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Posted-Date: Tue, 18 Aug 92 13:40:25 PDT
Newsgroups: bit.listserv.csg-l
Date:         Tue, 18 Aug 1992 13:40:25 PDT
From:         marken@AERO.ORG
Subject:      interactionism

[From Rick Marken (920818.1300)]

penni sibun (920818.1200) says:

>that's what interactionist approaches try to get at:  an
>organism doesn't have to posit its goals _de novo_ and figure out how
>the satisfy them.  there's already a lot of stuff around that
>facilitate doing what needs to get done.  as agre puts it, we ``lean
>on the world'':  our roads and cars are culture are designed to make
>driving down the road a plausibly easy thing to do.

I think the we (PCTers) and the interactionists may just have a
fundementally different notion of what it means to understand
something.  I don't get any feeling of greater understanding about how
behavior works from the suggestion that there is already a lot of stuff
around that  facilitates doing what needs to be done. The way I parse it,
it sounds like you are saying that the environment (or our perception
thereof) -- which is the stuff around-- guides (facilitates) behavior
(what needs to be done). This sounds like a verbal version of the sr
explanation of behavior that you clain interactionism is not. Sayingthat
we "lean on the world" doesn't help; suppose I want to (need to) point
straight forward? I can't lean on gravity to do that; if I lean on gravity
I'll generally end up pointing down.  I really just don't get this
interacting business. As Mary Powers pointed out, interacting suggests
that the actor and environment are cooperating to produce what needs
to get done. But the enviroment doesn't care whether what needs to get
done, gets done or not;  the environment is just there, doing its own
thing (I think; at least that's the model of the environment that we get
from physics -- and it works extremely well). The road doesn't care
whether you stay on it or not.  Whether the road makes it easy to drive
or not depends on what YOU need to get done; some of these nice,
smooth roads may make it hard to give the kids a fun bump in the back
seat.  Whether the environment is easy or not makes sense only inb
terms of one's aims in that environment; I think.

>maybe someone can explain this to me.  when you say ``signal'' or
>``variable'' or ``percept'', it has connotations to me of a unified
>thing, like a tone, or a light intensity.  but when i look at the
>road, i am not perceiving something like a tone.  if you can explain
>how all the stuff my eyes take in can be a single unified thing, maybe
>i won't find it so oversimplified.

I think this is an important point.  I think a number of people have a
problem with this. I take it for granted that perception is just what
afferent neural firing looks like when you are a brain (which we are). I
imagine that every different perception we have is the firing rate of a
single neuron. My mental model of this is the receptive field. We know
that certain neurons (in the lateral geniculate nucleus, for example) are
"looking" for particular patterns of light on the retina. For example, the
firing rate of a particular neuron might increase as a line on the retina is
rotated from vertical to horizontal. So this neuron is a horizontal line
detector. The faster this neuron fires, the more the perception it is
having is like a horizontal line. The orientation of the line on the retina is
the input variable, the rate of firing of the neuron is the perceptual
variable. Subjectively, I imagine that the change in firing rate is
experienced as a change in orientation.  The rate of neural firing, by the
way, is the "perceptual signal" and we also call it the perceptual variable
(because it varies). Obviously, I could control this variable if I could
influence the orientation on the retina of the cause of the firing in this
neuron; and this is, indeed, how neural control systems work. As I
rotate my head (or an obhect in the world) I can bring the firing rate of
the perceptual neuron (the perecptual signal) to the reference level that I
specify. Note that the reference level is also a neural firing rate; all I'm
doing is telling (with the reference rate) at which rate the perceptual
neuron should fire. The consequence of bringing the perecptual neural
rate to the reference heural rate is to create some objective state of affairs
-- such as orienting the horizontal of the computer screen with the
horizontal line connecting my eyes.

I imagine that there are many (millions?) of neurons that detect all kinds
of different properties of the world -- simultaneously. How you wire up
a neuron to sensors so that it fires in proportion to, say, the degree of
honesty in a relationship, we don't know. But we do imagine that
something like this must be what is done by our own brain. I imagine
that when I perceive a person as honest, that very abstract, temporally
and spatially defined percept is computed by the neural nets in my brain
and results in a level of firing in some neuron (the honesty detector?);
and that level of firing is what I experience as the perception of honesty.


This is the part of the model that gets complicated (and interesting) -- for
a nicer development see Powers "Behavior: The control of perception".

Best regards


Rick


     **************************************************************

Richard S. Marken                   USMail: 10459 Holman Ave
The Aerospace Corporation                   Los Angeles, CA 90024
E-mail: marken@aero.org
(310) 336-6214 (day)
(310) 474-0313 (evening)
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