A few posts ago I wrote a piece on Perceptual Control Theory and how it is being applied clinically to mental health by the likes of Tim Carey and Warren Mansell, in the form of Method of Levels therapy. Very basically, PCT argues we seek to control our perceptions not our behavior. A key feature is a negative feedback loop, such that every action feeds back to influence our perceptions, as we attempt to control the perception based on an internal reference (e.g. our goals). What I hadn't realised was just how significant and controversial the implications of PCT are for Psychology.
Below is the transcript of an interview with Richard Marken, who has spent the last 30 years of his career, trying to convince Psychology that it is in great need of a paradigm shift from the current open loop causal model to a closed loop control framework. If he is correct, the implications for Psychology would be radical and would require a complete revision of the current methodologies, concepts and ultimately the way we view ourselves as human beings...
Hi Rick thanks for talking with MancPsychSoc
Could we begin with you telling us a bit about yourself and how you became interested in psychology?
I am a research psychologist with a PhD in what is now called Cognitive Psychology. I guess I have always had a philosophical turn of mind. Like most psychologists I was interested in understanding people, although to be honest I got into psychology through a series of accidents. I enjoyed the psychology classes as an undergrad and did well in them. I also had a girlfriend who was in psychology so I became a psych major because she was! So primarily because I was interested in understanding human nature and it posed some interesting questions to me. I always had a scientific bent, so I was attracted to seeing how you could possibly understand behaviour in a scientific way.
Before we get into what PCT is, perhaps you could give us a brief overview of the open loop model that is currently used in behaviourism and cognitive neuroscience?
It turns out that really all social science research, but certainly all behavioural research of any kind, whether it's done by people who call themselves Behaviourists, Cognitive Neuroscientists or whatever, is based on what I call a causal model or more formally the general linear model of statistics. This is the basis of all research that is done in psychology.
This basic model is borrowed from the physical sciences. Some people conceive of it as the scientific model - it is science - so they think there is no alternative to it. They therefore think of all the theories in Psychology as being different theories but I argue there is a common model underlying all different theories in behavioural sciences and that is the general linear model. Which is what you learn when you learn research methods in psychology if you become a researcher and you can look it up in any stats book.
Another way to look at the current model, is as an input-output model. It’s a model that is kind of confirmed by the way the nervous system works. You have afferent neurons carrying sensory inputs into the central nervous system and efferent neurons taking information out to the muscles. So there is an input-output organisation apparently to the nervous system.
The basic assumption of the model of how behaviour works is the same as the model of how a ball rolling down a plain works. It is cause and effect. Gravity causes the ball to accelerate and stimuli cause us to behave. That is what I would argue is the basic model in the behavioural sciences.
So what is Perceptual Control Theory and the Closed Loop Model it implies?
I would say that the first thing about Perceptual control theory is that PCT is based on an observation that has never been made before in Psychology, and that is that behaviour itself is a process of control. In conventional Psychology, behaviour is considered an output emitted by the organism. PCT views behaviour as results that are controlled by the organism. For example, the conventional view is that a behaviour like lifting a book, is an output produced by the organism; the last step in a causal chain that begins in the brain. PCT sees this same behaviour as a controlled result of output; a result that is produced consistently only because outputs vary appropriately to counter disturbances, such as differences in the weights of different books, which would prevent such consistency if the same muscle force outputs were produced every time the book was lifted.
The fact the consistent behaviours – such as lifting books, opening doors, driving without hitting other cars – are produced under constantly varying circumstances, is evidence that the “doings” that we call “behaviour” are controlled results of appropriately varying outputs.
Once you see that behaviour is control, then you realise that you need a theory that accounts for how this control works, how are people able to exert this control. How do people produce just the right outputs - the muscle forces and actions - that produce consistent results in the face of unpredictable and often undetectable variation in the environment in which they are behaving?
