequently enough,
a labile synaptic junction becomes stable. It's probable that most labile
connections do not produce anything potentially useful, or else they do
not get used, and so degenerate (use it or lose it).
A Theory of Learning
Explaining learning in terms of stabilizing useful circuits through
repeated use might indeed be a "just so" story. But there is nothing
about this theory that leads to any untenable conclusions. It has
considerable explanatory power, and the testable predictions it makes
have been verified at the cellular level experimentally. It is entirely
compatible with practical experience that shows that we remember
things more readily and accurately the more times they are experienced
(although the relationship is probably not linear). Musicians, for
example, are well aware of the efficacy of practice. And because the
patterns formed through multiple connections are unimaginably
complex, some pathways and sets of pathways are used not just for a
single process (like remembering your phone number) but get used in a
variety of situations in varying combinations with other pathways.
That interesting phenomenon might explain our wonderful ability to
abstract. If the same set of pathways gets used when encountering
dozens or hundreds of disparate events, it might be that there is, in
fact, something common to all those events. When we induce a
"general rule" from specific events, it could be that we are using the
neural paths that are common to all these events, but not those paths
that would identify any single episode as such.
The Modular Brain
Most of us have had the embarrassing experience of getting to the
bottom of a page only to discover that while our eyes were reading,
our consciousness was elsewhere. We can recall what we were
thinking about, but nothing of what we were reading. Laboratory
research again provides an explanation. The whole brain is not
involved equally throughout in each and every mental task. The brain
is a modular device with clusters of cells dedicated to certain types of
activity. The modules that enable vision, and even the recognition of
words, are not necessarily or in all cases corresponding with the
thinking modules. It takes some effort to get different modules to start
comparing notes. Sometimes someone can hear accurately every word
spoken to them, but not understand the cognitive content because they
were not "thinking" about what was said. (It has even been suggested
that some peoples' speech suffers from a similar problem. We've all
heard the old chestnut about ideas going from the teacher's notes into
the students' notes without passing through the head of either. Well,
something had to pass through some part of the brain, it just wasn't the
thinking module.)
There is even a biological explanation for "paying attention" to
whatever is stimulating the brain. When interest, need, or curiosity
prompts us to pay attention, as well as observe or listen, the frontal
parts of our brain become active. There are two (at least) notable
effects. Axons from the frontal neurons have found their way to other
parts of the brain. These axons sometimes attach to other axons
(instead of dendrites--the more typical situation). These axon-to-axon
connections act as switches to either attenuate or enhance the
probability that a signal will get past the next junction (these are called
"gating signals"). When we are "concentrating" the frontal neurons
attenuate signals from sources of distraction, such as extraneous noise
or things moving in the periphery of our vision. But they also promote
signal passage in the thinking modules, the parts at work when we are
trying to make sense of something. So our grandmothers were on to
something when they told us to concentrate, and repeat whatever it
was we wanted to learn.
If this model has merit (and it seems to be the only non-mysterious one
around) it should prove beneficial to consider it when designing
instruction. We would not see student brains as computers ready to
process over hard wired circuitry any program we feed them. When
learning, the brain is not so much being used as it is being changed.
Learning stabilizes circuitry that would otherwise degenerate and be
lost forever. What kinds of instruction might force the use of labile
junctions, repeatedly and with concentration? What kinds of designs
might be counter productive, distracting the mind instead of helping it
to concentrate? What kinds of instruction might inspire a student to
learn something she has no natural interest in?
And so......
"The time has come, the Walrus said,
to talk of many things.
Of books and sites and the Internet,
of what the synapse brings.
Why fore digital instead of ink,
and whether the neuron sings."
(with appropriate apologies)
Bob Leamnson
UMass Darmouth
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