[From Rick Marken (930923.1300)]
Gary: This is being sent to CSG-L only. I tried to send
it to Chris Wickens too but it bounced. What's his address
Chris Wickens says:
I find that what I "really" believe about manual
control, is not all that different from the final tenants of PCT,
outlined by Rick,
What I listed were criteria for determining whether an
approach to understanding behavior represented a parallel
development to PCT. These criteria (or "tenets" if you
prefer) were as follows:
1. Explicit statement that organisms control perceptual
analogs of variables in the "objective" world experienced
by the observer of organisms.
2. Explicit statement that organisms themselves determine
the preferred states of these perceptual variables.
3. Explicit description of a methodology like "the test"
that is designed to determine which variables are being
controlled by an organism.
I claim that the use of control theory in the study of manual
control (by the people you mention: McRuer, Jex, etc) was NOT
a parallel development to PCT because it did not meet my three
criteria (in fact, I would say that it didn't meet even one of
the three). I have read quite a lot of the manual control work.
The main focus of this work seems to be on the effects of
dynamic characteristics of disturbances on performance (measured
in terms of deviation of one external variable from another).
There is nothing wrong with this work -- it's just not PCT,
which is mainly interested in control that is dynamically
stable (probably 99% of the controlling that is done by living
systems). PCT is interested in WHAT kinds of variables organisms
control, HOW they control them and WHY.
I am not trying to distance PCT from the work of manual
controllers; much of what the manual controllers have
found is of great interest. They just haven't done any
PCT research -- the kinds implied by my three criteria above.
They did not test to determine the kinds of perceptual
variables people control (if they did, I would really like
to see the reference because I could use it for a paper I'm
writing) or why they control them (they have done work on
how people control, under the assumption -- probably correct --
that they knew what is being controlled).
Again, my argument with Greg is simply that 'manual control'
theory is NOT a parallel development to PCT; but I would be
very happy to be proven wrong about that. To show that I am
wrong (something I am used to being, so don't worry-- you
won't hurt my feelings) just point me to the chapter and
verse of the manual control literature where I can find
statements that satisfy ALL THREE of my criteria for a
parallel development of PCT. They should be easy to find if
manual control really is a parallel development, but to tell
you the truth, I've never found any. Maybe I'm looking in the