[From Rick Marken (2010.03.24.0945)]
Bruce Gregory (2010.03.23.0955 EDT)--
BG: I am beginning to appreciate Bill's claim that causality is not a useful scientific
concept. Let's assume your description is correct. Your diagram does not stand by
itself. Rather it is embedded in a series of loops.
RM: Yes. And this loop is sometimes shown in diagrams of information
processing systems but it's always interpreted sequentially, as a
series of steps. For example, in chess the sequence would be: board
position --> memory --> move selection --> move --> new board position
--> memory etc. Basically a snazzy S-R chain. What they don't get is
the fact that all this is happening at the same time (integrating over
a sufficient time interval) in a negative feedback loop. And when you
have a system (chess player) -- environment (chess board/opponent)
relationship that is organized as a negative feedback loop then the
system (the chess player) is a control system controlling various
perceptual aspects of the environment (board). This is what Simon
seems to have tacitly understood when he developed his chess playing
programs because these programs were organized as control systems. The
chess program made moves in order to achieve goals and subgoals
specified by the program itself.
Simon's chess playing program was built simply to see if one could
build a machine that could play chess; it was a computer science
experiment. The field of cognitive science emerged when it was
realized that these computer programs could be considered a theory of
how people think. Unfortunately, this all happened when the only way
psychologists knew how to test theories of mind was using an
input-output model; the causal model of conventional experimental
psychology. Thus we have the Chase and Simon experiment, which could
only test an input-output model of chess playing: board position
(input) evokes position-move memories (output). So the conclusion of
that experiment was that chess playing is a (sequential) input-output
process: board position --> memory --> move --> new board position -->
etc.
If Simon had understood how control theory applies to behavior -- that
is, if he knew PCT (which he was unlikely to have had much contact
with back then) he would have known that a goal was a reference for an
perception and that the way to test to see whether expert chess
players actually try to achieve the same goals as his chess program is
to test for controlled variables. This would be quite a different
approach to the study of chess playing (and problem solving in
general) than the one dictated by conventional experimental
methodology.
So the essence of the problem (which is why I brought up the Chase and
Simon paper in the first place) is that the study of thinking using
conventional methodology has unfortunate consequences. There are
actually two unfortunate consequences. The first (which I already
mentioned) is that conventional methods virtually force the conclusion
that cognitive behavior is an input-output process since the research
is based on an open loop input-output model. The second is that
conventional methods ignore the possibility that the observed behavior
is organized around control of various perceptual variables:
controlled variables.
Controlled variables are central to the study of living control
systems. The search for controlled variables (using "the test") is
what distinguishes the methods used to study closed-loop control
(i.e., living) systems from conventional methods, which are
appropriate for the study of open loop (i.e., non-living) systems.
Indeed, those with a vested interest in conventional methodology react
to the term "controlled variables" in the same way that a vampire
responds to the presence of a crucifix. The possibility that behavior
is organized around the control of perceptual variables, and that the
input-output relationships that are measured in conventional
experiments are simply the observed efforts by the system to protect
(via output) these controlled variables from disturbance (the apparent
"input"), is the truly revolutionary contribution of PCT to the study
of living systems (in my opinion).
I suspect that your objection is based on the fact that selecting the next move
does not appear to be closed loop.
Not at all. My objection is based on the fact that Chase and Simon
describe chess playing as an open loop input-output process rather
than as a control process. The most obvious evidence of this is that
they don't view chess playing in terms of controlled variables.
However, a test for the controlled variable might show otherwise.
Of course, that's what you would find in fact; but it's not part of
their theory. Of course the placement of the pieces is controlled. But
more important, higher level perceptual aspects of the board are
surely being controlled, such as "control of center","threats to the
queen", etc. These are things that Simon might have tested for if he
had understood control theory.
Actually, there was a study done in about 1980, on solving water jar
problems, that did do something like a test for a controlled variable
when solving these problems. It was a really nifty paper -- by Atwood
and Polson, reported in _Cognitive Psychology_, I believe. What they
found was evidence that one of the variables controlled for when
solving such problems was a perception of the current state of the
problem being similar to the goal state; I think they called it a
"means-ends" strategy. Anyway, what they found is that most
individuals do control for this perception and it's what makes problem
solution difficult. The solution of the problem requires moving the
contents of the jars, at one point in the problem, to a state that
looks _less_ like the goal state. I guess I should have done some
follow up on that research, but other things took priority. But maybe
now is the time, since there seems to be some skepticism about the
relevance of PCT to cognitive behaviors like problem solving.
If you attempt to prevent me from making the move I have
selected, say by grabbing my arm, I will resist the disturbance.
Yes, grabbing you arm is a disturbance to your control of piece placement.
Your move may disturb my plan.
I would say that my move is a disturbance to a perception of the board
that you are controlling for. It is (hopefully, from my point of view)
a disturbance to your control of one perception you are surely
controlling for: the perception of me being checkmated.
As a result, I will adopt a new plan because I intend to win or to force a draw.
Your moves act (like the movements of the mouse in a tracking task) to
compensate for the disturbance my move creates to whatever are the
perceived states of the board you are controlling for. It's those
perceived states that players want to keep the board in that should
have been the main main focus of Simon's study of human chess players.
> As I recall, the history of chess playing programs started
withmhose efforts, which
may seem to embody closed-loops in a more obvious way, did not prove terribly
successful. If PCT can leader to a better approach to programming a computer to
play chess, I suspect it will be recognized.
PCT is aimed at understanding how living systems control and it's
success will be measured by how well it does that. The application of
PCT to chess playing would be aimed at understanding how human chess
players play chess. Since machines can now regularly beat humans at
chess (using exhaustive search algorithms that would be impossible for
a human) it seems unlikely that PCT would be able come up with a
better approach to playing chess than what is already being
implemented in computer programs.
Best
Rick
···
--
Richard S. Marken PhD
rsmarken@gmail.com
www.mindreadings.com