Rick,
this topics was once “chewed” on CSGnet. So I’ll just repeat the major points.
- If we want to do any research on PCT we have to understand what control in PCT means
W.T.Powers (B:CP, 2005):
CONTROL : Achievement and maintenance of a preselected state in the controlling system, through actions on the environment that also cancel the effects of disturbances.
From perspective of definition of control in PCT there is no controlled varaibles in external environment that could be controlled by “controlled behavior” as Rcik.Marken (R.M.) wanted to show… There are just effects to environment that Liivng organisms produce (see definitions of control).
2, The beggining of the Cybernetic Model paper that is mentioned in R.M. contribution does not reflect the main point of the article as the conclussion of the Cybernetic Model paper explicitelly define :
W.T.Powers LCS I, p. 175-176).
Reference state can not exist under the old cause-effect model. They refer, as far as external observations are concerned only to future states of the organism or it’s environment. They cannot affect present behavior, and they must be treated simply as outcomes of events caused by prior events. The flaw of this reasoning is hard to understand if one does not know (as the founders of scientific psychology did not know) of organizations capable of complex internal activities that are essentially independent of current external events. By ruling out the possibility of significant causes of behavior inside the organism, where they could not be observed, early behavioral scientist in effect commited themselves to a whole chain of deductions following from the assumption that everything of significance with regard to behavior could be observed from outside of organism. They were betting everything on the assumption that such internal causes would never be found to exist.
- Experiments about “controlled variables” that R.M. presented in tabel has wrong concept as was explained later in mentioned Cybernetic Model paper.
If we look at the first example of the table : open door – grasp, pull – angle of door – 80 degrees we can see that it is contradicting to W.T.Powers concept of PCT :
W.T. Powers : (LCS I, p. 176, para.2) :
There is one explanation for the existence of reference states that has been proposed over and over the centuries : they are determined by the intensions of the behaving organism. The driver has, inside him, the intention that the door be open. He acts to achieve this purpose, doing whatever is required (if possible) to achieve it…
It’s obviuos that the driver’s intention is not to open the door for certain amount of angle (80 degrees) or to search any “controlled variable” outside as RM concept predicts, but is clearly tha driver will open the door that is defined by his internal states (control inside organism) which driver wants to experience not “bring” some external “controlled variables” into reference state. That’s also the main point in PCT diagram (LCS III, 2008).
- So how PCT as scientific theory essentially works :
W.T. Powers (1998) :
Our only view of the real world is our view of the neural signals that represent it inside our own brains. When we act to make a perception change to our more desireble state – when we make the perception of the glass change from »on the table« to »near the mouth« - we have no direct knowledge of what we are doing to the reality that is the origin of our neural signal; we know only the final result, how the result looks, feels, smells, sounds, tastes, and so forth…It means that we produce actions that alter the world of perception…
The research work in PCT should be directed into exepriments that would show how PCT control loop works or how control in organisms is accomplished
W.T. Powers (B:CP, 2005, LCS III, 2008)
A. CONTROL : Achievement and maintenance of a preselected state in the controlling system, through actions on the environment that also cancel the effects of disturbances.
B. OUTPUT FUNCTION : The portion of a system that converts the magnitude or state of a signal inside the system into a corresponding set of effects on the immediate environment of the system
- the output function shown in it’s own box represents the means this system has for causing changes in it’s environment.
C. FEED-BACK FUNCTION : The box represents the set of physical laws, properties, arrangements, linkages, by which the action of this system feeds-back to affect its own input, the controlled variable. That’s what feed-back means : it’s an effect of a system’s output on it’s own input.
D. INPUT FUNCTION : The portion of a system that receives signals or stimuli from outside the system, and generates a perceptual signal that is some function of the received signals or stimuli.
E. COMPARATOR : The portion of control system that computes the magnitude and direction of mismatch between perceptual and reference signal.
F. ERROR : The discrepancy between a perceptual signal and a reference signal, which drives a control system’s output function. The discrepancy between a controlled quantity and it’s present reference level, which causes observable behavior.
G. ERROR SIGNAL : A signal indicating the magnitude and direction of error.
- The main goal in PCT.is to maintain organisms functioning with negative feedback control which is contained in definitions of PCT control loop above.
W.T.Powers (LCS III, 2008) :
In this book I have only one goal : to establish in the mind of the reader the literal reality of negative feed-back control as the basic organizing principle of human behavior. Human beings do not plan actions and then carry them out; they do not respond to stimuli according to the way they have been reinforced. They control. They never produce any behavior except for the purpose of making what they are experiencing become more like they intend or want to experience, and then keeping it that way even in a changing world. If they plan, they plan perceptions, not actions. If they respond to stimuli, they do so in order to prevent those stimuli from affecting variables they have under control. The root, the core, of the behavior of living systems is negative feedback control, at every level of organization from RNA and DNA to a spinal reflex to a mental concept of physics. Negative feedback control is the basic principle of life.