[From Bruce Abbott (990331.1425 EST)]
Rick Marken (990331.0940) --
Bruce Abbott (990330.2240 EST)
No, it's a scientific theory. No less. No more. It
posits a particular organization of the nervous system that
may or may not be correct in various ways.
It also very explicitly includes a description of how effects
produced by the nervous system affect the inputs to that system.
I haven't seen that. Under PCT, how do effects produced by the nervous
system affect the inputs to that system? (Specific proposal please!)
How outputs affect inputs falls out of the physical organization of the
system; it is not an additional property of the theory. Furthermore, the
proper analysis of such a system is not a spcific proposal of PCT (which
merely posits that the system in question is a control system) but of
general control theory, for which the appropriate analytic tools were
developed. PCT is just an application of general control theory to a
specific proposed control structure.
PCT correctly represents the behaving system as two _simultaneous_
equations, one characterizing the nervous system and the
other characterizing the environment in which that system operates.
PCT correctly represents the behaving system in this way when the behaving
system can be correctly described in this way. When the system operates as
an open loop system, or in some other fashion (e.g., an equilibrium system),
it does not.
So your assertion comes down to saying that I am committed to
an open-loop analysis of behavior, whether warranted or not.
You are committed to an open loop _model_ of living systems.
The analysis techniques you advocate (the one's described in
your methods textbook) are based on that commitment, which is
not warranted because you know that open-loop (including
sequential state) models of behavior are wrong.
Amazing how you know me better than I know myself. I didn't have the
faintest idea! But I shouldn't be surprised, as you frequently claim to be
a mind reader. I think you really believe you are.
I would say that I am "committed" to employing whichever
analysis seems most appropriate in a given case, given the
You have never used (or published research based on) an analysis
appropriate to studying the behavior of a closed- loop control
Please review my extensive posts to CSGnet over the past four years,
especially those in which I post both computer models of control systems
and, where the study was empirical, data that the model has been fit to.
That should quickly disillusion you of the notion that I have "never used an
analysis appropriate to studying the behavior of a closed-loop control
As for publication, I have yet to find data that are well fit by a
control-system analysis, and some that appear to contradict one. You want
me to publish _those_?
You, on the other hand, are (in my view) "committed" to PCT,
which means that you will move mountains, if necessary, to make
the available evidence appear to fit the theory.
Fortunately, I don't have to. The available evidence fits the
theory to within a percentage point.
Your "available evidence" shows that when participants are placed in a
situation in which they must control something in order to perform the
required task, that they control it, and do it very well, thank you. This
is hardly surprising and it is no miracle that control-system equations do a
fine job of fitting model to data.
It means that you will be hyper-critical of any empirical result
that is incompatible with the theory
Here's a nice, well-documented example that Bill P. provided of this sort of
response (you do the same, but this one comes to mind). Tinbergen and
Lorenz observed that if the egg of a graylag goose rolls out of the nest and
stops within reach of the goose that is incubating the eggs, she will stand,
reach out with her bill, place the bill on the side of the egg opposite her,
and use the bill to roll the egg back into the nest. The crucial
observation is that if the experimenter contrives to snatch the egg suddenly
away while the goose is in the process of retrieving it, she continues as if
nothing happens, pulling the bill along the ground toward her and tucking
the now imaginary egg between her legs before sitting down. This is an
observation by reliable observers, but it doesn't fit the PCT view of
things, so Bill's response was to deny the validity of the observation. As
I said, if the facts don't agree with the theory, dispute the facts, not the
I certainly would be surprised to find an empirical result that
is incompatible with a control of input model of behavior. Do
you know of any. I've been asking for such evidence for years;
I've never seen any.
There was this long-standing belief, based on PCT, that increasing the
response requirement on a reinforcement schedule would result in a
compensatory increase in response rate. I think you went so far as to state
that this clear prediction of PCT provided a critical test of PCT against
reinforcement theory, which predicted the opposite result (decreased rate of
responding with increasing response requirement). I ran the required study
and reinforcement theory won. The overwhelming response from the PCT gurus
was "oh." Nothing more came of it. However, it turns out that the
experiment provided a crucial test only for reinforcement theory. PCT can
account for the result (after the fact) no matter which way it turned out.