[Avery Andrews 931010.2030]
(Rick Marken (930930.2100))
Indeed, it really is quite remarkable. Given that these people are
supposed to be able to understand differential equations and nonlinear
dynamics, their obtuseness is prettty hard to think up innocent
explanations for.
>It is trivially easy to model this "coordinative struture"
>using PCT. I leave the creation of this model as an exercise.
I already done it (my `lips' program, primitive tho it is.
I think that the chain of errors that leads them to fail to see feedback
here goes something like this:
1) adopt an event-based view of control theory (c.f. the assertion
in F&T 1978) that you look up a correction for a given error
in memory.
2) then draw the conclusion that 2nd order feedback can't work, since
a numerical error of 3 in the value of the 2nd order percept
could be produced in all sorts of different ways, so that the
table-lookup can't work (F&T 1978 (Stelmach vol.), F&T 1980
(Butterworth vol.).
So `event-based' thinking is a major culprit, imho.
It's worth pointing out than none of the coordinative structures
discussed in these and the 1984 paper (Kelso et al., J. Exp. Psych: HPP)
fall outside the actual limitations of the Powers 1973 2nd order
feedback systems. E.g. protruding your lips or lowering your larynx
will always make the resonating cavity longer, so there's no need
for `smart' or variable (reorganizable) output functions.
Also, upon rereading the 1980 (Butterworth vol.) article, I note that
there are some references (p. 406) to studies where people anesthetized various
things and studied the effects on the compensations - e.g. went further
in applying the Test. F&T allude to `conflicting interpretations' &
don't say anything specific about what was found. So I'll be checking
it out pretty soon. One of them is:
Abbs, Folkins and Sivarajan (1976) `Motor Impairment Following Blockade
of the infraorbital nerve: .... Journal of Speech and Hearing
Research 19:19-35.
I suspect that Abbs was on the right track, but got snowed & blown off
course by Kugler & Turvey.
>The "remoteness" of the responding site
>is, I believe, supposed to rule out a feedback control model --
I hadn't noticed this bit. Maybe this is the immediate source
for Abbs & Winstein's (1988) assertion about the `technical definition'
of feedback (Human Attention and Performance 13).
Avery.Andrews@anu.edu.au