[From Dag Forssell (970506 11.10)
Last month, I posted a pointer to INTROCSG.NET suggested by Gary
Cziko intsead of the file itself. The vote came back one in favor,
none against. The Ayes have it. However, I will post the entire
file when I update it. That way Gary can pick up the updated file
for the sever.
The update is publication info for the following reference,
supplied by Tom when I inquired.
W. Thomas Bourbon (1995). Chapter 8: Perceptual Control Theory.
In Herbert L. Roitblat & Jean-Arcady Meyer, Eds.: Comparative
Approaches to Cognitive Science. Cambridge, Mass: A Bradford Book,
The MIT Press, pages 151-172.
Chapter surveys applications of PCT modeling by Bill Powers and
Greg Williams (pointing, from the ARM/LITTLE MAN program); by
Rick Marken and Bill Powers (movement "up a gradient" by E.
coli), by Bill Powers, Clark Mcphail and Chuck Tucker (social
movement and static formations, from the GATHERINGS program),
and by Bourbon (tracking). The PCT model is contrasted with some
of the mainstream models and theories presented at the workshop.
Tom also remarked:
By the way, Tim Carey (an Australian educator enthused about PCT)
told me this was the first publication about PCT that helped him
begin to understand the technical, quantitative side of the theory.
This file is posted every month to CSGnet.
INTRODUCTION TO PERCEPTUAL CONTROL THEORY (PCT)
THE CONTROL SYSTEMS GROUP (CSG)
AND THE CONTROL SYSTEMS GROUP NETWORK (CSGnet)
Prepared by Dag Forssell with Gary Cziko
Updated May 6, 1997
This is an introduction to Perceptual Control Theory (PCT), and
the discussion group CSGnet. CSGnet is listed on Usenet as the
newsgroup "bit.sci.purposive-behavior." This introduction is
posted at the beginning of each month for newcomers to CSGnet and
the newsgroup.
A complementary "PCT Introduction and Resource Guide" is available
from the WWW server shown below (Resource.pct). It features the
original book jacket for Bill Powers' seminal 1973 book _Behavior:
The Control of Perception_; two short essays: _An essay on the
obvious_ and _Things I'd like to say if they wouldn't think I am a
nut_, which deal with the requirements for and consequences of
applying physical science to the field of psychology; the foreword
for _Living Control Systems II_ by Tom Bourbon and more; plus more
detailed descriptions of PCT books, videos, articles, sources,
etc.
Contents:
Introductions to Perceptual Control Theory
The Evolution of the Control Paradigm
Demonstrating the Phenomenon of Control
The Purpose of CSGnet
CSGnet Participants
Asking Questions
Post Format
The Control Systems Group
Accessing and Subscribing to CSGnet
World-Wide Web
On-line documents
References
INTRODUCTIONS TO PERCEPTUAL CONTROL THEORY
STANDING AT THE CROSSROADS
Distributed at the Control Systems Group Meeting,
August 15-19,1990, at Indiana, Pennsylvania.
By William T. Powers.
[Comments by Dag Forssell, Jan 1, 1997]
I'd like to try today to give you the sense that psychology is
standing at a crossroads -- and not only psychology, but all the
sciences of life. We are about to experience the advent of
something for which many people have searched, an organizing
scheme that pulls together all the disparate schools of thought,
specializations, movements, and evanescent fads that make up
various fragmented branches of the life sciences.
The organizing scheme is called "Perceptual* Control Theory."
This theory explains a phenomenon, as theories are supposed to
do. The phenomenon in question is called control. Everyone has
heard this word, and most people have occasion to use it from
time to time, but in science it has become part of the
metalanguage rather than designating a subject of study. A
scientist does a control experiment, or demonstrates how
manipulation of stimuli and rewards can control an animal's
movements, or advocates a proper diet to control cholesterol
level or competes for control of a department. This word is used
as part of a background of ordinary language, but it has not
been part of the technical language of the life sciences.
[* The word Perceptual was added at a later conference to
distinguish Bill Power's creation from competing, non-
functional interpretations by other authors. This term is
technically more precise, since all control systems actually
control their perceptions, not their outputs.]
