Newsgroups: bit.listserv.csg-l
Date:         Thu, 27 Aug 1992 14:25:07 EDT
From:         mmt@BEN.DCIEM.DND.CA
Subject: Re: Misc Replies

[Martin Taylor 920827 14:00]
(Rick Marken 920827 10:00)

I'm lost.  I don't understand what it is that Rick doesn't understand so I
can't answer his questions.  Rick seems to be saying that there are no more
sensory degrees of freedom than motor degrees of freedom, and that all
ECSs can always be controlling.  That, at least, is what I think is the case
in the models I have seen simulated or discussed.  But it can't be true,
and I'm sure Rick knows it can't be true, any more than it can be true that
we behave in a strict S-R manner.  So, since I believe Rick to be reasonable,
there must be some intent behind his questions that totally escapes me.

=============quotes follow.

 All I'm asking for is some data that would motivate the need
to revise the existing model (which handles many simple cases of control). I
would suggest a very simple experiment; just so I could get the idea of what
you are talking about. tI scould probably just be a simple extension of a
multidimensional tracking task (which we know the model can handle). Just
create a simple change in the experiment that produces consistent results that
pose a problem for the existing model.

>There really isn't any experimental demonstration that I can think of,
>because

If you really can't do an experiment that tests your proposed revision of the
model then I can't see that it's such an important revision; since the model
accounts for the phenomena we've observed so far I can't see revising the
model to help it explain a phenomenon that we will never be able to
observe.

============a sort of response? follows:
Has the model accounted for all the phenomena of human life observed so far?
I thought that I mentioned a couple of phenomena that seem not to be covered
by the N-in N-out model: the flick of the eyes to an unexpected movement,
the turn of the head toward an unexpected noise.  These seem to involve a
K-in N-out model, where K>>N.  This seems crystal clear, and I don't suppose
that's where the problem lies.

All I am doing is simply pointing out a fact that must be true in the real
world (as opposed to the world of constructed models acting in trivial
environments).  It's as much a fact as that disturbances sometimes affect
CEVs that correspond to percepts.  The latter fact leads to PCT in general,
the df discrepancy leads to what I have called "alerting systems" within PCT.

Perhaps there's a misunderstanding about the difference between being able to
observe a phenomenon and being able to do experiments on it.  Rick, is that
where the problem lies?  Astronomers can observe but not experiment.  They
can model their phenomena using the results of experiments done by physicists
and chemists.  My claim was not that there are no observable phenomena
attributable to alerting systems, but that we couldn't undo evolution, and
wouldn't ever find an active living system without them; and if we constructed
a simulation, its construction would be whatever the designer decided.  If it
failed to respond to an alerting condition, the reason would be in the design.

And I did ask if anyone else could think of an experimental situation that
might tease out the mechanisms of alerting (as opposed to its existence).
Maybe there could be experiments in the area of high workload stress, but
they would probably be very complex, and I can't see how they would work.

Finally:
>>I doubt you could ever find a phenomenon that can be described by only
>>one organization.
>
>True. But a collection of observations can usually only be explained just one
>of the models.

When you are comparing the relative merits of a fixed set of models, any
observations can change their relative likelihoods.  But there is always
an infinity of other models standing in the wings awaiting their turn to
be tested.

I have a fundamental proposition about science that I have seen no reason
to change since before my grad school days:

"Whatever your theory, it is either imprecise or wrong."

Martin
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU