<Bill Cunningham 940601.xxxx)
From Rick Marken (940531.1745)
"To arms! To arms! The British are coming."
This is alerting information, (per Martin Taylor 940530.1700).
It does two things. First, requires the recipient to control
for something that was previously unimportant. In so doing, it
reduces the recipient's degrees of freedom with respect to many
things that could be controlled for.
How does it "do" these things? If I heard this information
(rather than read them) would I start controlling for something
Yes. Remember I said my major interest was the basis or bases for
shifting control from one thing to another, the equivalent of
throwing some switches in the standard diagram. Alerting
provides one basis for shifting control, but not necessarily the
mechanism. The mechanism could be something like the pattern
match scheme I showed. The pattern matcher lurks, controlling
nothing until a specific prespecified pattern is matched within
whatever tolerance has been set. Then control is abruptly shifted
to the appropriate reference(s).
Reference for the effector side? Specification for output? Why
would you consider "course of action" templates if you are
taking action in a world that may change substantially while you
are taking the "course of action"?
Perhaps a bad way of putting it, but the central point I wanted
to portray was shifting control for X to control for Y. At the
higher levels and for the problems I have the most interest, the
result of action is usually not immediate and the report of
results is certainly not immediate. So, one sets forth to do
some things that will change a future perception of the world.
That involves use of the imagination loop to predict that the
future perception will agree more closely with what is controlled
for. Once the projected future us satisfactory, the candidate
actions are initiated. For fast moving situations, they are
probably initiated before a projection is complete. It is
entirely possible that the world may change while taking a
"course of action". So what?. What says the "course of action"
must remain fixed?
Where is uncertainty perceived in the model?
What does the perceptual function look like that puts out a
signal proportional to uncertainty (this, for me. is the
crucial question)? How is the perception of uncertainty
affected by the outputs of the system?
I think there are several possibilities. One way would be to
recognize the absence of a match between the incoming set of
perceptions and the extant set of situation templates. That is a
binary proposition that, to use Bill P's terminology, uncertainty
equates to anxiety (940527.1400). The binary proposition is a
bit crude, but it could constitute a basis for shifting control
to the business of reducing anxiety.
The simple comparators could be replaced by what I'll call
Kanerva boxes, the output of which is the Hamming distance
between the perceptual input and the associated template. That
is scalar measure of mismatch, and thus uncertainty. Unmatched
coordinate pairs denote the specific uncertainty that needs
resolution. More to the point, this scheme makes it possible to
identify unmatched coordinate pairs that, if matched, would
resolve ambiguity between candidate templates. Thus, a degree of
anxiety, and about what. Which should lead to actions upon the
environment that cause the perceptions of same to change, which
if appropriate will reduce the anxiety. If inappropriate, the
error remains. So what's new? Behavior still controls
Nothing requires a proportional signal. For openers, the system
needn't be linear. For the time scale I am most interested in,
it would be unreasonably inefficient and ineffective to control
continuously for the same things. Thus: a need for some basis on
which to shift control, and what becomes essentially a sampled
data system. Both require tools to deal with discontinuities.
Bill Powers (940531.1800 MDT)
The most interesting aspect of your Paul Revere example is that
nowhere in it is it necessary to speak of controlling for low
uncertainty. What Revere is perceiving is, as you say, 0
lights, 1 light, or 2 lights. This is translated into
higher-level verbal perceptions: no attack, attack by land, or
attack by sea.
Thereby resolving ambiguity about the possible states of the
At one time or another, I've considered most of the potential
complications of the problem you raised. Nobody said it was a
noiseless communication channel. William Dawes provided a
redundant channel by sneaking past the guards on Boston Neck and
performing essentially the same mission. That should take care
of the possible noise.
Controlling for reduction of uncertainty, Revere positions
himself to observe whether 0 or 1 or 2 lights are displayed.
"Controlling for uncertainty" is your way of CHARACTERIZING his
attitude toward what is going on. Even if there is some
uncertainty in Revere, that is not what he is controlling for --
even if the uncertainty is reduced.
That is exactly my way of characterizing Revere's attitude. At
some highest level, he was probably controlling for some noble
patriotic act and perhaps a mention in dispatches by Longfellow.
And to do that he had to deliver the appropriate message, which
was uncertain until the moment received (perceived and decoded,
if you like).
