Devil's Bib comments

[From Bill Powers (930119.1430)]

Greg Williams (930119) --

RE: Devil's Bibliography

The exerpts from Schmidt make him sound like an almost-good-guy.
Actually, a good guy who is looking for whatever there is in
control theory that seemed to him usable. What he's missing is
the concept of a hierarchy of control. It's interesting that even
in 1982 he is citing the engineers' "point-to-point" method of
controlling movements, and the fact that it is computationally
expensive. This idea clearly influenced Kelso et. al. It would be
interesting to see if we could find where this approach to
movement started -- probably WAY back. The idea that a simple
analogue signal variation could drive a controlled movement with
hardly any computation at all seems to have been lost along with
analogue computers.

Is there any way to check out something about his "former
mentor," Jack A. Adams? Back in '57 or '58, Bob Clark, the late
Bob MacFarland, and I went to the U of IL to give a seminar for
O. Hobart Mowrer's graduate students. Among them, I think, was
Jack Adams. Mowrer was very taken with our concepts of "feedback
theory" as we called it then (and as the Adams in the literature
refers to it). Mowrer devoted a good part of chapter 7 of
_Learning theory and the symbolic process_ (New York: Wiley
(1960)) to our ideas. If this is the same Jack Adams, that would
be interesting, because as far as I know he doesn't cite us or
Mowrer. If it isn't the same Adams, it's not so interesting.

I just computed the minimim acceleration of Ali's fist, from the
remembered data that his jab moved about 6 inches. If this took
40 milliseconds as cited by Schmidt, Ali's fist accelerated at
187.5 meters/sec^2, or 19 g's. Obviously no control is possible
during such a brief movement, but it's easily explainable as
resulting from a step-change in the position reference signal.
The Little Man exhibits such speeds of movement when the
kinesthetic reference signal is stepped abruptly to a new
position (I set the parameters to give about 100 millisecond
movements, but the model can go faster). If the reference
position is set _beyond_ the target, as fighters are supposed to
do, the transition time to hit the target can be even less than
40 milliseconds even with the model set to go 95% of the way to
the target in 100 milliseconds.

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Bruce Nevin (930119.0844) --
RE: Schmidt

Controlling for the stop signal I assume is at a higher level
of the hierarchy, and the delay corresponds to that in the
portable demo described in BCP (extended arm is raised before
lowering it in response to signal).

Yes, that's what I would say, too.

Isn't some of their time problem due to thinking of the loop
sequentially (trial and then error and then correction in
another trial) rather than concurrently and continuously?

I agree that it is.

Poul Andersen did this sort of thing with a General Semantics
premise in the early '50s (_The World of Null-A_ f'rinstance).

Writing under the name of A. E. van Vogt? Actually I think World
of Null-A came out a good deal earlier than the '50s -- it was my
introduction to Korzybski. I remember the fizz of intellectual
excitement when I realized that the fascinating quotes used for
chapter headings came from a REAL BOOK! I spent my later high-
school years trying to develop that "cortico-thalamic pause." It
greatly improved my ping-pong game.
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Bob Clark (930119) --

I still have not got the distribution procedure well worked
out. Should I include other individuals in addition the "CSSG-
L"?

Whatever you send to CSG-L goes to all 128 (at present)
individuals who subscribe to the list. The semi-standard heading
(like the first line in this posting, way above) is put in the
text by hand as a way of identifying the sender at the start.
Most other header (and trailer) material is put in by internet
and is automatic. Some of it can be modified by users who know
the tricks ( like CC: to send copies to people not on the list).

Do you remember Jack Adams from the Mowrer symposium?
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Best to all,

Bill P.