So that’s where PCT starts. There was an influence from cybernetics and control engineering - particularly control engineering because this is the field where the theory of control was developed. In engineering the theory was applied to the controlling done by inanimate objects, such as a thermostat. PCT developed out of the realization that, like thermostats, organisms are also control systems – living rather than artificial control systems.
So control theory was out there before Bill Powers’ came along and applied it to the controlling done by organisms – an application of control theory that came to be known as PCT. What is unique to Powers’ theory is that PCT applies control theory to behaviour correctly. Control Theory has been and still is applied to behaviour in Psychology but it has not usually been applied correctly, in terms of how the theory is mapped to behaviour. Since non PCT control theorists treat behaviour as an input output process ,control theory has been applied to behavior in a way that makes it seem like it’s the environment doing the controlling, not the organism itself.
The innovation of PCT is to apply Control Theory properly to the controlling that people (and all living organisms) do, and what you find when you apply Control Theory properly to behaviour is that organisms are controlling perceptual representations of the results they intend to produce; that is, behaviour is the control of perception. That’s the interesting and exciting aspect of PCT for me because it opens up a whole new way of looking at and studying behaviour.
What is the behavioural illusion?
When you apply Control Theory properly to the controlling people do, when you look at controlling from the outside, it often looks like stimuli are causing behaviour and that happens when you see a disturbance to a controlled variable resulting in compensating action from the person. But since you don’t always see the controlled perception, it looks like the disturbance causes the behaviour but it causes it via its effect on the control variable. So there is a behavioural illusion that stimuli cause responses but stimuli only appear to cause responses when those stimuli are disturbances to the variables people control.
For example, reflexes. There is a control system that controls the amount of light hitting the retina. So if you vary the amount of light going into the eye those changes in stimulus will lead to changes in the pupil size. The change in pupil size is an output that is protecting this controlled variable - the amount of light on the retina – from variations in this disturbance (the amount of light outside the eye). So reflexes are an example of the behavioural illusion.
It looks like stimuli are causing response - that light variations cause variations in pupil output directly, like there’s a direct causal link - but they don’t. The link exists because of the fact that the light is a disturbance to a controlled variable (the amount of light on the retina). And once a person stops controlling that variable – if one could stop controlling the amount of light hitting the retina - the stimulus no longer has an effect on the response. The apparent causal path from stimulus to response only exists, according to Control Theory, because the stimulus is a disturbance to something that is under control by the organism – a controlled variable.
But presumably behaviour involves controlling many different factors at the same time...
The theory itself tries to account for all behaviours. So we imagine that there is a hierarchy of control systems controlling many different perceptions – from those as simple as the tension in your muscles or angle in your joints to others as complex as your personal relationships or your political persuasion. So the idea is that we control all kinds of perceptions simultaneously relative to internally specified references for what those perceptions should be.
Because we are controlling for many different perceptions at the same time at all different levels, we can end up trying to control perceptions that are incompatible with each other. So we can end up having references for different states of the same perception and that results in conflict. And in fact conflict ends up taking away our ability to control. This is what I call the paradox of control: conflict is a uniquely control phenomena because it results from the fact that we are trying to control for a perception with inconsistent reference levels. So conflict results from our ability to control and it is also what interferes with our ability to control.
PCT also imagines there to be this process of reorganization that is similar to what people think of as learning. You have to learn to control - what to perceive and what level to keep those perceptions at to achieve higher order goals. Reorganisation is what builds properly designed control systems and it also fixes up the current organisation of existing control systems so as to minimize or eliminate conflict. Reorganisation is what therapists, such as Tim Carey and Warren Mansell , take advantage of in Method of Levels (MOL) therapy to help people solve their own conflicts.
Can you tell us a bit about your research and the evidence base for PCT?
For the first 10 to 15 years, most of my research was aimed at demonstrating principles of control that were inconsistent with the current open loop causal model of behaviour. I used very simple tracking tasks because in these tasks the variables are very easy to see and keep track of. Unfortunately, using these simple tasks led people to believe that control theory was only relevant to the “Motor behaviour” seen in these tasks.
