[Attachment Removed] Formal PCT Model - Hammer and Nail

[From Fred Nickols (2015.11.13.0755)]

One of the late, great figures in my field of performance improvement is noted for saying, “A good example is worth its weight in gold.”

Below is the formal PCT model with most of the explanatory text removed and the hammer and nail example inserted.

Comments? Corrections?



Fred Nickols, CPT


“Assistance at a Distance”

The Knowledge Workers’ Tool Room

Be sure you measure what you want.

Be sure you want what you measure.

image001.emz (11.8 KB)

[From Rick Marken (2015.11.13.1130)]



Fred Nickols (2015.11.13.0755)–

FN: Below is the formal PCT model with most of the explanatory text removed and the hammer and nail example inserted.

Comments? Corrections?

Richard S. Marken

Author of Doing Research on Purpose.
Now available from Amazon or Barnes & Noble

RM: This is great, Fred! I would only change what you call the perceptual and error signals. Saying that the perception is “Nail head protrudes 1/2 inch above the deck” doesn’t capture the fact that the perceptual signal is a variable, just like the variable being perceived, which you correctly call “Nail head position” (probably better to call it “Height of nail head above plank”). So I would call the perceptual signal something like “Perceived height of nail head above plank” and the error would be “Difference between perceived and desired (reference) nail head height above plank”.

RM: Notice, also, that there are two aspects of the “hammering a nail” behavior that are in the environment and, therefore, visible to an observer: Q.i and Q.o. When we see the behavior “hammering a nail” we are referring to both Q.i (the controlled variable) and Q.o (the means used to hammer the nail). We are also implicitly referring to the reference state of Q.i since the person is not hammering the nail just to hammer it but to bring it to a reference state, flush with the plank. So when you say a person is “hammering a nail” you are referring to the controlled variable, the reference state of that variable (or just that the variable has a reference – or goal – state) and the means used to bring the controlled variable to the reference.

RM: So it’s not just Q.o – swinging the hammer – that you are talking about when you say that a person is “hammering a nail”. Indeed, saying that Q.o is the only thing we mean when we talk about a behavior is clearly wrong in this case. When we say that a person’s behavior is “hammering a nail” we are not saying that what the person is doing is “swinging a hammer”. People swing a hammer to produce many different consequences (to control many different variables); I’ve swung a hammer to try to ring a bell and win a prize at the state fair, to close a warped door, etc. So when we talk about any particular behavior we are talking about what is listed in the columns of Table 1, p. 172 of LCS I: the variable controlled (Q.i), the reference state of that variable, r, and the means (Q.o) used to achieve that state .We are never talking about just Q.o (what are called “outputs” or “actions” in PCT). Indeed, in many cases, we are only talking about “behavior” as the controlled variable and its reference state. For example, when we say a person is “walking” we are talking about changes in the reference states of limb and torso positions that are a controlled consequence of muscle forces that we can’t see. In other words, the “behavior” we are talking about is only observable Q.i’s and their reference states (the changing positions of arms, legs and torso).

RM: The nice thing about the Figure above (and all PCT diagrams, for that matter) is that it nicely separates the observable phenomenon to be explained – the behavior that is Q.i and Q.o, the variables out in the ENVIRONMENT – from the theory that explains it - the CONTROLLING SYSTEM. In PCT the model of the ENVIRONMENT is just as important as the model of the SYSTEM that explains the behavior that is observed in the environment. The reason I am carrying on about getting the analysis of behavior correct is because it is not just the model of the SYSTEM that distinguishes PCT from other psychological theories; it’s the model of behavior itself that distinguishes it.

RM: Behavior is something that we see happening in the environment. Bill’s huge insight was that what we are seeing as behavior is a process of control, in the sense that we are seeing variables being consistently brought to and maintained in reference states, protected from disturbance. This is not the way behavior is viewed in conventional psychology. The model of behavior in conventional psychology includes only Q.o in the diagram above. There is no Q.i – no controlled variable – so there is no need for control theory in conventional psychology because there is no control to be explained. When control theory is applied, it is applied to the model of behavior that includes only Q.o; that is,non-PCT control theory is used to explain “control of output” by the environment.

RM: So it is the model of the nature of behavior itself that distinguishes PCT from all other theories of behavior. PCT is based on an understanding of the fact that behavior is control – that it objectively involves controlled variables, Q.i. This is where conventional psychology and PCT diverge – before the theorizing even starts. They diverge regarding that phenomenon they are trying to explain. PCT aims to explain control, in particular the existence of reference states of controlled variables,Q.i; conventional psychological theories explain generated output, in particular variations in actions, Q.o.

Best regards