[From Bill Powes (961124.0645 MST)]

Tracy Harms (19961123.22 MST) --

What does PCT say
regarding periodic behavior? Yes, I can see how it can always be mapped as
instrumental to a (relatively?) stable reference level, but still I suspect
there is something significant about oscillation, something which makes it
morphologically distinct from other feedback structures. Breathing and
waking/sleeping look especially significant, but walking and many other
patterns are also dominated by this pattern. Are there any existing places
in the literature which anybody can point me to? (I do like the discussion
of sleep and dreaming in B:CP, but that doesn't overtly address the quality
which I have in mind.)

About the only literature I can think of is by people in the Motor Control
field, and I don't much like their solutions to the problem. They propose,
correctly I think, that there have to be oscillators and pattern generators
in what I would call the output functions. But they think this can be done
open-loop, which I don't believe. I think we also perceive in such terms as
phase, frequency, and amplitude, and can control with respect to reference
phases, frequencies, and amplitudes.

If I were to try to get this kind of behavior explicitly into the HPCT
model, I think I'd start by looking at the "event" level with the idea of
expanding it to include oscillatory or repetitive pattern control. As it
stands now, this level is vaguely associated with short, familiar space-time
packages of transitions, configurations, sensations, and intensities which
are perceived as single units, like the bounce of a ball.

I've always promised myself that I'd try a model of this kind of control,
but somehow have never got around to it. It's not hard to put together
phase, frequency, and amplitude detectors, but the details of how error
signals get turned into corrections of phase, frequency, and amplitude of
the output pattern generators have to be worked out, and I've just never
done it. Maybe I keep hoping that someone else will do it.


Bill P.


Tracy Bruce Harms
Boulder, Colorado caveat lector!