In the mid 90’s I ran into the research on how people catch fly balls, which seemed like a more interesting behaviour. And in fact it turns out that people catch fly balls by controlling certain optical variables. I got involved in developing models for existing data on catching fly balls. So catching balls (or, more generally, object interception) has been one of my main substantive areas of research over the last 10 years or so.
Another piece of research that was very interesting, that I did some modelling on, was done by this guy Mechsner, who published an article in the very prestigious journal Nature. Mechsner did some very clever studies, in one of which he had people turn handles under a table to keep two flags that were visible on top of the table rotating in synchrony. The gears connecting the handles to the flags required the subject to move the handles out of phase in order to keep the flags moving in sync. So you had to vary the rate of motion of your hands in a very odd way - if somebody asked you to move your hands in that way it would be very hard to do. But it turns out that you can do it very easily (and the control model does it very easily) by simply controlling the perception of symmetry of the flags which generates the appropriately phased hand movements based on the error resulting from any difference in the symmetry movement of the flags. I have a control model of the behaviour in this experiment up on the net.
So in my research I’ve tried to show how closed loop models work and can account for the data rather nicely. But most of the data that has been collected in psychological experiments is not ideal for using PCT type models for two reasons. One is that it’s collected in the context of the open loop model so you have to guess at what might be the variables the subjects are controlling and these variables can often be difficult to indentify. The other bigger problem is that most research in Psychology is done on multiple subjects so you are really looking at the average behaviour of many subjects who are often behaving in quite different ways. So a model would be a model of the behaviour of a non-existent average human.
So the best evidence for PCT comes from studies such as the ball catching experiments or Mechsner’s nifty experiments. In these little studies, there is clearly a variable that is being controlled, there are clear disturbances and you can quantitatively get measures of all these variables in order to design models to explain the behaviour see in them.
What should the new methodology be? Testing Control Variables?
Testing for controlled variables is definitely the new methodology, because the main thing you need to know in order to understand the behaviour of a control system is what variables it is controlling. Therefore, PCT reorients research in a way that most psychologists would not find appealing because they are looking for the variables that control behaviour. Control theory says that what we should be looking for are the variables – controlled perceptual variables – that behaviour controls.
I think the outfielder research is a good example of that. There are three clear hypotheses about what perceptual variable outfielders control. There is the Linear Optical Trajectory model, which says that they control for keeping the optical projection of the ball moving in a straight line. There’s the Optical Acceleration Cancellation model which says you try to keep the acceleration of the ball at zero. And there is my theory, the Control of Optical Velocity model, which says fielders try to keep the optical velocity of the ball at zero. So there are three different theories of what the fielder is trying to control and there are ways to test these different theories and it turns out my theory is right!
But I am not so much interested in being right as I am in showing that this kind of research – testing for controlled variables – is the kind you would do from a control theory perspective. And you do it by producing disturbances to the hypothetical controlled variable and, in the fielder research, that is done by varying the actual trajectory of the ball that is being caught and seeing whether that disturbance has an effect on the hypothetical controlled variable.
Can you tell us a bit about your books, mind readings and more mind readings?
These books are collections of my mainly published and a couple of unpublished papers. In the early 1980s somebody suggested I might put together the papers I have already published to supplement the more theoretical book on PCT – Behavior: The Control of Percpetion – by Powers. My books are all mainly descriptions of research plus a couple of modelling papers, which test the PCT model. I put the first collection together in 1982. If you look at the book you will see there is are sections describing research on many of the basic topics in PCT: the nature of control itself as a phenomenon, whether behaviour is open or closed loop, hierarchies of control, applied PCT and so on.
I was surprised to find that my published research covered a pretty broad range of topics. So I collected the papers together as an archival resource of research related to PCT. I think they are the only two books in the world that describe the kind of research that one would start doing from a conrol perspective. I hope that smarter people than me will read them and run with the ideas in them and do some much more interesting research in more substantive fields
You mentioned that PCT hasn’t really been taken seriously by psychologists, why do think this is?
