INTRODUCTION TO THE CONTROL SYSTEMS GROUP NETWORK (CSGnet)
AND TO THE CONTROL SYSTEMS GROUP
Prepared by Dag Forssell 921118. Updated 930112
This introduction provides information about:
Our subject: Perceptual Control Theory
The evolution of the control paradigm
Demonstrating the Phenomenon of Control
The purpose of CSGnet
The Control Systems Group
Subscribing to CSGnet
How to obtain text and program files
OUR SUBJECT: PERCEPTUAL CONTROL THEORY
Here are two introductions by Bill and Mary Powers:
There have been two paradigms in the behavioral sciences since
the 1600's. One was the idea that events impinging on
organisms make them behave as they do. The other, which was
developed in the 1930's, is PERCEPTUAL CONTROL THEORY (PCT).
Perceptual Control Theory explains how organisms control what
happens to them. This means all organisms from the amoeba to
humankind. It explains why one organism can't control another
without physical violence. It explains why people deprived of
any major part of their ability to control soon become
dysfunctional, lose interest in life, pine away and die. It
explains what a goal is, how goals relate to action, how
action affects perceptions and how perceptions define the
reality in which we live and move and have our being.
Perceptual Control Theory is the first scientific theory that
can handle all these phenomena within a single, testable
concept of how living systems work.
William T. Powers, November 3, 1991
PERCEPTUAL CONTROL THEORY
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
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
Mary Powers, November 1992
THE EVOLUTION OF THE CONTROL PARADIGM
The PCT paradigm originates in 1927, when an engineer named
Harold Black invented the negative feedback amplifier, which is
a control device. This invention led to the development of
purposeful machines. Purposeful machines have built-in intent to
achieve consistent ends by variable means under changing
The discovery and formalization of the phenomenon of control is
the first alternative to the 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
The first specific suggestion on how to use the concept of
control to understand people came in 1957 in a paper entitled:
A General Feedback Theory of Human Behavior by McFarland, Powers
In 1973 William T. (Bill) Powers published a seminal book called
"Behavior: the Control of Perception," which still is the major
reference for PCT. See literature below.
This book spells out a complete model of how the human brain and
nervous system works like a living perceptual control system.
Our brain can be viewed as 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 and other interested people.
The result is that an association has been formed (the Control
System Group), several books published, this CSGnet set up and
that at latest count 16 professors are teaching PCT in American
DEMONSTRATING THE PHENOMENON OF CONTROL
The phenomenon of control is largely unrecognized in science
today. 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
It is essential to recognize that this phenomenon exists and
deserves an explanation before any of the discourse on CSGnet
will make sense.
Please download the introductory demonstration dem1a.exe, which
is an interactive program and/or rubberbd.txt, which is a text
telling you how to demonstrate the phenomenon to yourself and a
friend using only two rubber bands.
THE PURPOSE OF CSGnet:
CSGnet provides a forum for development, use and testing of PCT.
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 December 1992 there were
over 130 individuals from 18 countries subscribed to CSGnet.
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.
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 $45 for full members and $5 for students
An annual meeting is held in Durango, Colorado, on the campus of
Fort Lewis College. In 1993 it will begin in the evening of
Wednesday, July 28, and end Sunday morning, Aug, 1. There will
be 7 plenary meetings (mornings and evenings), with afternoons,
mealtimes, and late night free for further discussion or
recreation. Full details will be available on the net or by mail
after April 1, 1993.
Net subscribers find it useful to have thematic collections of
some of the network discussions, and it enables non-net members
to keep up with them. Threads from this net are published on a
quarterly basis in a booklet called the Closed Loop. These
booklets are distributed to members and are available
separately. A complimentary copy of Closed Loop will be sent
upon request. Back issues are available: Volume 1 (4 issues) is
$12. Single issues of Volume 2, beginning with Jan. 1992, are $6
For membership information and back issues of Closed Loop,
write: CSG, c/o Mary Powers, 73 Ridge Place CR 510, Durango, CO
SUBSCRIBING TO CSGnet
When you subscribe to CSGnet, you get this message,
CSGINTRO.DOC. But you may have received it from a friend who
printed it, seen it on a demodisk, or seen it on Usenet. To
subscribe, send a message as follows: (Internet address followed
by two message commands, one per line)
Subscribe CSG-L Lastname, Firstname, Affiliation, City, State.
(Lastname, Firstname, etc is optional commentary, but helpful).
("help" requests a list of most commonly used commands).
(The Bitnet address is: LISTSERV@UIUCVMD).
