NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/bit/listserv/csgl/2040

Text File | 1993-01-03 | 7.0 KB | 131 lines

Comments: Gated by [e-mail]
Path: sparky!uunet!paladin.american.edu!auvm!MCIMAIL.COM!0004972767
Message-ID: <41930104020614/[e-mail]>
Newsgroups: bit.listserv.csg-l
Date:         Mon, 4 Jan 1993 02:06:00 GMT
Sender:       "Control Systems Group Network (CSGnet)" <[e-mail]>
From:         Hortideas Publishing <[e-mail]>
Subject:      ON PURPOSE; devil's advocacy
Lines: 120

From Greg Williams (920103 - 2)

>Bill Powers (930103)

>However, I am not going to write another book. You and Rick and
>others are going to write it. When I try to write another book,
>it turns out to be BCP all over again. The reason is that my
>background is too limited to write anything else. _On Purpose_,
>if it follows the outline of [animism, anti-animism, control]
>should contain lots of references to real things that people have
>believed or have been thought to have believed, with citations
>and quotes and all that scholarly stuff that makes an interesting
>story out of a bare recitation of principles. I can't do that.
>But you and Rick can.

Whoever writes the book will find a lot of relevant scholarly stuff in Hans
Kelsen's SOCIETY AND NATURE: A SOCIOLOGICAL INQUIRY (University of Chicago
Press, 1943). The notes run to over 100 pages, with references to many
anthropological and history of religion papers. To wet whoever's appetite, the
chapters include Primitive Consciousness, The Social Interpretation of Nature,
The Interpretation of Nature According to the Principle of Retribution, The
Idea of Retribution in Greek Religion, The Law of Causality and the Principle
of Retribution in the Greek Philosophy of Nature, The Law of Causality in
Modern Natural Science, and Natural and Social Science. Kelsen was basically a
philosopher of legal systems.

-----

>Rick Marken (930103.1000)

>In several of his early papers,
>Bill showed that, in a compensatory tracking task, the correlation between
>input (cursor), i, and output (handle movements), o, can be nearly zero
>while the correlation between disturbance (which is invisible) and
>output is on the order of .99.

First, the disturbance isn't really "invisible" to the tracker, who sees its
effects on the cursor. No, the tracker doesn't have a global portrait of the
time course of the disturbance, but he/she can detect the current effect of
the disturbance on the cursor. Sometimes the cursor takes off upwards,
sometimes downwards, either way sometimes slowly and sometimes rapidly. I
think that some nonPCTers would claim that these are the "stimuli" to which
the tracker is "responding." OF COURSE, they would say, there is a low
correlation between the time course of the cursor position and the time course
of handle position. But there should be a high correlation between the "true"
"stimulus" (in their view), which is some function of BOTH position and
velocity of the cursor at any time (and perhaps the recent history of the
cursor's position and velocity, too) and the "true" "response" (in their
view), which is some function of BOTH position and velocity of the handle.
They would simply not buy the PCTers' identification of "stimulus" and
"response." And they would point out that the only way a disturbance could be
completely invisible is for it to be continuously zero (and, in the real
world, where gain cannot be infinite, I think PCTers must agree). So (again,
in the real world), the cursor moves a bit under the combined effects of the
disturbance and the handle movements. If it didn't move at all, the person
would move the handle so as to get the cursor to the desired place and stop
moving the handle. The little bit it DOES move gets AMPLIFIED by the tracker's
control loop, and if you looked closely at the record of the cursor movement,
you could find high correlations between the position and the time rate of
change of position of the cursor relative to the desired place, and the
position and velocity of the handle relative to the handle's position A LITTLE
EARLIER. In other words, the "stimulus" (according to the nonPCTer) is
position and velocity of the cursor relative to the desired place, and the
"response" is position and velocity of the handle relative to the handle's
position and velocity a bit earlier. For example, when the cursor starts to go
up at a high rate of speed from the desired place, the tracker moves the
handle in the direction which makes the cursor go down (starting from wherever
it is at the time) with a high rate of speed.

>Bill's demo simply illstrates in practice what the equations for a closed
>loop control system show analytically -- that the output of a control system
>depends on the disturbance to the input, not on the input itself. This is an
>amazing finding (from the conventional perspective) -- because the cursor is
>all that the subject sees -- it MUST be the cause of what the subject does.

It will not amaze those who think PCTers have identified incorrect "stimuli"
and "responses."

>Powers' little demo showed that there is no visible functional relationship,
>f, between i and o when behavior occurs in a closed loop. Obviously, this was
>a finding that would not be easy for psychologists to swallow -- seeing as
>how it would call into question the validity of virtually EVERY PSYCHOLOGICAL
>LAW that had been discovered to date.

Again, this depends on what count as i's and o's in the eyes of the beholders.
HAS ANYONE ACTUALLY LOOKED AT THE CORRELATIONS BETWEEN CURSOR POSITION AND
VELOCITY, AND HANDLE VELOCITY, RATHER THAN HANDLE POSITION?

>My "repeated output with different input" demo does this. What I show
>is that it is easy to produce virtually the same o on two occasions
>while i is COMPLETELY different on each occasion. Now the person
>claiming that there must be SOME function that produces o from i must
>find a function that can map i1, i2, ... iN (all different temporal
>variations in cursor position) with the SAME o. This is just not a
>mathematical possibility (even allowing for the slight statistical
>differences in o on each occasion).

Where is the person who is claiming that there is ONE function which maps all
of the different i's to the same o? They will say that each i has a different
function mapping to the same o, which is perfectly possible, mathematically.

>So Gary's demo quantitatively rules out the possibility that o = f(i)
>when behavior occurs in a closed loop, negative feedback situaiton.
>It PROVES that sensory input is not the cause of behavioral outputs
>-- no matter how ridiculously counterintuitive this seems.

It PROVES that ONLY if YOUR identifications of i and o are accepted.

>But will this demo convince a psychologist who is busily doing research based
>on the assumption that o = f(i). NO WAY, JOSE. S/he can always describe the
>results VERBALLY  -- invoking the shiboliths of scientific psychology --
>"stimulus generalization", "response generalization", etc -- and they can get
>back to work.

It looks as though they might contest PCTers' claims QUANTITATIVELY, too. It
all hinges on their claim that your i and o are straw variables.

As ever,

Greg