NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/bit/listserv/csgl/1014

Text File | 1992-09-15 | 7.5 KB | 162 lines

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Date:         Mon, 14 Sep 1992 13:14:46 PDT
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Subject: Re: Turing
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[From Rick Marken (920914.1200)]

penni sibun (920913.2000) says (to me):

>that's ok; i don't usually read you since i know what you're going to
>say.

ouch!

> however, you did pique my curiosity by mentioning the turing
>test--even though i knew what you were going to say ;-}.

>turing based his test on what was apparently a sort of parlor game in
>which the interrogator has to decide which is male and which is
>female.  maybe the analogy will be helpful.  how do we know if someone
>is male or female?

>if *sex* is decided in such a ``superficial'' way, then why not the
>ability to think?

This analogy rests on the assumption that behavior is to thinking as
gender is to chromosomes. Apparently, you assume that the "superficial"
signs of gender (malenes vs femaleness) are an output of chromosome structure:

xy --> maleness
xx --> femaleness

So, the "sex text" looks at observed maleness or femaleness and guesses
at the "real" sex of the person (their chromosome structure). The above
assumptions make it reasonable to think that you can "work backwards",
inferring chromosome structure from appearance.

I agree that this is just how Turing looked at his test for mind. He
assumed that "mental behavior" was an output of mental structure, and
"non-mental behavior" was what resulted when there was no mind:

mind --> mental behavior
no-mind --> non-mental behavior.

So the Turing test is based on the same idea as the sex test; look
at observed behavior and work backwards to infer whether or not the
behavior was generated by a system with a mind. If you see "mental
 behavior" then guess mind; if you see non-mental behavior then
guess "no mind".

The point of my post (if you are still reading) was precisely this:
the Turing test is Behavioristic in the sense that it assumes that
mental behavior is the OUTPUT of a mental system. This assumption
is also the basis of cognitive psychology. The idea is that
you can infer something about the ming by looking at behavior
because behavior is an OUTPUT of mind.

I brought this up because, according to PCT, the Turing test
(as Turing described it) cannot work; behavior (results that are
intentionally produced by the organism) is NOT OUTPUT -- it is
controlled INPUT (ie. perceptions. The PCT model of mind
produces a 3rd alternative to the two above, namely:

mind -->input< -- actions
      |  "behavior"      |

The mind (reference signals) specifies intended levels of input.
The system acts to keep these inputs at their intended levels (but
it does not cause these actions; these actions are caused by the
disturbance - resistant characteristics of the system).

An observer might call either the actions or the observed correlate
of the intended input the "behavior" of the system. In PCT, we reserve
the word "behavior" for the intended inputs; actions are not really
the behavior of the system since the system doesn't really determine what
those actions will be. But actions (or their side effects as seen by
the observer) are what are most likely to be seen as behavior. These
actions, however, don't really reveal what Turing is trying to get at --
whether or not he is dealing with a system with a mind.

What Turing really needs to do (if the PCT model of the system is
correct) is figure out whether or not he is dealing with a system
whose actions are aimed at protecting the state of an input
variable (a variable that is determined by a mind). To do this,
Turing would have to know that there might be a controlled variable
involved (the "input" in the diagram) and test to see if that variable
is being protected from disturbance. This process is called "the test
for the controlled variable". It differs from the Turing test only
inasmuch as it clearly specifies QUANTITATIVELY how a system with
a mind differs from a system without one; the system with a mind is
busy trying to control input variables (at least if it is the kind of
mental system assumed by PCT -- a purposeful mental system). The no-mind
system is not controlling an input.

You cannot tell whether or not a system is controlling an input by
simply watching to see if its behavior "looks" intelligent. But this
is what Turing suggested WAS possible. You "poke" at the system
(with questions) and watch to see how it responds. If the response if
judged "intelligent" then you guess that it was made by a mental system.
This approach is not only unnecessarily subjective (as you hint at in
your "sex" example) -- it is bound to give the wrong results when you
are dealing with a mental system that is organized as a closed loop
control system. The failure of the Turing test is demonstrated by
my "mind read" and "find mind" programs (since you don't read my
stuff I guess I can count on your not reading about the mind read
program in my Mind Readings book). The "find mind" program, which you
will be happy to learn is NOT written up anywhere,  is a good
example of the Turing Test. One of five numbers is actually controlling
it's position but all five are "doing" pretty complex movements. I
could have each one trace out the form of a character punched into
the keyboard -- their movement in reponse to the input is like their
response to a Turing question. I could even have only one consistently
answer correctly. But, still, all but one are generating behavioral
output. Only one is actually controlling an input -- and this is the
only one with a "mind" -- a reference for it's position. This one
is easily detected by disturbing it's position (with the mouse).

I doubt that you are still there, penni, but for the benefit of anyone
who still is, the point is the the Turing Test (as it is described in
Turing's article -- yes, I read it) is based on a behaviorist conception
of behavior -- ie. that behavior is an output generated by mind events.
PCT says that this concept of behavior is demonstrably false. So there is
no way to distinguish mind generated from non-mind generated behavior by
just LOOKING at characteristics of the behavior itself. You CAN,
however, distinguish mind generated from non-mind generated behavior
using the Powers Test (the test for the controlled variable) which
involves:
1. identifying a possible controlled variable
2. produce disturbances to the variable (events that should change
the hypothetical controlled variable if it is NOT controlled)
3. monitor state of hypothetical controlled variable under continuous
disturbance
4. look for lack of effect of disturbance
5. if there is no effect, make sure system being tested can perceive
the variable (control stops when variable is obscured) and can
effect it

Turing was a smart, swell guy and all but, unfortunately, he didn't
understand control (who did at the time?) so his test (like everything
else in the life sciences) was based on the idea that behavior is OUTPUT.
An understandable (but in 1992 a quite unnecessary) misconception.

Best regards

Rick


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Richard S. Marken                   USMail: 10459 Holman Ave
The Aerospace Corporation                   Los Angeles, CA 90024
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