The reason is quite simple: nobody in or out of science
understood the process of control until about the beginning of
World War 2. By understanding the process, I mean being able to
define it, characterize it, measure its parameters, predict how
it will proceed, and recognize it in a real system. This doesn't
mean that control was impossible to accomplish before World War
2: after all, most people accomplish digestion without
understanding any biochemistry. But control is as natural a
process as digestion, and like digestion can be understood in a
scientific way only by studying it and learning how it works.
World War 2 started only about 50 years ago. Perhaps you can see
why this fact implies some problems with studying control as a
natural process. If control is a natural process, it was
occurring in 1840, 1740, 1640, and so on back to the primordial
ooze. In 1940, the sciences of life were already something like
300 years old (and their prehistory was far older than that). If
nobody understood control until 1940, it's clear that these
sciences went through a major part of their development without
taking it into account. The next question is obvious: how did
they explain the phenomena that arise from processes of control?
Many of the puzzles and controversies that occupied early
researchers could have been resolved if scientists had realized
that they were dealing with control processes. Purpose could
have been studied scientifically instead of merely
theologically. We can see now that all these early researchers,
not recognizing a control process when they saw one, were
drastically misled by some side-effects of control. The
principal side-effect that deceived them resulted from the way
control systems act in the presence of disturbances of the
variables they control. When a disturbance occurs, a control
system acts automatically to oppose the incipient change in the
controlled variable. But if this opposition is not recognized
(it's not always obvious), the observer will inevitably be led
to see the cause of the disturbance as a stimulus and the action
opposing its effects as a response to the stimulus. Furthermore,
this opposition results in stabilizing some aspect of the
environment or organism- environment relationship. That
stabilization conceals the role of the stabilized variable in
behavior; the better the control, the lower will be the
correlation between the controlled variable and the actions that
stabilize it. The variable under control is the one that is
actually being sensed, but the logic of control makes it seem
that the disturbance is the sensory stimulus.
Donald T. Campbell [Late Professor of Psychology, Lehigh
University] has proposed a "fish-scale" metaphor of scientific
progress. Each worker constructs just one small scale that
overlaps those already laid down by others. Eventually the whole
fish will be covered completely. But what if the fish is a red
herring? Then all these patient workers will devote their lives
to covering the wrong fish. The converse of the fish-scale
metaphor is that a person who is concentrating on fitting one
little scale to others already laid down is bound to have a very
localized view of the problem. Seeking to extend the
accomplishments of others, a single worker can make what seems
to be progress -- but it is unlikely that a single worker will
discover that something is wrong with the whole design. The
result can easily be the diligent application of fish-scales to
a giraffe.
I submit that something like this has happened in the life
sciences. A fundamental misconception of the nature of behavior,
natural but nevertheless horrendous, has pointed the life
sciences down the wrong trail. Nearly all life scientists,
particularly those who try to achieve objectivity and uniform
methodology, have interpreted behavior as if it were caused by
events outside an organism acting on a mechanism that merely
responds. This hypothesis has become so ingrained that it is
considered to be a basic philosophical principle of science. To
explain behavior, one varies independent variables and records
the ensuing actions; to analyze the data, one assumes a causal
link from independent to dependent variable and calculates a
correlation or computes a transfer function. This leads in turn
to models of behaving systems in which inputs are transformed by
hypothetical processes into motor outputs; those models lead to
explorations of inner processes (as in neurology and
biochemistry) predicated on the assumption that one is looking
for links in an input-output chain. One assumption leads to the
next until a whole structure has been built up, one that governs
our thinking at every level of analysis from the genetic to the
cognitive.
Perceptual control theory, by showing us an alternative way of
understanding this entire structure, therefore threatens the
integrity of practically every bit of knowledge about behavior
that has ever been set down on paper.
