[From Dag Forssell (930920 1840) Rick Marken (930919.2100)]
Rick, thanks for your post. This late in the day, the technical
details have progressed further, but I wish to answer anyway.
To me, you are one of the few de facto vice gurus of PCT. You do
not have to be any more infallible than Bill, (he is not, as you
have noted), or even close, but I expect you to apply PCT at all
times and be extra careful to qualify your remarks when you are
uncertain, and even when you are not. If I did not have a high
reference level for PCT guru-ness on your behalf, I would not have
reacted, would I.
ยทยทยท
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Now getting technical:
In manual control the input to the control system is error
(r-p) where r and p (and e) are considered to be variables in the
environment.
I am not familiar with "manual control." Could you enlighten me?
Whom are you quoting? What is the relevance to PCT? Are you
talking about control engineering?
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I am aware of the behavioral illusion. I have always thought that
the illusion is to think that there is a direct causal
relationship between input p and output o (ignoring r).
Sorry, I misstated this. Had read too much about p and r-p and o
when I wrote this. It is the disturbance and o, of course, as Bill
has already pointed out today. The illusion is the apparent causal
relationship between the two ends of the rubber band, the
disturbance end and the action end, ignoring what the acting person
wants. See. I would have been OK if only I had expressed myself in
the trusty rubber band language.
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If by output you mean the momentary muscle contractions and
therefore hand acceleration, I think Michael's and my notion of
a direct causal relationship between r-p and o holds very well
indeed.
Agreed. But remember, in my question I asked if what was being
caused were "the outputs that affect p, keeping p near r". The
derivative of o (in the model) is not what keeps p near r; it is
what is caused, but it is the current value of the integral that
is the effective output. The integral is what preserves the
effects of all variables around the loop -- and makes it so that
the derivative that is "caused" at any instant happens to be the
"right" one -- ie. the one that has the effect on p which, in the
context of the current environmental circumstance, moves p toward
r.
Boy, describing what we are discussing in plain english ain't easy,
is it. The Fogg index gets sky high. I am comfortable (and
correct?) to paraphrase what you are saying in terms of the Marken
spread sheet. In the first iteration, the output is a direct
function of the error e = r-p. (That's the momentary muscle
contraction part). But it is the accumulated effects of 100
iterations with continuously changing variables all around the
loop, that make sure that p~r, through the environment. (That's the
integration part).
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I think most people would intuitively think that their output is
their muscle contraction -- the way they try to move the hand.
I think the output that matters is the one that influences the
variable under control.
You are not disagreeing with me. It just looks that way. You are
making your point about integration again, right?
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Question ideas; love people.
Yes indeed. On this net we respect each other, and especially
newcomers, as autonomous living control systems.
I love you too, Dag