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Making Sense of Behavior

The Meaning of Control

Please have a look at the content of this book
as if you were flipping pages in a store.

    About Bill Powers      








Preface ix  
1 Controlling 1  
2 Perceptual Control 17  
3 Levels 27  
4 Learning 45  
5 Hands-On PCT 59  
6 Inner Conflict 73  
7 Conflict Between People 91  
8 Reward and Punishment 109  
9 Where Do We Go From Here? 125  
10 Reference 133  
11     Possible Levels of Perception and Control 135  
12     An Application of PCT:
        The Responsible Thinking Process
13     Studies in PCT 167  





Humans find humans endlessly fascinating. Alexander Pope was more pontifical about it: "The proper study of mankind is man." Since you have opened this book, no doubt you have a similar sentiment, and no doubt you have already read many books and uncounted magazine articles about the nature of humankind. If you are a scholar of some years, you have read hundreds, even thousands. What can still another book promise?

For almost a century, it has been the custom among American psychologists to seek to understand human nature by watching what people do. Most books about human nature focus on human doings; they focus on nameable acts with beginnings and endings. Consider a television set. What does a TV do? It shows us moving pictures on its screen; that is the "behavior" we see. But we could spend an entire lifetime studying the action on the screen and never come to understand a thing about how a TV functions. This book does not focus on visible acts. It focuses on perception. It shows us how action comes about if and only if we find a discrepancy between what we are experiencing and what we want to experience.

In other books, authors who are concerned about morality tell us about good and bad actions, authors who care about influencing others tell us about actions we can take (so they think) to cause others to do what we want them to do, authors who care about the sheer drama of human action tell us tales of derring-do, and so on. Novelists, dramatists, historians, anthropologists, sociologists, psychologists, and others of many stripes describe and catalog for us the multifarious and unending parade of human behavior. It is not surprising that our fascination focuses on action, since visible, tangible action is what we easily perceive. But that focus cannot tell us how any human individual functions.


Philip J. Runkel
Eugene, Oregon
August 1997






This is a book about human nature, as we try to guess about it by watching human behavior. It's about a particular theory that seems to fit a great deal of what we see people doing and a great deal of our own private experience. A lot of people think that this is a pretty good theory.

But my object in this book is not to persuade you that the theory is right, either by itself or by comparison with other theories. My main objective is to tell you what the theory is and why it has been constructed as it is. I will tell you of the observations that I have thought needed an explanation, and of how this theory appears to explain them. You can decide for yourself whether the theory and the observations go together, and are important.

I'm writing this book as I would write to a friend, not as I would write to impress the editorial board of a scientific publication. Behind the theory you will find here is a considerable technical background and a few dozen papers in the scientific literature, but I assume that most readers won't care about that. My aim is for you to understand the theory, which my colleagues and I call "Perceptual Control Theory" or "PCT" for short. No technical background is needed; the basic facts and relationships you must understand are part of ordinary life, and I suspect that you already understand them. If you remember a little of your high-school algebra, that's wonderful, but you won't need it here.

There are places where you can read more in depth about PCT; a bibliography at the end of the book will give you an entry. While I'll try to avoid saying anything that contradicts a more detailed discussion of PCT, I'm thinking here only of people just getting started, who know little or nothing about it and aren't technically inclined. So I'll keep the discussion as simple and direct as possible, although not any more simple and direct than that. I am assuming that I'm talking to an intelligent layperson willing to put out a little effort to understand something new. If that sounds like a good contract, we can proceed.

A lot of people have helped me toward writing this book, not the least of whom are Perry and Fred Good, who nagged me into doing it, and Dag Forssell, whose efforts in supporting PCT have been expressed in many practical and time-consuming ways, the final form of this book being just one example of many. In addition, many people in the Control Systems Group, which is devoted to PCT, and on an Internet discussion group called CSGnet, have forced me to learn how to say what I mean more clearly, and some of them have offered detailed critiques of this book as it was in progress. Any list would be incomplete, but I am immediately (and randomly) mindful of Dick Robertson, Tom Bourbon, Phil Runkel, Rick Marken, Greg Williams, the Bruces Abbott and Gregory, Kent McClelland, Martin Taylor, Bill Leach... and I will stop the list there because the longer it gets, the more embarrassing it will be when I realize which respected colleagues I have left out.

But I will not leave out my wife Mary, who against all reason has loved me, trusted me, and helped me through all the 40 years of development behind PCT, and who now grows old with me, a respected teacher of PCT in her own right.

And with that, let us dive right into our subject with Chapter One.

