[From Rick Marken (2000.10.14.1840)]
Bruce Gregory (2000.1013.1423)--
In my understanding you can always construct a tentative
HPCT model to explain why and how you are controlling a
particular perception. That model is not always easy to test,
however.
I think it's no easier to construct a tentative model than it
is to test one. My tentative model of a baseball outfielder was
not particularly easy to construct; I think the same was true of
Bill's model of a person pointing at a moving target, Wolfgang
Zocher's model of eye movement behavior or Richard Kennaway's
model of a six legged walking bug.
There is quite a lot involved in modeling including 1) a detailed
quantitative description of the behavior to be produced by the
model 2) a detailed quantitative model of the environment in
which the model behaves 3) guesses about the variables to be
controlled by the model 4) guesses about the hierarchical relationships
between the systems controlling these variables
5) estimates of system parameters (gain and time constants) that
produce stable behavior that is also realistic, etc.
There are also other, more "artistic" decisions involved in
modeling including 1) the level of structural and functional
fidelity that is sufficient (for example, should the perceptual
functions work as they are thought to work in the brain or are
mathematical functions OK) 2) the aspects of the behavior of
the model (other than those noted in 1) above) that should be
considered relevant to the success of the model (for example,
should the path length allowed at each point by the E. coli model
match the path length allowed at those same points by subjects
or is it sufficient that the model paths always eventually end
up at the target, as is the case with the subject). All in all,
I would rate the task of building a working model of behavior
as being just as difficult as the task of testing the model.
Am I really typing this message in order to convince you
that I understand HPCT? That certainly is one model.
I would not call this a model. It's more like a description
of what you might be doing, a description that is informed by
an understanding of the general HPCT model. A real model would
have to be "built", either as a computer program, an electrical/
mechanical analog or a set of mathematical equations. To model
this behavior you would first have to give a reasonably quantitative
description of the behavior that the model is going to have to
produce; perhaps the frequency with which certain kinds of messages
are posted to the net. Then you would have to develop a model
of how your actions as well as other independent environmental
events (disturbances) affect variables in the environment; this
would be a model of the environmental connection between actions
(like typed messages) and their results in the environment. Then
you woudl have to guess at the variables that might be kept under
control by actions like typing messages; and so on. Obviously,
modeling involves a _lot_ more than constructing a one sentence
explanation of behavior.
I don't think modeling is really the way PCT is used on an everyday
basis anyway. Obviously, people are not going to sit down and create
a computer model of every behavior they find interesting. I think,
therefore, that the main everyday "use" of the HPCT model will be as
an interpretive framework rather than as a model per se. For example,
the HPCT framework made it possible for you to look at typing e-mail
messages as a lower level goal aimed at achieving the higher level
goal of "convincing people that you that you understand HPCT". The
HPCT framework also suggests that goals are states of one's own
_perceptions_; so, so your goal is not really to "convince
people that you understand HPCT"; you can't perceive whether or
not people are really convinced. What you can perceive is what
people say and do. So your goal is more like having a perception
of people saying things like "I am convinced that you understand
HPCT".
HPCT also helps us see control when it goes wrong; when, for
example, you try to control for eating ice cream and typing
at the same time. Obviously, you can't shovel ice cream in and
type with two hands simultaneously. A person who tries will
suffer conflict and the conflict will be seen as unsuccessful
control of one or _both_ perceptions. Conflicts like this
are usually solved pretty quickly; the person sees that it is
possible to type a little, then eat a little, then type a little
more, then eat a little more, ...etc.
I think we learn how the HPCT model works by studying working
implementations of the model, like the little man, fielder,
bug and eye movement control system. Once we know how the model
works, we can use the model as a framework for understanding
the everyday behavior we see.
Best
Rick
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Richard S. Marken Phone or Fax: 310 474-0313
Life Learning Associates e-mail: marken@mindreadings.com
mindreadings.com