This is, of course, a message of the type that leads to a high
mortality among messengers. That is why you are listening to a
person with no reputation to lose and no fame to protect,
instead of a Nobel Prize winner. In an utterly predictable way,
scientists have for the last 50 years gone to great lengths to
avoid learning control theory or else to assimilate it into the
existing picture of behavior. Failing that, they have simply
declared it irrelevant to their own fields, with the result that
the authoritative literature of perceptual control theory is
almost completely insulated from the mainstream. It appears in
publications like proceedings of the Institute of Electrical
Engineers division on Man, Machines, and Cybernetics, or in
human factors and manual control publications, or in Xeroxed
papers passed from hand to hand. There is a scattered literature
on perceptual control theory in the life sciences, but nothing
on this subject gets past the referees into a standard journal
without first having its teeth pulled.
Despite all the defenses, the concepts of perceptual control
theory are spreading. When our descendants look back on the
latter half of the 20th Century, they will probably be amazed
at the speed with which perceptual control theory became
accepted: 50 years in the course of a science is nothing. We
control theorists have nothing to complain about. Our greatest
successes have come not through pounding at locked doors, but
through continuing to explore the meaning of this new approach
and learning how to apply it in many different disciplines. If
we do our job correctly, acceptance will take care of itself.
That job is not something one can toss off overnight, nor can it
be done by just a handful of people. We are coming to a time of
rigorous re-evaluation of all that is known or presumed to be
known about the nature of organisms. The more people that are
involved in this enormous project, the sooner it will be
accomplished. That is why we are all so glad to welcome our
guests at this session: after the party, you will be invited to
help do the dishes.
There has been progress in understanding how organisms work, the
wrong model notwithstanding. Biochemical reactions are not going
to change because of perceptual control theory. Muscles and
nerves will continue to operate as they are known to operate.
Even at more abstract levels of analysis, many phenomena will
continue to be accepted as valid observations; for example,
phenomena of perception, of memory, of cognition. If competently
observed, these phenomena will still be part of the legacy of
earlier workers. When we pull the stopper on the old theories,
we must keep a strainer over the drain and let only the bath
water out.
Part of the task of reconstructing the sciences of life consists
of separating valid observations of components from invalid
conjectures about how they work together. Consider biochemistry
as an example. Biochemistry is an odd mixture of solid research
and wild leaps of undisciplined imagination. The research
reveals chemical processes taking place in the microstructure of
the body. The wild leaps propose that the chemical reactions
somehow directly produce the behavioral effects with which they
are associated. It's as though a specialist in solid-state
physics were to propose that electrons flowing through wires and
transistors are responsible for the music that comes out of a
radio. While it's true that a shortage of electrons will make
the music faint, and that without the electrons you wouldn't get
any music, the physicist would be laughed out of town for
suggesting that electrons cause music, or that you could fix a
weak radio just by putting some more electrons into it. You
can't understand the role of the electrons without grasping the
principles of organization that make the radio different from a
radio kit.
In the same way, if shortages or excesses of chemicals like
enzymes and neurotransmitters are found to be associated with
functional and behavioral disorders, all we then know is that
these substances play some role in the operation of the whole
system that creates organized behavior. If there's a shortage of
some chemical substance, then some other system has reduced its
production of that substance, and some other system still has
decreased its effect on the driving system, and so on in chains
and causal loops. Nothing in a system as complex as the human
body happens in isolation. If biochemistry is to have anything
to say about the organism at any higher level, biochemists are
going to have to study whole systems, not isolated reactions. We
need a functional theory to supplement the microscopic laws of
chemistry.
There are workers in biochemistry who are investigating feedback
control processes. One significant process involves an
allosteric enzyme that is converted into an active form by the
effect of one substance, and into an inactive form by the effect
of another. When these two substances have the same
concentration, the transition from active to inactive is
balanced; the slightest imbalance of the substances causes a
highly amplified offset toward the active or the inactive form.
In one example, the active form catalyzes a main reaction, and
the product of that reaction in turn enhances the substance that
converts the enzyme to the inactive form -- a closed-loop
relationship. The feedback is negative, because the active form
of enzyme promotes effects that lead to a strong shift toward
the inactive form. This little system very actively and
accurately forces the concentration of the product of the main
reaction to match the concentration of another substance, the
one that biases the enzyme toward the active form. This allows
one chemical system to control the effects that another one is
having on the chemical environment.
