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Posted-Date: Thu, 08 Oct 92 13:09:13 PDT
Newsgroups: bit.listserv.csg-l
Date:         Thu, 8 Oct 1992 13:09:13 PDT
From:         marken@AERO.ORG
Subject:      Re: they already know that

[From Rick Marken (921008.1300)]

penni sibun (921097.1400) --

Ah, it's nice to have you back.

>if you showed how well-known phenomena can be
>analyzed differently and novelly in yr hierarchy--*that* way you can
>make an *argument* for your hierarchy.

Actually I did that, though I didn't do it quantitatively, unfortunately
(like by showing a working model) -- mainly because the right data wasn't
available and I was not interested in doing the experment at the time --
but I might do it eventually; this was really a theoretical paper, after
all. The "well known" phenomenon was really just a finger tapping study
done by Rosenbaum (described in JEP:HPP, 1984). He had subjects make
sequences of finger taps as rapidly as possible. The result of interest to
me was that the speed limit was about 4/sec, the same as the perecptual
limit for perceiving auditory and visual sequences. My alternative theory
of what was going on (Rosenbaum had an output generation model) was that
subjects were controlling a sequences of perceptions  of finger tip
pressure. I suggested, in the paper, that one piece of evidence to support
this would come from a study the subjects' ability to perceive finger pressure
sequences that are presented to them (that are not generated by their
own taps) -- my guess is the same limit will be found. So the speed of
finger tip sequence production is limited by the ability to perceive
(and hence control) sequence -- not by limitations in the output
process. There are other experiments that I could think of -- the most
obvious would be to add disturbances to the finger movements and
see that this has little effect on the perceived sequences. But the
goal of the paper was to find evidence of perceptual control in the
existing literature -- not easy given that so much of the data is fairly
useless because it is averaged over people.

>but see, i'm not convinced, from the kinds of things you write about,
>that it's coherent for you to say ``perception is behavior.''  i think
>i can map from your model straightforwardly into one w/ pieces labeled
>``perception'' and ``behavior.''  you haven't convinced me i should
>consider the terms synonymous or what that would mean.

Believe me, I understand your problem. I've been trying to explain
and demonstrate this stuff for years and it is not easy to communicate
what I consider to be obvious points. I'm sure it's as frustrating for
you as for me. I thought I did a pretty good job of explaining in the
paper that "behavior" refers to controlled results of action; actions
are the means by which behaviors (controlled results) are brought to
their intended levels. In a control loop, the result that is untimately
controlled is the perceptual input variable. The actions used to produce
this results are not "behaviors" from the point of view of the behaving
system but they may appear to be "behaviors" from the point of view
of the observer of the system, simply because they are produced by the
system (the word "behavior" is typically used to refer to any result of an
organisms muscle actions). For example, in the "rubber band" demo, the
position of the knot is a behavior of the subject; the position of the
subject's hand is NOT (though it would be seen as such by any observer
of the situation). The position of the knot is controlled -- it is an
intentional result of the subject's actions. The position of the hand
is not controlled -- it will be moved wherever necessary to keep the
knot of target.

I think you raise an interesting point about showing how PCT is a better
model of some "well known" phenomenon than some current explanation. One
problem we have in PCT is that most of the "well known" phenomena around
are, from our point of view, not phenomena at all. We went through this
exercise some time ago when we looked, in detail, at a study of voice
onset time in phoneme recognition. It turned out that the phenomenon was
only there statistically -- at best. Maybe you could pick a "well known"
phenomenon, give the reference to the reserach article it is described
in (so we can all get a copy of the results) and we can see what PCT has
to say about it.

Best regards

Rick

     **************************************************************

Richard S. Marken                   USMail: 10459 Holman Ave
The Aerospace Corporation                   Los Angeles, CA 90024
E-mail: marken@aero.org
(310) 336-6214 (day)
(310) 474-0313 (evening)
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