A Fly In His Ear

[From Rick Marken (950527.1600)]

Bruce Abbott (950527.1320 EST)--

Me:

I have tried to answer the first part of your argument by arguing that
PCT is not about the same phenomenon that conventional theories of
behavior are about. Conventional theories are about "behavior"
which is tacitly assumed to be caused results of action; PCT is about
controlled results of actiony -- results that are brought to reference
states and protected from the effects of disturbance.

Bruce:

I must have missed something here, because I thought PCT was about
behavior, just as conventional theories are about behavior.

Not quite. An important (the most important, I think) point of PCT is
that the word "behavior" is ambiguous. It is typically used to refer
to any measurable or classifiable result of an actor's actions.
PCT shows that it is important to distinuish between actions,
controlled results and uncontrolled results. Without making these
distinctions, all behavior is treated the same -- a caused result of
action. The conventional, "operational definition" approach to deciding
what constitutes a person's behavior treats any result of actions as an
instance of "behavior; changes in the distance between my fingers and the
ceiling is as good a measure of my behavior (especially if it yields
good results in an experiment) as are the letters I type. PCT explains
why that point of view is wrong. PCT is about behavior -- but only
when behavior is understood to be controlled results of action.

I am suggesting that we select some interesting behavioral
phenomena for which a conventional explanation has been offered
and research those phenomena using standard PCT tecnology, such as
applying "the Test" for controlled variables. The resulting model
would be a model of the organism, not of the organism's behavior.
This model could then be "run" under the conditions in which the
behavioral phenomenon of interest occurs; if at all valid, it should
then demonstrate said behavioral phenomenon.

I think this is a GREAT idea and I heartily endose it. Indeed, I thought
this what you were going to be doing with those rats.

I guess I have been under the mistaken impression that you have been
suggesting that there is something to be learned about control systems
from the "interesting behavioral phenomena" that we decide to explain
with PCT. Of course, as I now see you know, we can learn nothing at all
until we start testing for controlled variables

Try reading Nachtigall: 40. How is flight velocity regulated? (Pp. 134-
139) It has a familiar ring to it.

See, this is the kind of thing that confuses me. Flight velocity is a
perception of the observer. How does Nachtigall know that it is controlled
(regulated) by the fly? Just because someone uses a control model to
explain what they observe doesn't mean that they are using PCT, as I'm
sure you are aware. If Nachtigall didn't test for controlled variables,
then his research is, of course, of no use to PCT. I saw no evidence in
your quotes from Nachtigall that he did any testing for controlled
perceptual variables. Perhaps there was some quote I missed that described
some controlled variables and how they were detected?

Nachtigall seems to have described some very interesting behavioral
phenomena. But, as you know, you can't learn anything about control
systems just by looking at "interesting behavioral phenomena". But
you keep recommending the Nachtigall book as one I should look at
for examples of PCT research. See why I'm confused?

Bill Powers (950526.1605 MDT)--

It occurs to me that we're using the word "how" differently, in the
question "How does the fly land on the ceiling?" One meaning is,"
Tell me all the things that we can see happening as a fly lands on the
ceiling." In the other meaning -- which is the one I automatically
assume -- the question is "What is going on inside the fly which
would account for what we see happening?"

Bruce Abbott (950527.1410 EST) --

Tell that to Rick Marken. He doesn't get the distinction.

I understand the distinction and I know that you were talking about
"how" the fly lands in the first sense, viz. "describe all the things that
we can see happening as a fly lands". I guess I was under the mistaken
impression that you were saying that we could tell something about
"how" the fly lands, in the second sense -- viz, "what is going on inside
the fly which would account for what we see happening" -- by watching
"how" it lands in the first sense -- viz. "by looking at all we can see
happening as a fly lands".

I agree that Nachtigall's description of the fly's landing pattern does
not tell you what variables the fly is controlling ... I though I'd act like
a good control system and "push back" by reminding everyone of
Nachtigall's control-system analysis, offered in the same book.

You're confusing me again. You agree that Nachtigall's description of
the fly's landing pattern does not tell us what variables the fly is
controlling. So of what possible value is Nachtigall's control-system
analysis? I could build a control system model of an apple falling
from a tree but that would not be evidence that I understood the nature
of the controlling done by falling apples (they do none, of coursey).

In reference to Bill Powers (950527.0950 MDT) you say:

Illuminating discussion of the difference between the external
description of behavior and the variables used by the organism (and
model) to control perception.

So you seem to have understood and agreed with what what Bill had
to say. But then you go on to say:

I agree that Nachtigall's description of the fly's landing pattern does
not tell you what variables the fly is controlling ... I though I'd act like
a good control system and "push back" by reminding everyone of
Nachtigall's control-system analysis, offered in the same book.

This is the kind of thing that keeps puzzling me, Bruce. Bill's post was
about how Atkeson and Hollerback made detailed measures of "how"
(in the first sense of "looking at all we can see happening") people
move their hand in the vertical plane. In other words, Atkeson and
Hollerback did for hand movement what Nachtigall did for fly landing;
they gave a detailed description of how it happens (ie. what happens).
With respect to this approach, Bill says:

The path which Atkeson, Hollerbach (and many others at MIT and
elsewhere) are treading is a blind alley, because no matter how
carefully the observations are made and the invariances are
calculated, there will be no hint of the control-system organization,
the SIMPLE control-system organization, that (I claim) is actually
creating the observed trajectories

I know that you understand what Bill is saying here and why he says it.
It is an EXTREMELY important point. So I wonder why you would
want to remind everyone of Nachtigall's control-system analysis.
Since Nachtigall studies fly landing the way Atkeson and Hollerbach
study limb movement, it is not clear how Nachtigall could have gotten
hints about the control-system organization that is actually creating
the landing behavior when Atkeson and Hollerbach could get no hint of
such an organization from their trajectories .

I must not be understanding you correctly when you tell me to look
at Nachtigall's book for PCT research. I'm sure what you must mean is
that it might be a good idea to go back and look at Nachtigall after we
have done the research necessary to develop a reasonable PCT model of the
controlling done by a fly. And I agree with you-- that would be an
excellent idea. But, of course, unless Nachtigall tested for controlled
variables, it makes no more sense to look to Nachtigall's data for hints
about the control system organization involved in fly landing than it is
to look at Atkeson and Hollerbach's data for hints about the control
system organization involved in limb movement.

I'm glad that you understand all this and I'm sorry for any misunderstandings
on my part. There must be a fly in my ear.

Best

Rick