A person without some training in recognizing control processes
might easily miss the fact that one chemical concentration is
accurately controlling the product of a different reaction not
directly related to the controlling substance. The effect of
this control system is to create a relationship among
concentrations that is imposed by organization, not simply by
chemical laws. This is the kind of observation that a
reductionist is likely to overlook; reductionism generally means
failing to see the forest for the trees. Even the workers who
described this control system mislabeled what it is doing --
they concluded that this system controls the outflow of the
product, when in fact it controls the concentration and makes it
dependent on a different and chemically-unrelated substance.
To shift through several gears, consider the lines of research
that began with Rosenblatt's perceptron. This device was
conceived as a behavioral system that could be trained to react
to patterns contained in its input information. First this idea
was shown, by something of a hatchet job, to be impractical, and
then it was shown to be practical again if several levels of
training could occur within it (I haven't seen any apologies to
Frank Rosenblatt, who died without vindication). In all its
incarnations, however, the perceptron has been thought of as a
system that learns to "respond correctly" to a stimulus pattern.
From the standpoint of perceptual control theory, however,
organisms do not respond to stimuli but control input variables.
So does that invalidate all that has been learned about
perceptrons? Not at all. Perceptual control-theoretic models
desperately need something like a perceptron to explain how
abstract variables can be perceived. In a perceptual control
model, however, the perceptron is only one component: it
provides a signal that represents an aspect of some external
state of affairs. It's easy to show that behavior can't be
explained simply by converting such a signal into an output
action. But behavior can be based on the difference between the
perceptron's output signal and a reference signal that specifies
the state of the perception that is to be brought about. The
control-system model shows where the functions that are modeled
as perceptrons belong in a model of the whole system.
Shifting gears again: some theorists are trying to model motor
behavior in terms of "motor programs" and "coordinative
structures." In these models, command signals are presumed to be
computed such that when applied to elastic muscles they produce
the movements of a real limb. These models contain some
impressive mathematics, taking into account the linkages of the
limb and the dynamics of movement of the limb masses. But
perceptual control theory says that behavior is not produced by
computing output; it is produced by comparing inputs with
desired inputs, and using the difference to drive output. No
complicated "motor program" computer is needed. Does this mean
that the mathematical analysis by the motor program people is
spurious and ought to be discarded?
Again, not at all. At some point in elaborating the perceptual
control model, we must show how the driving signals actuate
muscles to cause the movements we actually see. This entails
solving all the physical equations for muscle and limb dynamics,
just as the motor programmers have done. If they did their
arithmetic right, it will still be right when we substitute the
perceptual control-system model for the central-computer model.
Both models have to produce the same driving signals. The only
thing that will change is that perceptual control theory will
show how the required driving signals arise naturally from
perception and comparison against reference signals, instead of
being computed blindly from scratch.
Finally, shifting to overdrive, what do we do about Artificial
Intelligence? We take advantage of whatever it really has to
offer, modifying it only where we know it fails to explain
enough. One place where it fails to explain enough is in the way
it deals with action. Basically, it doesn't deal with action. It
starts its analysis with perception of abstract variables in the
form of symbols, constructs models that imitate human symbol-
handling processes as well as possible, and finishes by
generating more strings of symbols that describe actions to be
taken. It says nothing useful about how a description of an
action, in symbols, gets turned into just those muscle tensions
that will in fact produce an action that fits the description.
When devices are built that are run by symbol-processing
computers, the critical transformations that make action out of
symbols are simply put into the device by its builders. Many of
those critical parts turn out to be servomechanisms --
perceptual control systems.
The assimilation of perceptual control theory into the life
sciences will require a lot of this kind of reanalysis. Some old
ideas will have to go, some will stay. This job is best done by
people who are already competent in existing fields. Of course
these also have to be people who can see that there is room for
improvement along lines other than the standard ones.