Bill Powers
Durango, Colorado
May, 1997


Chapter 1



In which we explore a
closed circle of causation
that is involved in all
control processes

Perceptual Control Theory is about controlling. It's not about responding to stimuli, or planning actions and then carrying them out; it's not about effects of traumatic incidents on later behavior; it's not about particular things people do under particular circumstances. It's not about attitudes or habits or beliefs or tendencies. It's not about predicting. It's just about one kind of behavior that we can see people carrying out, called controlling.

Controlling is important because in the natural world only living organisms can do it. Many things in the nonliving world respond when things happen to them-a baseball hit by a bat flies enthusiastically through the air; a mousetrap responds to a touch by snapping shut. Many things in the nonliving world show complex patterns of behavior-iron filings on a card leap into arcs and loops when a magnet is brought underneath the card; stars form from dust and gas in a galaxy and go through complex life cycles ending in gigantic bangs or dark and silent whimpers. Nonliving things even reproduce themselves, as when a seed crystal in a solution creates an ever-growing tree of crystals of the same kind.

But none of these nonliving things can control anything. None of them can change their actions on something else to make the outcome repeat or remain the same in a changing environment. None of them can have or carry out intentions concerning what is to happen to them. Controlling is a unique process, unique to life (except, of course, for artificial control systems, built by living ones to imitate their behavior).


Chapter 2

Perceptual Control



In which we see that behavior
is the process by which we
act on the world to control
perceptions that matter to us

Perception plays a central role in controlling. This is why the theory behind this book is called Perceptual Control Theory, or PCT The emphasis in PCT is not only to understand control from an outside observer's point of view, as in engineering control theory, but to grasp how control appears to the controller-that is, to you and me, who occupy our own copies of this marvelous mechanism and participate in running it. Taking this point of view gives us a new slant on perception. But first, let's look at the most usual concept of perception, one that has caused many difficulties.

The External View of Perception

When we look at another person, we can see that person's body movements and the effects of those movements on the person and the environment. But we can't see the other person's perceptions. From neurology we know that there are sensory receptors in the person's eyes, skin, ears, joints, muscles, viscera, and mucous membranes, and that each tiny sensory ending generates nerve signals when the environment stimulates it. These nerve signals converge into the lower parts of the brain, where they give rise to more neural signals in a series of steps going upward through the brain to the highest levels. Logically, we know that all of human experience must be carried by these signals, these perceptual signals, including the experiences that are occurring right now as we read these words. So from this external point of view, it seems there is a physical body and a physical environment, with the other person's perceptions of those things existing invisibly inside the other person's brain.


Chapter 3




In which we find that control involves
different levels of organization, with
higher control systems inside
a person using lower ones
as the means of control

The idea of control of perception sinks in only slowly. At first, it gets in the way of everything. When you reach for a drawer to get a fork, what you've been reading here pops into your head, and you think "That's a perception of a drawer and a perception of a hand reaching toward it; the feeling of pulling the drawer open is a perception; I'm sorting through perceptions of utensils to find a perception of a fork, and now I'm trying to make a perception of my hand with a fork in it...." All this creates a condition of extreme self-consciousness and artificiality. But if you go around hanging the label "perception" on everything you experience, eventually everything will have the same label, and the label will become unimportant. You'll understand that it's all perception the way you understand that your hand has fingers, but most of the time that bit of knowledge will cease to be obtrusive and you can go back, almost, to normal life. Even a baby eventually gets over its fascination with the fact that hands have fingers, although it never forgets this fact.

Our current project, however, requires that we go on paying attention to perception and the way we control it, so we're still on duty and can't relax yet.

Once the basic idea of controlling perceptions starts to feel comfortable, most people come up with the same question. When you start to close your hand to form a fist, you have in mind a state of the hand different from the one you see and feel. You then do whatever it is you do to make the muscles work, and the perceived state of the hand changes until it matches the reference state. The question is about these reference states,


Chapter 4




In which learning is represented
as a way of controlling the things
that matter the most to us

We've seen now that behavior involves control, which involves a circle of causation. We've seen how control can occur at many levels, each level manipulating the reference conditions that lower-level systems are unceasingly trying to match with perceptions by acting on the world outside them (which includes all lower-level systems). By now, you must be itching to ask some questions that start with "But." I can't guarantee that all those itches will be scratched, but we're going to tackle a question now that may help explain how the system got the way it is, and why. We're going to extend the theory to include a new kind of control system: one that acts on the organization of behavior instead of the outside world.

Consider a crying baby. Why is the baby crying? Some standard answers are because it is hungry, because it is thirsty, because it is sick, because a diaper pin is sticking into it, because it wants its mother, because it needs burping, because it needs changing, or simply because it can. All of these answers are reasonable, and all of them are also, I think, wrong.