And so to to deliver the appropriate message, he had to control
for reduction of the uncertainty across a narrow range of
possibilities. So he parked himself in a position to observe Old
North Church. He did not go to Fenway Park to watch the last Red
Sox World Series winners Had it been foggy, he would have
would not have resolved his uncertainty and we would be reciting
poetry about Dawes, or even the revolution of 18xx.
What you are doing is like saying that a person who buys a new
Buick is controlling for raising the percentage of Buick owners
in his neighborhood.
False simile. What I am doing is like saying that if a person
controls for raising the percentage of Buick owners in his
neighborhood, buying one will achieve what is said to be desired.
The only way in which we could say that a person is
controlling for low uncertainty would be to show that that
person is _perceiving_ uncertainty, which would require that
person first to perceive the size of the decision space and all
the associated probabilities, and second to perform the
In your post of 940527.1400, you suggest "anxiety" as the thing
controlled for. That might be a better term, or perhaps the
connection we seek. But if "anxiety" is okay for you, please
tell me how you are going to show that as a controlled variable.
Only then would there be a perceptual signal representing
uncertainty, and only if such a signal existed could we say that
there is or may be a control system controlling uncertainty
relative to a reference level of zero.
You are changing the game, perhaps prematurely. The original
question was whether such a system could exist, not whether one
can prove a particular system does control for reduced
uncertainty. Proof of the latter would certainly constitute
proof of the former. Absence of proof of the latter does not
disprove the former.
I do not in any way doubt your statements about decision spaces,
the implied world of probabilities, or the process of making
decisions based on probabilistic knowledge (like triage). It is
possible to estimate decision spaces, to assign realistic
probabilities to the alternatives, to calculate the best course
of action based on the outcome of the calculations, and to
produce the decided-upon action. But I think that the only
people who behave this way are those who have been taught to
behave this way or have invented it for themselves -- who have
learned to see the world in terms of probabilities and disjoint
alternatives, who think in terms of making either-or decisions,
and who believe that once the best course of action has been
selected, it should simply be carried out. It is quite possible
to set up guidelines, to provide computing services to do the
necessary calculations for people who don't know how to do them
themselves, and to teach people how to use the results in
deciding on preselected courses of action.
You may be quite right about a select fraction of the population,
although I'd modify "only" to "most", just to avoid an unprovable
absolute. But this sort of person seems to gravitate into
positions where that behavior is appropriate (doctor, lawyer,
Indian chief). But these folks are independent control systems,
too. And so, we (or at least some of us) seek a model that deals
with both aspects of their behavior.
Where I know you are dead wrong (by observing counter-examples)
is the universal assertions that (a) "who believe that once the
best course of action has been selected, it should simply be
carried out;" and (b) "It is quite possible to set up
guidelines.......and teach people how to use the results..."
There are unquestionably people who believe that life is simply a
matter of carrying out a course of action initially judged to be
"best". This is especially true for those engaged in fast moving
competition where bold execution of ANY plan is more likely to
succeed than the best plan with tentative execution. It is most
typical of American football, which either influences or mirrors
our society, depending on viewpoint. These folks tend to be
quite successful for single, local, events. Sometimes their self
confidence/arrogance is unsufferable. But those who are truly
successful are able to adapt to circumstances as they unfold.
They view themselves as performing in a control loop, albeit
described differently. One of their major concerns is reducing
loop delays to make them more responsive to external
disturbances, a major part of which is identifying and reducing
uncertainties with respect to their decision problem. Their
sports anologies are becoming more soccer-oriented.
As for setting up guidelines, using machines and teaching people
to use them--the history of failure is abysmal. Mostly, in fact,
due to lack of understanding of how humans are somehow capable of
dealing with information (in the popular sense). Machines could
certainly help, but it is now fairly well recognized by the _user
community_ that understanding of how humans deal with uncertainty
So it could be that in your work with decision-making under
adverse circumstances, you are working out methods and
principles that can be valuable. But you are INVENTING and
DESIGNING these methods and principles; they are not an inborn
aspect of the brain. They are products of a brain.
Perhaps. I'm not insulted by that accusation. The principles, I
think, would belong to a process model, whereas the methods would
be learnable tools for exploiting the model. But contriving an
adequate process model would be a great leap forward, even if it
is a model of what a few select people have learned to do with
their brain. Given the power of PCT, how can it contribute to a
solution? In particular, does PCT explain how control is
shifted from one variable to another, and on what basis?
BTW, PCT is a model. A very good model, but a model nonetheless.
Kanerva's algorithm is based on neurophysiology and a model of
pattern matching in the brain. Models are products of brains.
Best, Bill C.
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