In the current membership of the Control Systems Group we have
representatives of at least a dozen disciplines of the life
sciences, and a few persons representing some unlikely
occupations such as piano teaching and law. When these people
meet, there is little difficulty in communicating because all of
them have a basic understanding of perceptual control theory.
But communication isn't the only factor that makes these
meetings valuable. The most important lesson comes from seeing
how perceptual control theory applies in someone else's field.
The biggest problem with introducing perceptual control theory
to scientists in conventional disciplines is that each scientist
tends to think only of the scientific problems that are defined
in that one field. The problem in question may involve behavior,
but behavior is generally taken on faith to work the way some
other specialist says it works. In fact most scientists tend to
dismiss details involving other fields, assuming (often quite
wrongly) that somebody else understands them well enough. We
therefore find some very detailed biochemistry or neurology or
personality- testing, all done competently, being used to
explain behavioral phenomena that are very poorly analyzed and
in many cases don't actually occur. The sociobiologist concludes
that behavior patterns are inherited, not knowing that only the
consequences of motor outputs, not the outputs themselves,
repeat. What does a geneticist really know about the actions
through which a bird catches a bug? You can inherit the
perceptual control systems that are capable of catching bugs,
but you can't inherit acts that happen to take you where a
particular bug is going next. The combination of narrow
expertise in one field and naive conceptions in every other
field leads to facile explanations that are right only at one
point.
Specialists must see the need for a model of behavior that
applies in all disciplines, even those in which the specialist
is not competent. Once the Artificial Intelligence researcher
understands exactly why organized behavior cannot be produced by
computing outputs, he or she will modify the AI model so it will
work correctly with more detailed systems actually capable of
organized behavior. Important effects of learning how perceptual
control theory applies in other fields will occur at the
boundaries between disciplines -- exactly where we need to work
if we are ever to have a unified science of life. At Control
Systems Group meetings, specialists from many fields hear other
specialists talking about the way perceptual control theory has
made them rethink the problems in a different field. Because of
the common understanding, this inevitably reveals one's own
hasty assumptions, and encourages still more rethinking.
One last remark about the CSG. The CSG does not represent any
one scientific discipline. It has no agenda of its own beyond
encouraging the application of perceptual control theory within
existing disciplines -- no agenda, that is, except perhaps
lowering the barriers between disciplines. The psychologists in
the group are still psychologists, the sociologists are still
sociologists, the therapists are still therapists, the engineers
still engineers. This is not a political movement nor an
alternative to established science. It is simply a vehicle for
promoting interaction among people interested in using or
learning more about perceptual control theory in any specialty
whatsoever. When all the branches of the life sciences have
assimilated and begun using perceptual control theory, the CSG,
its work accomplished, will have no further reason to exist.
In this presentation I have talked around perceptual control
theory, alluding to some of its conclusions without attempting
to justify or explain them. Learning perceptual control theory
can't be done by listening to a half-hour's talk. I hope that
some of you will find the promise of a unifying principle for
the life sciences appealing enough to go further into this
subject.
* * * * * * * *
Mary Powers, November 1992:
While the existence of control mechanisms and processes (such as
feedback) in living systems is generally recognized, the
implications of control organization go far beyond what is
generally accepted. We believe that a fundamental characteristic
of organisms is their ability to control; that they are, in
fact, living control systems. To distinguish this approach from
others using some version of control theory but forcing it to
fit conventional approaches, we call ours Perceptual Control
Theory, or PCT.
PCT requires a major shift in thinking from the traditional
approach: that what is controlled is not behavior, but
perception. Modelling behavior as a dependent variable, as a
response to stimuli, provides no explanation for the phenomenon
of achieving consistent ends through varying means, and requires
an extensive use of statistics to achieve modest (to the point
of meaningless) correlations. Attempts to model behavior as
planned and computed output can be demonstrated to require
levels of precise calculation that are unobtainable in a
physical system, and impossible in a real environment that is
changing from one moment to the next. The PCT model views
behavior as the means by which a perceived state of affairs is
brought to and maintained at a reference state. This approach
provides a physically plausible explanation for the consistency
of outcomes and the variability of means.
