"Strength" of neural signals (was Re: Query re: Intro to Modern Psychology)

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[From John Anderson (970105.2210)]

[From Bill Powers (970103.2110 MST)]

Bruce Gregory (970103.1715 EST)--

>One page 9 of _Introduction to Modern Psychology: The
>Control Theory View_, the statement is made, "An organism
>may have _reference signals_ of different strengths in its various
>control systems, of course, and there thus will be priorities
>observable in its actions." The notion of the strengths of
>reference signals is unfamiliar to me. Is reference being made
>to the gain of the associated feedback loops, or is something else
>going on that I am missing?

The reference _should_ have been to loop gain, I suppose. The technical
stuff in that book is a little rough in places.

But changing loop gain doesn�t have the same effect as changing the
strength of a reference signal, does it? It�s my understanding that
changing the loop gain only affects how quickly and effectively a
disturbance is countered. A control loop with negatively infinite gain
will maintain the controlled perception exactly at the reference level
(see the discussion on pages 50-51 of IMP). A lower (less negative) loop
gain would hold the perception less exactly to the reference level, but
the reference level and the controlled perception would still have the
same �strength�. A _stronger_ reference signal, on the other hand,
would require the perception to become �stronger�, whatever that means,
with the loop gain still only affecting how closely the controlled
perception matched the reference. Am I right?

This leads me to wonder (with Bruce Gregory) what exactly is meant by
the �strength� of a reference (or perceptual, or error) signal?



John E. Anderson