From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!uunet!trwacs!erwin Mon May 25 14:07:34 EDT 1992
Article 5885 of comp.ai.philosophy:
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>From: erwin@trwacs.fp.trw.com (Harry Erwin)
Newsgroups: comp.ai.philosophy
Subject: Re: Grounding: Real vs. Virtual (formerly "on meaning")
Message-ID: <603@trwacs.fp.trw.com>
Date: 24 May 92 22:20:50 GMT
Organization: TRW Systems Division, Fairfax VA
Lines: 56

Keywords: symbol, analog, Turing Test, robotics
Distribution: world
References: <1992May20.191738.18644@mp.cs.niu.edu> <1992May21.173906.22368@psych.toronto.edu> <595@trwacs.fp.trw.com> <1992May22.152511.675@news.media.mit.edu>

minsky@media.mit.edu (Marvin Minsky) writes:

>In article <595@trwacs.fp.trw.com> erwin@trwacs.fp.trw.com (Harry Erwin)
>writes:
>>Held's (1968) article, "Action contingent development of vision in
>>neonatal animals," (Experience and capacity, D. P. Kimble, ed., New York:
>>New York Academy of Sciences) has something to contribute to this
>>argument. Perception involves a motor process and hence motor activity is
>>necessary to organizing perception. This motor activity typical involves
>>the manipulation of "physical objects" and so provides a grounding for
>>experience. Young mammals denied the opportunity to manipulate and move
>>fail to develop cognitively.

>I'd be careful about using this for philosophical argument because it
>is not clear that motor feedback is required for human development --
>at least in "large quantities".  In the LOGO project here, a graduate
>student, Jose Valente, was introduced to a severe CP patient who could
>only grunt and voluntarily move a few muscles.  He was considered
>hopelessly retarded by the institution staff (age 17).  Valente
>coupled him to a turtle geometry system with a head-pointer, and it
>nturned out that he new quite a lot of language and quite a lot of
>intuitive geometry; in a couple of years he had become a good
>programmer, was admitted to Amherst, and got a job in a registrar's
>office in a local university, etc.

>I'm not exactly disagreeing with Harry; only thatdespite Richard
>Held's great experiments -- which included monkeys! --, it seems that
>humans are not quite typical "small mammals" presumably because they
>can construct internal virtual realities and use these for "internal
>premotor feedback."

You're correct. Although cerebral palsy varies in its severity, it seems
to reflect motor cortex damage only, and cognition is normal. (My son, for
instance, who is entering college this fall, has very superior
intelligence.) I've discussed this with Paul Werbos, and the evidence of
CP seems to provide insight into this area. The damage seems to be quite
precisely to the portion of the cortex involved in calculating the
sequence of opposing forces needed to implement a voluntary action. (The
typical poor muscle tone seen in individuals with CP also supports this.)
The remainder of the circuit seems to be undamaged, since, once learned, a
pattern can be replicated: the triggering stimulus from the forebrain
appears to be normal, memory is retained, somatic feedback is present, and
the role of the cerebellum appears to be normal. Therapists exploit this
to overcome the motor cortex damage. Hence, the key elements appear to be
the triggering stimulus and the somatic feedback. I don't know where that
leaves my argument, so I'll beg off for a while to think it out further.

Cheers,
-- 
Harry Erwin
Internet: erwin@trwacs.fp.trw.com