The PCT model has been used to simulate phenomena as diverse as
bacterial chemotaxis, tracking a target, and behavior in crowds.
In its elaborated form, a hierarchy of perceptual control
systems (HPCT), it has lent itself to a computer simulation of
tracking, including learning to track, and to new approaches to
education, management, and psychotherapy.
Control systems are not new in the life sciences. However,
numerous misapprehensions exist, passed down from what was
learned about control theory by non-engineers 40 or 50 years ago
without further reference to newer developments or correction of
initial misunderstandings. References in the literature to the
desirability of positive feedback and the assertion that systems
with feedback are slower than S-R systems are simply false, and
concerns about stability are unfounded.
The primary barrier to the adoption of PCT concepts is the
belief--or hope--that control theory can simply be absorbed into
the mainstream life sciences without disturbing the status quo.
It is very hard to believe that one's training and life work,
and that of one's mentors, and their mentors, must be
fundamentally revised. Therefore, PCT appeals to those who feel
some dissatisfaction with the status quo, or who are attracted
to the idea of a generative model with broad application
throughout the life sciences (plus AI and robotics). There are
very few people working in PCT research. Much of its promise is
still simply promise, and it meets resistance from all sides. It
is frustrating but also tremendously exciting to be a part of
the group who believe that they are participating in the birth
of a true science of life.
* * * * * * * *
THE EVOLUTION OF THE CONTROL PARADIGM
The PCT paradigm originates in 1927, when an engineer named Harold
Black completed the technical analysis of closed loop control
systems. He was working with the negative feedback amplifier,
which is a control device. This led to a new engineering
discipline and the development of many purposeful machines.
Purposeful machines have built-in intent to achieve specified ends
by variable means under changing conditions.
The explanation for the phenomenon of control is the first
alternative to the linear cause-effect perspective ever proposed
in any science.
The first discussion of purposeful machines and people came in
1943 in a paper called: Behavior, Purpose and Teleology by
Rosenblueth, Wiener and Bigelow. This paper also argued that
purpose belongs in science as a real phenomenon in the present.
Purpose does not mean that somehow the future influences the
present.
William T. (Bill) Powers developed PCT, beginning in the mid-50's.
In 1973 his book called "Behavior: the Control of Perception."
(often referred to as B:CP) was published. It is still the major
reference for PCT and discussion on CSGnet.
B:CP spells out a suggestion for a working model of how the human
brain and nervous system works. Our brain is a system that
controls its own perceptions. This view suggests explanations for
many previously mysterious aspects of how people interact with
their world.
Perceptual Control Theory has been accepted by independently
thinking psychologists, scientists, engineers and others. The
result is that an association has been formed (the Control System
Group), several books published, this CSGnet set up and that
several professors teach PCT in American universities today.
DEMONSTRATING THE PHENOMENON OF CONTROL
Few scientists recognize or understand the phenomenon of control.
It is not well understood in important aspects even by many
control engineers. Yet the phenomenon of control, when it is
recognized and understood, provides a powerful enhancement to
scientific perspectives.
It is essential to recognize that control exists and deserves an
explanation before any of the discourse on CSGnet will make sense.
Please download the introductory computer demonstrations,
simulations and tutorials, beginning with "demo1". See "World-Wide
Web" below for obtaining files via FTP and WWW.
THE PURPOSE OF CSGnet
CSGnet provides a forum for development, use and testing of PCT.
CSGnet PARTICIPANTS
Many interests and backgrounds are represented here. Psychology,
Sociology, Linguistics, Artificial Intelligence, Robotics, Social
Work, Neurology, Modeling and Testing. All are represented and
discussed. As of March 20, 1995 there were 146 individuals from 20
countries subscribed to CSGnet.
ASKING QUESTIONS
Please introduce yourself with a statement of your professional
interests and background. It will help someone answer if you spell
out which demonstrations, introductory papers and references you
have taken the time to digest.