I think there are several reasons. The implications of PCT are devastating for the current way research is done in Psychology. So, if you took PCT seriously you would have to seriously consider changing all the textbooks, changing the way the research methods course it taught and get rid of the statistics course and turning it into a quantitative modelling course. It would be a huge change in the institutional teaching of psychology. PCT does provide a very radical threat to the current framework and establishment of Psychology.
Secondly, people doing psychology have careers and PCT wouldn’t necessarily help them do what they’re doing better; the implication of PCT for psychologists is ‘change what you are doing completely’. So psychologists do not take it seriously because it is not worth it to them.
These are practical reasons for rejecting PCT and of course psychologists would not couch their objections in those terms. I tend to get two common responses to paper I submit That reflect the more public objections to PCT. One is that PCT is nice but it applies only to the tracking tasks. The second that they 'already know that...’ - Bill Powers called it the ‘nothing but’ syndrome.
So PCT is not taken seriously because it is a serious threat to conventional Psychology therefore you’re not going to see any big change in Psychology come easily and we haven’t. I don’t know when that change will happen but I think it will have to happen because behavior is demonstrably a process of control. Part of the trouble is that because of the behavioural illusion, people are able to do research within the causal model and get satisfactory results.
If closed loop methodology is correct what does this specifically mean for how we should view past experimental research based on the open loop general linear model?
I think most of it would have to go. I mean there’s tons of journals filled with all this research but there were journals filled with alchemy studies before chemistry came along!
I think you can get ideas about what controlled variables you might want to start testing for from looking at past research, because conventional psychologists are still studying the control systems but from an open loop perspective.
But once PCT is taken seriously psychologists will see that it demands a completely new framework or paradigm for psychology to work within.
If and when PCT is established what do you see as the important research areas for yourself/PCT in the future?
What I have been doing is trying to demonstrate the principles of control and how they apply to behaviour in very abstract simple experiments. The kind of research that would be done next would have to be based on this closed loop model, trying to identify the controlled variables involved in specific behaviours.
As I have mentioned, the object interception research is a step in the right direction. I am doing some work with a researcher on object interception, doing some modelling for his data and, based on my modelling, I have discovered some interesting next step research to do in terms of changing the feedback connection between the interceptor and the object they are trying to intercept that would provide a nice test of the model.
Some of the research I would like to do is to create artificial environments on a computer so that you can create PCT type disturbances and test for controlled variables in more realistic environments, where you have quantitative control over aspects of the simulator environment.
What are the implications of PCT for how we should conceptualise the mind?
I think the current conception of the mind is that of it a kind of computer. But whether you think of it as a classical computer or some kind of analogue device, the basic concept of the mind in Psychology is that the mind is a transfer function; it transforms what comes into a person into what they do. It is like a computer in the sense that the world types stuff in and you produce an output in the form of behaviour.
The PCT concept of the mind is quite different. PCT views the mind as a set of specifications for the way your perceptual world should look (and sound and feel and taste). The mind is a specification producer. You are producing these specifications autonomously, on your own; they are not shaped or guided by inputs from the environment. It is you who specifies who you should be married to, what food you should be eating and so on.
So the mind, according to PCT, is an input specifier rather than a transformer of input into output.
If you could recommend one book (other than your own) what would it be?
I would recommend Bill Powers’ “Behaviour: The control of perception”. He also wrote another book called ‘Making Sense of Behaviour’ which is gives a much more elementary treatment of PCT. Bill is a great writer, he is very articulate and very smart. I do a course on PCT as a seminar and I use his ‘Making Sense of Behaviour’ book as the text.
From your experience in psychology, what advice would you give to students?
I would say to learn and have a good grasp of the basics, but to think critically and always have a copy of PCT in your back pocket...
Richard Marken's website
Two great websites on PCT here and here
Warren Mansell's Youtube channel on PCT