[From Rick Marken (950601.1100)]
Bruce Abbott (950601.1040 EST) --
I used this quote as evidence that Nachtigall understood the elements of
closed-loop control, to support my thesis that insect researchers have been
aware of the concept for a long time;
What we have been arguing about, apparently, is whether to classify what
Nachtigall did as "PCT research." I thought that Nachtigall's description
of flight velocity control was very much in the PCT mold, but it turns out
that we have somewhat different criteria as to what is and is not PCT
research.
I think one problem is that you believe that an understanding of control
theory is equivalent to an understanding of PCT. In fact, understanding
control theory and understanding PCT are two different things.
PCT is about the application of control theory to the behavior of living
organisms. Control theory was around for years before Bill Powers developed
PCT. And there have been many applications of control theory to behavior
both before and after the development of PCT. What distinguishes PCT from
other applications of control theory to behavior is that PCT is based on the
idea that behavior IS control; the idea that organisms produce consistent
results under variable circumstances. Non-PCT applications of control theory
to behavior assume that behavior is a cause-effect process; control theory
is used to explain how inputs cause outputs that produce control. PCT shows
that this way of applying control theory to behavior is wrong.
So it's not control theory that distinguishes PCT as a theory of behavior;
it is the recognition that behavior IS control that distinguishes PCT. Once
you understand that behavior is control, the next step is to understand
that the proper mapping of the control model onto behavior puts perception
into the loop as the controlled variable.
So it is perfectly possible to understand control theory and not understand
that behavior is the control of percpetion. Evidence of this is provided by
nearly everything posted by Hans Blom;-) You can also find it in the
psychological literature. Two of my favorites are:
(1) T. B. Sheridan and W. Ferrel(1974) "Man Machine Systems", MIT Press
(2) E. C. Poulton (1974) "Tracking Skill and Manual Control" Academic Press
Check out Figure 9.1 (p. 177) in (1) and Figure 1.1 (p. 5) in (2). In both
cases the input to the human is an _error_. The human convenrts this error
into output that reduces the error. So error is viewed as an objective
phenomenon ("I know what's wrong when I see it!"). This turns the human into
a transfer function, conveting objective error into the outputs that reduce
error. This, of course, puts the environment (the source of error) in
control, just where psychologists always thought it was.
These books are "bristling" (Bill's felicitous expression) with engineering
terminology and the differential equations of control theory. But they are
definitly not PCT -- not even close. The reason these applications of control
theory are not PCT- - the reason they incorrectly map control theory to
behavior -- is because they are not based on an understanding of the nature
of behavior as control (see the first paper in "Mind Readings" for more
detail).
ยทยทยท
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Me:
We PCTers believe that PCT should not be required to account for most
of the descriptions of behavior provided by conventional psychology,
Why do you (Bruce or anyone else for that matter) think we believe this?
Bruce Abbott (950529.0935 EST) --
you have at least two reasons: 1) most conventional research did not
collect data that can be used to construct an adequate control system
model...2) the better approach would be to start from scratch with studies
designed to elucidate the controlled perceptual variables
My problem with this is...I see no reason why one should not explore the
controlled variables that come into play in some of the situations already
extensively studied
Bruce Abbott (950601.1105 EST) notes that I gave no response to this post and
says:
I'd very much like to know whether or not my description of your position
was accurate.
Sorry. The reason I gave no response is because there was no disturbance.
Your description of why you think I believe "PCT should not be required to
account for most of the descriptions of behavior provided by conventional
psychology" was accurate. And what you call your "problem" with that belief
was no problem for me. I too "see no reason why one should not explore the
controlled variables that come into play in some of the situations already
extensively studied". In principle, it's a great idea; in practice, it
usually requires access to data that is not available (the kind of data Bill
Powers managed to get from Verhave in order to determine the variables
controlled by the rats in his shock avoidance study) or it requires just
going out and getting data that was not collected.
There are cases where we have been able to guess at reasonable PCT models to
account for conventionally obtained data. But my experience has been that
there is just not enough known about the conditions under which the
conventional data was collected to make it possible to build a PCT model to
account for that data. This is true even when the data is fairly
noisless and involves single subjects. What we usually don't have are records
of the state of the input variables that might have been under control.
That's why it would be fruitless to develop PCT models to account for the
data obtained in, say, "stimulus control" and "classical conditioning"
experiments.
But there is certainly no law against trying to "explore the controlled
variables that come into play in some of the situations already extensively
studied." But what that means to me is going out and doing the studies
necessary to find out what variables are controlled in the situation already
extensively studies.
Best
Rick