One popular way to describe the difference between PCT and other theories of behavior is to say that while other theories hold that perception controls behavior PCT states that behavior controls perception. I’m sure I have described PCT in this way myself at one time or another, as has Bill Powers. But I now think this way of describing PCT can be misleading in a way that “pulls a red herring across the path of progress” in the study of living control systems (the subject of my recent book on the topic).
I think this way of describing the PCT view of behavior encourages researchers to assume that conventional methods can be used to study behavior since “behavior controls perception” suggests that the only difference between the PCT and conventional view of behavior is apparently the direction of causality between perception and behavior. I think this was of describing the PCT view of behavior might also lead researchers to assume that the perception controlled by behavior is difficult or impossible to observe when, in fact, it is the observation of controlled aspects of the environment that are is the reason for the development of the PCT view of behavior as the control of perception.
The phrase “behavior controls perception” is problematic because it suggests that PCT says that the observable behavior of organisms controls controls their perceptions, which are unobservable. The problem with this is that nearly all of the observable behavior of organisms involves the control of perceptions; behavior itself IS the control of perception. This is the point I tried to make in my talk a couple years ago at a meeting of the Cybernetic Society. The talk is available here. The animation in that talk shows that the behavior we see as “sipping tea” is actually the visible “side effect” of the process of controlling a perception of the position of the cup relative to a varying reference.
The means used to control this perception are the actor’s muscle forces that affect the position of the cup. These muscle forces could be seen as “behaviors that control the perceptions” – in this case the perceptions involved in sipping tea" – but I think this is still a problem since the muscle forces themselves are controlled perceptions. So, I think that it’s better to refer to the means used to control perceptions as “actions” or “outputs” and reserve the term “behavior” to refer to informal description of what we see organisms doing, such as “lifting a cup”, “sipping tea” or “inciting a riot”. The term “behavior” refers to what an observer perception of what an organism is doing.
My preference now is to describe the PCT view of behavior as “behavior is organized around the control of perception”. The term “organized” refers to the control loop that keeps a perception under control. When described in this way we can see that “behavior” refers to the two main observable components of this loop: the actions that keep a controlled perception under control and the controlled variable, which is the observer’s perception of the controlled perception itself.