POST FORMAT
When you are ready to introduce yourself and post to CSGnet,
please begin each post with your name and date of posting at the
beginning of the message itself, as shown here:
[From Dag Forssell (970212 1600)]
This lets readers know who sent the message, and when (sometimes
very different from the automated datestamp). It provides a
convenient reference for replies. When you respond to a message,
please use this reference (remove the word "From"), and quote only
relevant parts of the message you comment on.
THE CONTROL SYSTEMS GROUP
The CSG is an organization of people in the behavioral, social,
and life sciences who see the potential in PCT for increased
understanding in their own fields and for the unification of
diverse and fragmented specialties.
Annual dues are $20 for full members and $5 for students.
The Thirteenth North American Annual Meeting of the CSG will held
in Durango, Colorado, from July 30 to August 3, 1997. There will
be seven plenary meetings (mornings and evenings), with
afternoons, mealtimes, and late night free for further discussion
or recreation. Full details will be available on CSGnet or by mail
after April 1, 1997.
For membership information write:
CSG, c/o Mary Powers, 73 Ridge Place CR 510, Durango, CO
81301-8136 USA or send e-mail to powers_w@FRONTIER.NET.
ACCESSING AND SUBSCRIBING TO CSGnet
CSGnet can also be accessed via Usenet where it is listed as the
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For more information about accessing CSGnet, contact Gary Cziko,
the network manager, at g-cziko@uiuc.edu
WORLD-WIDE WEB
A number of documents (including a hypertext version of this one)
and MS-DOS and MacIntosh computer programs can be obtained via FTP
(ftp://lynx.ed.uiuc.edu/LRS2/CSG/Computer_Programs/) and the
World-Wide Web (http://www.ed.uiuc.edu/csg/).
ON-LINE DOCUMENTS
A large collection of extracts from CSGnet discussions can be
found at on the World Wide Web at
http://www.ed.uiuc.edu/csg/documents/docindex.html. In addition,
extracts from selected published works can be found among the
references listed below.
REFERENCES
Here are some selected books, papers and computer programs on
Perceptual Control Theory. For a very complete list of CSG-related
publications, get the file biblio.pct from the fileserver as
described above. See also the "PCT Introduction and Resource
Guide."
* * * * * * * *
Bourbon, WT, KE Copeland, VR Dyer, WK Harman & BL Mosely (1990).
On the accuracy and reliability of predictions by control-system
theory. Perceptual and Motor Skills, vol 71, 1990, 1331-1338.
The first of a 20-year series demonstrating the long-term
reliability and stability of predictions generated by the PCT
model.
W. Thomas Bourbon (1995). Chapter 8: Perceptual Control Theory.
In Herbert L. Roitblat & Jean-Arcady Meyer, Eds.: Comparative
Approaches to Cognitive Science. Cambridge, Mass: A Bradford Book,
The MIT Press, pages 151-172.
Chapter surveys applications of PCT modeling by Bill Powers and
Greg Williams (pointing, from the ARM/LITTLE MAN program); by
Rick Marken and Bill Powers (movement "up a gradient" by E.
coli), by Bill Powers, Clark Mcphail and Chuck Tucker (social
movement and static formations, from the GATHERINGS program),
and by Bourbon (tracking). The PCT model is contrasted with some
of the mainstream models and theories presented at the workshop.
Cziko, Gary A. (1992). Purposeful behavior as the control of
perception: Implications for educational research. Educational
Researcher, 21(9), 10-18, 27.
Introduction to PCT and implications for educational research.
Cziko, Gary A. (1992). Perceptual control theory: One threat to
educational research not (yet?) faced by Amundson, Serlin, and
Lehrer. Educational Researcher, 21(9), 25-27.
Response to critics of previous article.
Cziko, Gary. (1995). Without miracles: Universal selection theory
and the second Darwinian evolution. Cambridge: MIT Press/A
Bradford Book.
See Chap 8, "Adapted Behavior as the Control of Perception"
Ford, Edward E. (1989). Freedom From Stress. Scottsdale AZ: Brandt
Publishing. A self-help book.
PCT in a counseling framework.
