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Posted-Date: Sat, 09 Jan 93 15:32:16 PST
Newsgroups: bit.listserv.csg-l
Date:         Sat, 9 Jan 1993 15:32:16 PST
From:         marken@AERO.ORG
Subject:      Psychophysics , S-R "Part" of PCT models

[From Rick Marken (930108.1400)]

Martin -- I will get to your psychophysics post; it's a good question.
I was a "psychophysicist" and I have thought about this a bit (Tom
Bourbon was also a psychophysicist -- auditory, like me -- so it is
a rather remarkable coincidence that we both feel into the PCT trap
independently; maybe he'll have some comments on it too). The short
answer is that, although psychophysics often gives you pretty
good data (in my thesis research I was getting r2 values in the high
.80s and even the low .90s) all the research is based on the premise
that sensory input is the first step in a causal chain; and that
responses are the last. I would suggest that psychophysics could just
BECOME PCT by changing its goals slightly; PCT aims to find
controlled perceptual variables -- the dimensions of control. Psycho-
physics wants to quantify the dimensions of perception; this goal could
probably be achieved far more accurately (if it were still a goal) in the
control framework. But the measurement goal could be abandoned, I think,
since the desired perceptual "scaling" would be inherent in the control
model itself.

Greg Williams (930108)

>But I thought that the typical S-R model was construed by PCTers as containing
>reference ONLY to observable variables and as purely descriptive at the level
>of the phenomena being DESCRIBED,

This is NOT the PCT problem with S-R models. We KNOW that they do not
contain reference to only observables. In the model R=f(S) f (and probably
also S if it is the sensory variable) is unobservable. The PCTer's
problem with the typical S-R model is that it says that behavior (R) is
the last step in a causal chain that starts in the environment, at the
sensory surface or in the brain (the latter being the reason we know that
cognitive "models" of behavior are really S-R).

>So I think that, with regard to PCT models of tracking TO DATE, the
>behaviorists would have no difficulty in adopting the same models.

We KNOW that -- why do you think there are all these behaviorists
running around saying "we already know PCT" -- and not knowing that
what they know has zilch to do with what PCT is about (that the
existence of the feedback loop means that behavior is the control
of perceptual variables relative to reference states specified
inside the organism itself)? If they would have no difficulty adopting
the PCT model AND UNDERSTANDING IT why would they have so much
difficulty doing the research that tests the model???? --why don't they
try to find the variables that are actually controlled; what changes the
reference setting for that variable? I don't know of ANY behaviorist
research that has been based on an attempt to test the PCT model -- even in
its simplest form. So behaviorists might have no difficulty adopting the
PCT model -- but they seem to have considerable difficulty understanding
it and USING it.

>And they would see nothing revolutionary in PCT.

They would not, will not and do not. So???? They wouldn't see
revolutionary unless it were some mathematically incomprehensible
(to the layman) new theory that was developed to explain some new
spiritual aspect of quantum physics. If it's simple, pure and true (accurate)
 -- and if it has been sitting in front of their noses for years -- then
they think it CAN't be revolutionary -- or even different. Fine. "And
yet it turns"

>But if PCTers went on to include
>in new models some underlying hypothesized variables to generate "noise," so
>as to be able to predict cursor position adequately for True Science, then
>there would be two upshots: (1) the behaviorists' models would be genuinely
>different from the new PCT models; (2) if the new PCT models could predict
>cursor position very accurately, and the behaviorists' descriptive models
>could not, then the behaviorists would need to take the PCT models (and,
>indeed, the whole notion of needing EXPLANATORY generative models using
>underlying internal variables) seriously -- PCTers would have solved a problem
>that the behaviorists couldn't solve, and would have beat them at their own
>game.

If you would like to try this, please do; this is not a currently high
priority in my research because 1) I don't believe the "noise" will improve
the model's predictions 2) PCT already is completely different than be-
havioristic models, whether it is recognized as being so or not and
3) I don't believe it would get the attention of behaviorists even if
the noise model did improve the prediction. But it would be great if
you did this kind of modelling; maybe it WOULD work and get the attention
of "conventional" psychologists; I would really like to test your idea;
I just don't think I want (or am even capable) to do the work myself
(maybe).

Best

Rick
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