Happy New Year to everyone!!!!
Best, Dag
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 January 1, 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
continued:
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
newsgroup "bit.sci.purposive-behavior" (NOTE: You may have to set
your default news server to news.cso.uiuc.edu to read this group.)
To subscribe to the listserv version of CSGnet, and learn about
options & commands, subscribers and archives, send a message to
LISTSERV@POSTOFFICE.CSO.UIUC.EDU
Message: (Comments: Not part of your message)
Subscribe CSGnet Firstname Lastname Institution (Your OWN name)
help (Basic introduction to commands)
info refcard (Comprehensive reference of commands)
set CSGnet digest * (Deliver one day's worth every morning)
set CSGnet repro (Get copy of your own postings)
set CSGnet ack (Receive acknowledgements when posting)
query CSGnet (Your mail status & options)
review CSGnet countries (Subscribers & addresses, by country)
index CSGnet (List of archive files available to you)
get CSGnet LOG9702B (Get archive for 2nd week of Feb 1997,
shown here as an example only. Archives
can also be accessed via anonymous FTP
at postoffice.cso.uiuc.edu/csgnet).
* The alternatives are:
set CSGnet mail (Get messages as they are posted)
set CSGnet nomail (Stop the mail temporarily)
The Bitnet address for the list server is listserv@uiucvmd.
To remove yourself from the listserv version of CSGnet, send a
message as follows to LISTSERV@POSTOFFICE.CSO.UIUC.EDU
Unsub CSGnet
For the "unsub" command to work, the command must be sent with the
same return address used for the original "subscribe" command.
Messages to the entire CSGnet community should be addressed to
CSGnet@POSTOFFICE.CSO.UIUC.EDU
For more information about accessing CSGnet, contact Gary Cziko,
the network manager, at g-cziko@uiuc.edu
WORLD-WIDE WEB
A number of documents as well as MS-DOS and MacIntosh computer
programs can be obtained via FTP and the World-Wide Web (currently
under construction).
To use a browser, connect to gopher.ed.uiuc.edu and follow the
path:
Higher Education Resources/
Professional societies & journals/
Control Systems Group
or from your favorite server follow the path:
Other Gopher and Information Servers/
North America/
USA/
illinois/
University of Ill.--College of Education/
Higher Education Resources/
Professional societies & journals/
Control Systems Group
The WWW address for the CSG homepage (under construction) is
http://www.ed.uiuc.edu/csg/ (don't forget the final slash).
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.
Bourbon, W. Tom (In Press). Perceptual Control Theory. In: HL
Roitblat & J-A Meyer (eds.). Comparative approaches to cognitive
science. Cambridge, MA: MIT Press.
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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