The main thing I see wrong in these answers is that they are all given in terms that an adult observer, but not a baby, would understand. The right answer, I think, is that the baby cries because something is wrong. When everything is right, the baby does whatever contented babies do. When something is not right, the baby has only one means of control available: a whole-body effort in which the eyes are squeezed shut, tears are squeezed out of tear-ducts, the muscles squeeze the limbs into rigidity, and the diaphragm squeezes the air in the lungs through


Chapter 5

Hands-On PCT



In which we play some games
to experiment with
real control behavior

We now have a fairly broad view of PCT, Perceptual Control Theory, that includes control of particular perceptions and a hierarchical system for controlling some perceptions as a means of controlling others. We have at least a rudimentary theory of reorganization that shows how the hierarchy of control might develop, and how its development relates to maintaining the well-being of the person. As far as I've been able, I've tried to base the theoretical aspects of this discussion on everyday experience, on facts about behavior that are accessible to anyone. But reading and experiencing are not the same; it's time we indulge in a little recreation and look into learning through doing.

There's a little game with endless variations that illustrates many of the basic principles of PCT. The equipment required is very simple: two people and two rubber bands. You can ask a neurosurgeon to sever your corpus callosum and split your brain into two independent personalities, and play this game with yourself, but I recommend that you find a friend and do it the easy way. The point of this game is to get some experience with (a) consciously observing yourself controlling, and (b) observing how you can interact with another person who is controlling. As you play the rubber-band game you will see all the basic principles at work, and get an understanding of them that words alone can't convey. After you've seen the basic idea, we'll go on to introduce the first important application of PCT to human problems, the problem of conflict.

To set up the game, you first knot the two rubber bands together by passing each through the other and pulling them


Chapter 6

Inner Conflict



In which we see what happens
when control systems
inside one person come into
conflict with each other

As we've just seen in the rubber band demo, a conflict can arise when two control systems attempt to control the same thing, but relative to two different reference levels. If one person succeeds in getting the knot over Dot 1, the other person necessarily can't be seeing the knot over Dot 2.

So the other person will try harder, dragging the knot toward Dot 2-which will, of course, drag it off of Dot 1, so the first person will also try harder. As this goes on, the rubber bands get longer and longer, eventually breaking.

Actually, I have seen the rubber band break only once, and that was because both people decided that they didn't care if it broke. Generally, at least one person will not want to break the rubber bands, and so will limit how hard he or she will pull. That person doesn't want a hand hurt when the rubber band breaks and snaps back, or just feels it would be wrong or wasteful to break the equipment.

This is a conflict between two people, but we will focus here on the conflict within one of the people, the one who wants the rubber band to remain whole, for whatever reason. This person has a dilemma: In order to keep the knot over the right dot, it is necessary to pull hard enough to keep it there. But as the other person continues to pull harder, "hard enough" gets close to "hard enough to break the rubber band." At that point the reference signal that says "no broken rubber band" comes into play, and the person becomes reluctant to pull any harder.

So now this person finds that the same "pulling on the rubber band" control system is being given two exactly opposite goals: Pull harder, and don't pull harder (or pull less hard). Pull harder because


Chapter 7

Between People



In which we see that the main cause
of conflicts between people is the
attempt by one person
to control another

Internal conflicts, although they can have serious consequences for the individual, can be relatively easy to resolve, given some help and a framework of theory in which to understand what is going on. The conflicting control systems are inside the same person; whichever way the solution goes, the same individual will benefit. When conflicts arise between two people, however, the best of all possible resolutions would leave both people better off, but that isn't as easy to achieve.

Let's begin working our way through this problem by stating what it is. A conflict between two people exists when the action used by one person to achieve or maintain a reference condition in perception causes a perception in another person to deviate significantly from the reference condition in the other person. In other words, the actions I use to get what I want prevent you from getting what you want. It's a true conflict if this works both ways-if your getting what you want likewise prevents me from getting what I want. The two people trying to pull the knot so it is over two different dots is the essence of the situation.

As we saw at the beginning of the previous chapter, conflict between people can lead automatically to conflict inside one or both people. The person who is most afraid of breaking the rubber bands goes into conflict first and can no longer keep pulling harder, so the other, bolder, person wins-the knot goes over the other person's dot. This is a very common outcome of conflicts between people, from a poker player jumping the bet to drive the other players out of the hand to nations at war escalating the intensity of fighting or using ever-more-horrible


Chapter 8

and Punishment



In which we see that the idea of
reward and punishment
stems from a misunderstanding of
human nature and a desire
to control other people

You better watch out,
You better not cry,
You better not pout,
I'm telling you why;
Santa Claus is coming to town.

At one time, psychologists who wanted to control other people's behavior thought that objects and events like candy or praise had inherent rewarding properties. If you administered a reward while someone was acting the way you wanted, or closer to it, the reward would "strengthen" the tendency to repeat that behavior.

