Newsgroups: bit.listserv.csg-l
Date:         Mon, 23 Nov 1992 15:28:46 EST
From:         mmt@BEN.DCIEM.DND.CA
Subject: Re: privileged points of view; language experiments

[Martin Taylor 921123 11:40]
(Bill Powers 921122.2000)

Continuing my interrupted posting of 921122.1340, to which Bill has commented:

>The analyst is a human perceiver. In my own mind, I do not allow
>privileged points of view in HPCT: whatever any human observer can do
>must, at least in principle, be explained by the same model. So if the
>analyst sees meaning or pattern in the vector, the analyst's perceptions
>are combining the individual elements of the vector and reporting a
>unitary perception, a scalar perception, in the manner I proposed.
>...
> There is no place to stand from which
>to see what the pattern "really" is. The same model must apply to the
>observed and observing human systems. It must also apply to a human
>being looking at a model, too.
>
>The computations that produce the individual elements of the vector
>might well interact, so that the elements are not independent. That
>subject has to do with the internal design of one level in the
>hierarchy; what the next level makes of the vector is a different
>subject.

To all of which, I naturally say, "of course."  But I suppose there might
be listeners to whom it is not obvious, and therefore it is a worthwhile
expansion of something I thought not worth mentioning.
---------------
Now let's continue with where I think one of us is missing the other's point,
and, not having a priveleged point of view, I can't tell whether it is you
or me.  So I perhaps have to spell out more than I think should be necessary.

(Bill Powers 921120.1300)

>You replying to Rick:
>
>>>The question in my mind is: why should it be true that
>>>at some point, some resource (a cell or cell assembly) is going
>>>to have to represent the state of the distributed representation
>>>to someone other than the person watching the model -- ie. there
>>>will have to be a perceptual signal that represents the state
>>>of the distributed representation...
>
>The "someone else" is a higher level system. This discussion is
>making me go back through some old musty trains of thought that
>eventually led to HPCT.

The way I put it may have been misleading.

On reflecting over posts by you and Rick, I think there are three separable
reasons for considering these complex percepts, even while recognizing
that, in themselves, they have no reality for the perceiver:

(1) as a label that we as analysts may use as a shorthand to communicate
amongst ourselves about groups of things that may be seen to be happening
together (in us, the patterns are the perceptual input functions for scalar
perceptual signals, but we are talking about complex things happening outside
of us).

(2) to represent a subset of the different perceptual signals being controlled
at one level, many or most of which may be inputs to several different
perceptual functions at the next higher level, and that therefore tend to
work together as a modular group (even if the modules do tend to overlap).

(3) as a base on which higher-level ECSs can develop by whatever means of
reorganization creates and effectively links new ECSs (from a bottom-up
point of view, this is a kind of non-linear principal components analysis,
but executed, we believe, by random-walk processes rather than algorithmically).

>The computations that produce the individual elements of the vector
>might well interact, so that the elements are not independent. That
>subject has to do with the internal design of one level in the
>hierarchy; what the next level makes of the vector is a different
>subject.

The next level probably makes many things of the vector, but an outside
analyst would say that those things were of a kind different from the elements
of the vector, or from the vector itself.  Internally, of course, they
aren't--we use the simplifying concept of "neural current" or "neural
voltage" to signify what carries the signals, and all of them are of the
same kind.  What is of different kind is the CEV represented in the controlled
signal.  In a structured perceptual signal, there are many CEVs, and thus
many degrees of freedom (or perhaps I should put it the other way round).

Let us assume that all the simple perceptual signals in the complex are
under good control--the errors are all close to zero.  But the world provides
disturbances. and those errors (momentarily) deviate from zero.  If (as an
outside godlike observer might see) two or more of these transient errors
tend more often than not to be in the same direction and in the same ratio,
it might often be more efficient for the organism to have an ECS that directly
controlled the sum, perhaps as a substitute for the individual ones, perhaps
as a higher-level ECS that used the individual ones as input.  This is one
version of "leaning on the world."  The correlations among the perceptual
signals in a structured percept would be due not to the structure of the
percept, but to the disturbances generated by the world.  If one ECS can
control against a substantial part of the disturbances that actually occur,
it is presumably efficient that such an ECS would be developed through
reorganization.

We have argued (actually Bill pointed out) that reorganization tends to
drive ECSs into controlling nearly orthogonal perceptual input functions,
but we also know that there are far too many sensory degrees of freedom
for this to happen overall.  In the context of this posting, what this
amounts to is a suggestion that any higher-level ECSs that take the signals
of a structured percept as inputs would tend to develop into a principal
components representation of the structured percept; they would tend to
maximize the information transfer while minimizing resource usage.

When I talk about a "belief" as a structured percept, I am taking account of
the multidiemsionality of the perceptual structure.  Many parallel perceptual
signals may be components of a "belief," even if there is no actual control
of the belief as such--no single perceptual input function to which it
corresponds.  There is only control of the multiplicity of scalar perceptual
signals, all of whose related error signals are to be brought near zero.
It is not necessarily satisfactory for any single function of those signals
to be brought to a reference value, though it could be satisfactory for
several orthogonal functions of those signals simultaneously to be brought
to their several reference values.  But then we would be talking about a
higher-level Structured Control System.

Bill, I realize you are getting bored with "abstract neural networks."  Is
this the kind of thing you mean?  I hope not.

Martin
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