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Date:         Fri, 4 Sep 1992 11:23:37 -0600
From:         "William T. Powers" <POWERS_W%FLC@VAXF.COLORADO.EDU>
Subject:      Concepts & models; Busses

[From Bill Powers (920904.1130)]

Martin Taylor (920903.1900)]

RE: concepts and models

>I don't have or expect to have a specific model of alerting systems.
I >can think of many.  But the situation is like that of PCT itself.
The >basic proposition of PCT, that "all (purposeful) behaviour is the
>control of perception" is incontrovertible.  There are many models
that >might instantiate it.  So with the alerting systems.  Given the
basic >proposition of PCT, their existence in an organism supplied
with more >sensory than motor degrees of freedom is incontrovertible.
There are >many models for how they might work.

It's not self-evident that left-over perceptions or control systems
must have the function of "alerting." I don't dispute that there will
be perceptions and systems not in use, because of the df problem.

The "concept" of control that I was talking about was the concept that
behavior controls perception. This concept is seen as fitting
experience: that is, any behavior you happen to notice turns out to be
a perception, on closer consideration. Cut off the relevant perception
and you can't do the behavior, particularly in the presence of
disturbances.

The model is the CT model. It shows the kind of organization that's
required to create the effect observed. With due regard to alternative
but equivalent forms of the same model, it's the only known kind of
system that can produce this sort of phenomenon. There's no
alternative that I know of.

In the CT diagram, every block and every arrow is assigned a specific
function. By instantiating these functions it's possible to construct
a working model of a control system. Even in cases where we can't yet
instantiate the functions, we can see that if we could, or if we could
fake it, we'd have a runnable model.

This is what I'm after regarding your "alerting systems." You show
them as control systems not connected to lower systems, but sending
arrows over to the active control systems. What is the meaning of
these connections? What KIND of effect are they supposed to be having
on the target system, and what is there about their origins and
destinations that makes this effect plausible? Are you including
enough machinery in this model, even in block form, to enable it to do
the things you say it should do?
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--
>As for "controlling for variability," I was more musing than
proposing, >but if you want a proposal, you mentioned a while back
that if you had >two one-way control systems back-to-back to make a
two-way one, and if >they had the right (square-law?) control
function, then the pair could >be controlled both for gain and for
reference level.

I can see that the variability of the perceptual signal relative to
the reference signal would be changed by changing the loop gain,
loosening or tightening control. But that is AFFECTING variability,
not CONTROLLING FOR variability. In order to control for variability,
the system that is varying the common-mode reference signal must
perceive something about the lower system that constitutes its
variability. What would that be?
----------------------------------------------------------------------
-
Avery Andrews (920904.0950) --

>Re busses:  fine.  But as far as I can see, Chapman's architecture is
>consistent with this - as long as you have a finite system of
>categories sent along the bus, you can have a single wire coming off
>for each one.

But then for each category wire, you need a category-perceiver at the
lower level. This just moves the problem down a level. Each category-
perceiver has to receive all the elements that could be categorized,
and respond to the one category it is designed to detect. There could
still be an infinity of categories, with only those actually perceived
having any effect in the system.

>PS did Harry Erwin really send something to CSGNet?  I posted
something >of his yesterday, but I also lost a whole swag of unread
messages 2 >days ago, so might well have missed a posting by him.

I thought the post was from him. Sorry.
----------------------------------------------------------------------
-
Best,

Bill P.
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU