[From Rick Marken (950530.1030)]
Bruce Abbott (950529.1955 EST) --
I haven't read it ["Mind Readings"}. Why don't you quote a paragraph?
Well, I just ordered Nachtigall's book through interlibrary loan. Maybe now
you'd be willing to take a look at "Mind Readings". I am rather sorry that
you haven't read it since you are certainly in the target audience
(scientific psychologists with an interest in PCT). William T. Powers said of
"Mind Readings" in the Forward: "This is a book that can show a willing
psychologist how to do a new kind of research". Are you willing?
Joel Judd (950530.0830 CST) to Bruce A. & Rick M.
my hypothesis is that you two are not controlling for understanding at all;
Possibly true. I honestly was interested in seeing descriptions (like
Avery's) of PCT-like research in the insect behavior literature. Perhaps my
response to Bruce's description of fly-landing behavior should have been
more positive -- like "yes, it sounds like Nachtigall's book is all about
how insects control". Would that have been more understanding?
Bill Powers (950530.0945 MDT) to Bill Leach (950529.21:34) --
I've been waiting for someone to explain to Bruce why the Nachtigall
description was not a good PCT description, but as you can see, I have
finally provided the explanation myself. That would have been an easy way to
avoid the squabbles. I can only conclude that there is some other goal
involved, like showing who knows most about PCT. What a bore.
Actually, I thought I had explained why Nachtigall's description was not a
good PCT description. Not nearly as well as you did, perhaps, but I thought I
had mentioned the absense of any evidence of disturbance resistance. Anyway,
I have no interest in showing who knows more about PCT. I LIKE it when
people understand PCT -- and I like it even better when (like Avery and Tom
and you) they understand it better than me. I will try to do a better job of
explaining why things (like Nachtigall's description) are "not good PCT" (if
they are not).
I thought I had been doing an OK job of explaining (and demonstrating) my
points when I disagreed with people about PCT but I'll TRY to do better in
the future. I don't know if you have noticed but a lot of squabbling still
happens AFTER we explain why something or other is not good PCT. For
example, there was quite a lot of sqabbling about "control by consequences",
after a rather long sequence of computer demonstrations of the impossibility
of control by consequences.
As you said, push on a control system, it pushes back. Explanations are still
"pushes" if they disturb a controlled variable.
... but I was also wrong about Hans' model -- it does control
Hans Blom (950529) --
Thank you. So does it or doesn't it?
Apparently it controls better than I thought. I evaluated control using a
simple-minded application of The Test. I compared the variance of xt to the
variance of the disurbance to xt (ft*sin(run/5)), where both variances are
measured as RMS error. Under some (but, it turns out, not all) circumstances,
the variance of xt is less (but not much less) than that of the disturbance,
indicating some degree of control of xt. But Bill tells me (I still haven't
checked this out but I believe it) that the actual level of control of xt
exhibited by the model is much greater than what I measured. Because the
value of xt is the result of an integration, the open loop variance of xt
(even without the disturbance) is apparently 10 times greater than it is when
xt is part of the model based control loop. I have to measure the open loop
variance of xt and compare it to the closed loop variance to evaluate the
actual level of control of xt. But, if Bill is correct (and he is correct
about almost everything except my goals in CSG-L discussions;-)) I will find
that the open loop variance of xt is 10 times the closed loop variance.
So Hans' model-based control system does control xt. What is unquestionably
true is that the system's control of xt occurs becuase there is a perceptual
representation of xt; without the perceeption of xt, there is no control.