The reason that psychologists thought reward works this way was that everyone thought it works this way. Reward and punishment were not inventions of psychology: They were part of folk wisdom handed down through the ages. Reward and punishment have always been thought of as means by which one person can control the behavior of another-a subject about which you probably know more now than you did two chapters ago. People do want to control each other; sometimes they really need to control others, sometimes it is profitable to do so, sometimes it gives one a sense of power and competence, sometimes it seems to be the only way to keep an orderly society. If it weren't for the need or desire to control others, the ideas of reward and punishment would probably never have arisen.

It's easy to see why not. Just consider reward from the standpoint of the person being rewarded (punishment is another subject that we'll get into later). If someone said, "I'll give you this five-dollar bill to tie


Where Do We Go
From Here?



In which we see PCT
as a new direction for the
development of psychology

Engineers invented control theory while trying to build machines that could imitate human beings controlling things. The basic concept and the principles of control theory have been around since the 1930s, when electronics was just starting to develop devices that did something beside play music or send messages. It's unfortunate that control systems weren't invented six decades earlier, or that psychology didn't wait another 60 years to turn into a laboratory science. A lot of trouble might have been avoided, and control theory might have started moving toward center stage in the life sciences a lot sooner.

What did happen was that the life sciences, lacking the central explanatory principle that is absolutely essential for understanding how organisms work, went ahead and tried to explain behavior anyway. The only model available during the last part of the 19th Century and the first part of the 20th was Newtonian physics, in which natural processes go from cause to effect in a simple straight line. Biologists, and after them psychologists, thought that the behavior of organisms could be explained in the same causal terms. Behavior, they thought, was the result of external influences acting on organisms, largely through their sensory nerves, just as masses are caused to move by external forces. It was thought that explaining behavior was just a matter of observing environmental conditions and seeing how they caused or altered the actions of organisms. If you had a big catalogue of stimulus conditions and the behaviors known to follow them, you could predict how any organism would behave, and by manipulating the environment, control that




Compiled and Edited by Dag Forssell

  Possible Levels of Perception and Control 135  
  An Application of PCT:
The Responsible Thinking Process
  Studies in PCT 167  
  Readings 167  
  PCT Demonstrations and Texts 170  
  Research 170  
  Applications of PCT 173  
  Videos Illustrating or Introducing PCT 174  
  Control Systems Group and Network 175  
  Books Placing PCT in Context 176  
  PCT Web Sites 176  
  Publishers 177  

Possible Levels of Perception and Control

William T. Powers



Chapter 3 was devoted mainly to getting across the idea of levels of perception and control. The basic idea was that a higher-level system acts to control its own perception by sending reference signals to lower systems—signals that tell them what to perceive. This is all neat and logical, but there's another approach that isn't so neat and logical: it's the one I actually used when trying to identify levels of perception during the 40 (and more) years of developing this theory. It's not easy to identify levels in a way that will hold up to close inspection. In 40 years of trying, I've come up with 11 levels, which is less than 1/3 of a level per year—and I've had to change my mind several times.

I will probably have to change it again.

What I'm trying to say is "Don't take these levels I propose too seriously." A lot of people talk about them, but few have tried to do any research to see if they're real. I think of them as a useful starting-point for talking about the hierarchy of control; they'll do until something better comes along.

Getting Started with the Levels

The first time I felt any sense of progress in identifying actual levels of perception came when I was considering the perceptions we call "objects." Here is an object sitting on the table in front of me. It's obviously a perception. But what is this perception made of? Here is the computer mouse: I can see its shape, and the buttons on it, and the cable coming out of it. Is that all?


An Application of PCT:
The Responsible Thinking Process


by Tom Bourbon

Discipline programs for schools are a dime a dozen, and most of them aren't worth one red cent. Discipline programs reflect the theories their creators believe, and most of them believe that behavior is an effect produced by prior causes. People who believe those cause-effect theories usually treat other people like objects whose behavior is controlled by forces beyond their own control.

That is certainly what we see in schools. People in one large group believe that reinforcement from the environment controls behavior. They use discipline programs that claim positive reinforcement allows teachers to control students' behavior. People in a second large group believe that thoughts control behavior. Some people in this group use discipline programs that claim positive aphorisms and slogans, and "cognitive exercises," allow teachers to control students' behavior. Others in this group use programs that claim teachers can control students' behavior by meeting all of their "psychological needs." People in a third major group believe that brain chemistry controls behavior. Members of that group often use discipline programs that come out of a bottle, in the form of drugs that experts say will control students' behavior.

Perceptual Control Theory (PCT), described by Bill Powers in this little book, is different from all of those traditional cause-effect theories. Powers explains that behavior is the way a person controls his or her own perceptions. There is a discipline program that reflects many of Powers's ideas. It is the Responsible Thinking Process, developed by Ed Ford (See Applications of


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