(This server is not sensitive to upper or lower case letters).
CSGnet can also be accessed via Usenet (NetNews) where it is
listed as the newsgroup bit.listserv.csg-l.
For more information about accessing CSGnet, contact Gary Cziko,
the network manager, at G-CZIKO@UIUC.EDU
HOW TO OBTAIN TEXT AND PROGRAM FILES
A number of ASCII documents and binary computer programs are
available on a fileserver maintained by Bill Silvert. It is
possible to download all these files via e-mail. If you are on
internet, it is easiest to obtain binary program files via
anonymous FTP. If you are on MCI mail, you have read about how
you can transfer binary files with Kermit or Zmodem protocols.
(Type help at the MCI mail prompt for directions). But the
server cannot send binary files over the internet mail network,
so download uue.scr first, then request the binary files
uuencoded as ASCII files. The Internet address for the server is
BIOME.BIO.NS.CA. CSGnet files are kept in the subdirectory
To get basic information and a current listing of available
documents, send a message as follows: (Internet)
"help" requests commands and explanations.
"ftp" asks details on anonymous FTP for internet.
"get csg/Index" requests the Index for the csg subdirectory.
Pay attention to letter case for commands! DOS is not dos.
As part of the index (of the csg directory), you may be looking
dem1a.exe 128437 Bill Power's demonstr of perceptual control
dem2a.exe 123649 Bill Power's modelling of control
uud.scr 53406 ASCII Compile uud.exe w DOS debug Dir @ end.
If you want dem1a.exe (uuencoded) to get a "live" demonstration
of the phenomenon of control, and the ASCII file uud.scr with
directions at the end on how to use DOS debug to compile uud.exe
to decode it, send the following message commands:
The uuencoded dem1a.exe will be sent in four parts. Remove
headers and use an editor to make it into one file (starting
with table and ending with end) before you use uud.exe to
restore the file. dem1a.exe is a self-extracting archive file.
Put it in it's own directory before you execute it. You get
complete documentation and a running program.
For a complete list of CSG-related publications, get the file
biblio.pct from the fileserver as described above.
Here are some selected books and papers on Perceptual Control
Theory (entries preceded by an asterisk are available from
The Control Systems Group, 460 Black Lick Road, Gravel Switch,
Powers, William T. (1973). _Behavior: The control of
perception_. Hawthorne, NY: Aldine DeGruyter.
The basic text.
Petrie, Hugh G. (1981). _The dilemma of inquiry and learning_.
Chicago: University of Chicago Press.
Ford, Edward E. (1989). _Freedom from stress_. Scottsdale AZ:
A self-help book. PCT in a counseling framework.
Hershberger, Wayne. (Ed.). (1989). _Volitional action: Conation
and control_ (Advances in Psychology No. 62). NY: North-Holland.
25 articles (not all PCT)
*Powers, William T. (1989). _Living control systems: Selected
papers_. Gravel Switch, KY: CSG Books. ($16.50 postpaid)
Previously published papers, 1960-1988.
Gibbons, Hugh. (1990). _The death of Jeffrey Stapleton:
Exploring the way lawyers think_. Concord, NH: Franklin Pierce
A text for law students using control theory.
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.
McPhail, Clark. (1990). _The myth of the madding crowd_.
New York: Aldine de Gruyter.
Introduces control theory to explain group behavior.
*Robertson, Richard J. and Powers, William T. (Eds.). (1990).
_Introduction to modern psychology: The control theory view_.
Gravel Switch, KY: CSG Book. ($25 postpaid)
Runkel, Philip J. (1990). _Casting nets and testing specimens_.
New York: Praeger.
When statistics are appropriate; when models are required.
Richardson, George P. (1991). _Feedback thought in social
science and systems theory_. Philadelphia: University of
A review of systems thinking, including PCT.
*Marken, Richard S. (1992). _Mind readings: Experimental studies
of purpose_. Gravel Switch, KY: CSG Books. ($18 postpaid)
Research papers exploring control.
McClelland, Kent. (1992). _Perceptual control and sociological
theory_. Not yet published. Available from the author,
Grinnell University, Grinnell, Iowa.
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.
Cziko, Gary A. (1992). Purposeful behavior as the control
of perception: Implications for educational research.
_Educational Researcher_, _21_(9), 10-18, 27. (and...)
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.
Introduction to PCT and implications for educational
*Powers, William T. (1992). _Living control systems II: Selected
papers_. Gravel Switch, KY: CSG Books. ($22 postpaid)
Previously unpublished papers, 1959-1990.