Believe it or not

[Rick Marken (920328 8:30)]

Well, nothing seems to be getting from me out to the net,
and nothing is getting in to me from the net. I'm going
open loop here. But in the spirit of showing that open loop
behavior can happen, I will generate a brief, open loop response.


Gary Cziko (920327) asks:

Is this what "motor control" researchers actually believe we do--throw our
limbs around with pre-computed initial forces and then see where they end

Yes. Strange but true.

This seems so obviously absurd I can't believe anybody would hold such
a view.

That's why I think there is an agenda deeper that "understanding
human nature" at work here. The idea that negative feedback might
be fundementally involved in all behavior is a real disturbance to
these people.(They will allow that feedback might be necessary to do
some minimal tidying up of behavior -- but the main thrust of all
research on how organisms behave is to find evidence for and
explanations in terms of open loop systems. If PCT is a religion
then conventional psychologists are members of the rival church).

If people put forth such purely
open-loop models, wouldn't it be very easy to show how such a model can't
work due to the laws of physics?

Well, yes. But if nobody is listening then all the demonstrating in
the world won't make much difference. And these people are sometimes
pretty clever about inventing "red herrings" that seem like reasonable
responses to these demonstrations of the problems with their models
(they rarely build working models anyway, by the way -- at least, not
models that work in real environments). The "motor control" area does
seems like the place where PCT can administer the most concrete
coup d'grace to "open loop" models of purposive behavior. But these
"open loop" theorists are controlling for a principle. Maybe it's
"science abhors teleology" maybe its "physical models are REAL science").
but they are controlling -- and control systems don't just revise
their references (in this case, for principles) when there is a
disturbance; they PUSH BACK -- and these people are VERY effective
at pushing back. The content of their pushes may seem absurd to
you (and to me) -- but they work for them (and their audience -- which
is controlling for the same principle). It's actually a very
interesting phenomenon in itself (if it weren't also so disturbing
to some of my own principles).




Richard S. Marken USMail: 10459 Holman Ave
The Aerospace Corporation Los Angeles, CA 90024
(310) 336-6214 (day)