[From Rick Marken (960110.2200)]
Bill Powers (960110.1200 MST) --
My point was that identifying _any_ variable in a closed loop as "the
cause" is arbitrary, and wrong.
A fact which Bruce can demonstrate to himself by replicating the
"Cause of control movements" experiment described in chapter 3
of "Mind Readings".
Bruce Abbott:
There is a simple test that will distinguish which is correct: apply a
load to the crankshaft.
Bill:
The PCT model would fail in this case...This is not a control system.
And we are back to the fact that PCT is a model of _control_; a control
model is applied when we know that control is happening; that is, we
know that a variable is under control and that it is the organism that
is doing this. Reinforcement theory -- including Killeen's version
thereof -- is not a model of control because reinforcement theorists
don't know what control is; therefore, they have not done any research
aimed at determining whether organisms control and, if so, what they
control.
Bruce:
The difference between these views (control and reinforcement] has
little to do with what is actually producing the power to turn the
crankshaft. The difference is in the nature of the systems, whether
equilibrium or control.
Bill:
It is not a difference in views that makes the difference: it is the
organization of the system. A control-system model would be rejected
by the Test...no control system.
And we are back to phenomena again. If there is no controlling going
on (as revealed by The Test) then there is no need to consider control
theory as a model of the observed behavior. Since reinforcement
theorists have never done The Test to determine whether organisms
control, they have never seen the need to develop a control model.
The methods used in EAB (the research arm of reinforcement theory)
are designed to determine how organisms respond to causa inputs; so
models of the "behavior" observed in these experiments are attempts
to explain how organisms respond to inputs. Since organisms behaving
in a loop don't respond to inputs (inputs respond to the organism
_while_ the organism responds to the same inputs) reinforcement
models are irrelevant to the behavior of organisms.
It all comes back to the fact that the phenomenon of control has simply
not been studied by conventional psychologists; reinforcement
theorists don't even know that organisms (besides themselves) control.
This is why the first order of business for students of living control
systems should be to determine whether organisms in operant situations
are controlling and, if so, what they are controlling.
But nobody seems to want to do experiments anymore. Everyone's a
theorist. Doesn't anyone care anymore about what they're developing
a theory _of_?
Bill:
The argument between reinforcement theory and PCT is not a
dispute over which part of the loop is really the cause of behavior. It is
an argument about whether ANY variable in the loop should be
considered as a cause of the loop's behavior.
And, again, this is an argument about phenomena, not theory. If organisms
actually exist in a loop (if a closed loop relationship between organism
and environment is a real phenomenon) and if the behavior of this loop is
stable (another phenomenon) then these organisms ARE controlling some
aspect of their sensory input. Organisms pretty obviously do exist in
a closed loop (we can see that what occurs at their sense organs depends
continuously on what actions they are taking (how they are oriented, how
they are moving) and what actions they are taking depends on what occurs
at their sense organs.
So it's a pretty sure bet that PCT does apply to behavior; it's also a
sure bet that any theory that tries to identify one variable in this
closed loop (such as reinforcement) as a cause or "selector" of behavior
is wrong -- and will make the wrong predictions of the behavior of the
loop.
If Killeen's model actually is a closed loop model then it is either a
positive feedback model (which is stable only when the loop gain is less
than 1.0) or a negative feedback model. If it is the latter, then it's a
control of perception model, and it doesn't compete with PCT; it _is_
PCT. If, however, Killeen's model actually is PCT, then it is beyond
me why EAB researchers haven't been busy testing to see whether the
variables controlled by the model are what organisms actually do
control. Since there is no research aimed at determining controlled
variables in EAB, I'm pretty sure that no reinforcement model --
including Killeen's -- is a control model.
I wonder if everyone out there is a theorist? Aren't there any folks
who like to set up experiments that let us see if what our theories
say happens really does happen?
If not, then OK. Here's my contribution to the reinforcement/control
theory debate. Here is my derivation of Kileen's reinforcement model:
N = trunc(exp(-jr/b)*cos(Pi*F/s))
where r is reinforcement rate, b is behavior rate, F is the size of
the reinforcements (mg), s is seconds and N is the number of angels
that can dance on the head of a pin.
Best
Rick