Ford, Edward E. (1987). Love Guaranteed; A Better Marriage In 8
Weeks. Scottsdale AZ: Brandt Publishing.
Ford, Edward E. (1994). Discipline for Home and School. Scottsdale
AZ: Brandt Publishing.
Teaches school personnel and parents how to deal effectively
with children.
Ford, Edward E. (1996). Discipline for Home and School, Book Two;
Program Standards for Schools. Scottsdale AZ: Brandt Publishing.
Additional information focusing on the requirements for
successful implementation.
Forssell, Dag C., (1994). Management and Leadership: Insight for
Effective Practice.
A collection of articles and working papers in book form
introducing and applying PCT in the context of business and
industry.
Forssell, Dag C. (Ed.), (1995). PCTdemos and PCTtexts. Two DOS
disks 1.44 MB 3 1/2". May be freely copied. Also available at the
WWW site shown above.
PCTdemos holds eight different tutorial, simulation and
demonstration programs with documentation. PCTtexts holds 3+ MB
of essays, explanation, and debate.
Gibbons, Hugh. (1990). The Death of Jeffrey Stapleton: Exploring
the Way Lawyers Think. Concord, NH: Franklin Pierce Law Center.
A text for law students using control theory.
Hershberger, Wayne. (Ed.). (1989). Volitional Action: Conation and
Control (Advances in Psychology No. 62). NY: North-Holland.
16 of 25 articles on or about PCT.
Judd, Joel. (1992). Second Language Acquisition as the Control of
Nonprimary Linguistic Perception: A Critique of Research and
Theory. Unpublished doctoral dissertation, University of Illinois
at Champaign-Urbana. Dissertation Abstracts International, 53,
(7), #9236495.
Marken, Richard S. (Ed.). (1990). Purposeful Behavior: The control
theory approach. American Behavioral Scientist, 34(1). (Thousand
Oaks, CA: Sage Publications).
11 articles on control theory.
Marken, Richard S. (1992). Mind Readings: Experimental Studies of
Purpose. NC: New View.
Research papers exploring control.
McClelland, Kent. 1994. Perceptual Control and Social Power.
Sociological Perspectives 37(4):461-496.
McClelland, Kent. On Cooperatively Controlled Perceptions and
Social order. Available from the author, Dept. of Sociology,
Grinnell College, Grinnell IOWA 50112 USA.
McPhail, Clark. (1990). The Myth of the Madding Crowd. New York:
Aldine de Gruyter.
Introduces control theory to explain group behavior.
McPhail, Clark., Powers, William T., & Tucker, Charles W. (1992).
Simulating individual and collective action In temporary
gatherings. Social Science Computer Review, 10(1), 1-28.
Computer simulation of control systems in groups.
Petrie, Hugh G. (1981). The Dilemma of Inquiry and Learning.
Chicago: University of Chicago Press.
Powers, William T. (1973). Behavior: The Control of Perception.
Hawthorne, NY: Aldine DeGruyter.
The basic text.
Powers, William T., The Nature of Robots:
1 Defining Behavior BYTE 4(6), June 1979, p132-144, 7 pages.
2 Simulated Control System, BYTE 4(7), July, 134-152, 12p.
3 A Closer Look at Human Behavior, BYTE 4(8), Aug, 94-116, 16p.
4 Looking for Controlled Variables, BYTE 4(8), Sep 96-112, 13p.
Powers, William T. (1989). Living Control Systems: Selected
Papers. NC: New View.
Previously published papers, 1960-1988.
Powers, William T. (1992). Living Control Systems II: Selected
Papers. NC: New View.
Previously unpublished papers, 1959-1990
Richardson, George P. (1991). Feedback Thought in Social Science
and Systems Theory. Philadelphia: University of Pennsylvania
Press.
A review of systems thinking, including PCT.
Robertson, Richard J. and Powers, William T. (Eds.). (1990).
Introduction to Modern Psychology: The Control Theory View. NC:
New View.
College-level text.
Runkel, Philip J. (1990). Casting Nets and Testing Specimens. New
York: Praeger.
When statistics are appropriate; when models are required.
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