"Applying PCT" can mean extrapolating from controlled laboratory situations to living control systems in complex social situations.
Consider the model of manipulation by countercontrol. In the rubber-band demo of counter-control, or in a mouse-cursor experimental setup, the input signal goes to one and only one input function. In actual situations with living control systems, any given input goes to an indeterminate number of input functions. The difficulty is in attempting to extrapolate from the laboratory scenario with its (appropriately!) artificial limitations to a living situation with indeterminate complexity.
In an experimental setup, there typically is one controlled variable ("knot over mark", or "cursor aligned with mark") and qi is input to one comparator at the level of the hierarchy where the CV is controlled. All input signals are from the environment (nothing is imagined). A measured output quantity qo plus a measured disturbance quantity d together determine a measured input quantity qi. The structure of a control loop with a reference input r determines the value of the variable qo so that qi approximates r.
Consider the extrapolation to faithfulness and spousal attention.
[From Rick Marken (2001.09.23.0920)]
>If you knew that she uses faithfulness (o) to control some other
>variable (qi), such as how much attention you pay to her. Then you could
>disturb qi, by varying the amount of attention you pay to you wife (d),
>for example, and, thus, influence her level of faithfulness. This works
>as long as it's true that your wife is, indeed, controlling qi (your
>attention to her) by varying o (faithfulness) to compensate for d (your
>attentiveness). If it's true that your wife is, indeed, controlling qi
>in this way, then you can control her faithfulness (o) by varying d
>since, according to control theory o = -1/g(d). This is an S-R
>relationship -- d is the stimulus (S) and o is the response (R) that
>exists because qi is under control and qi = o+d.
'Faithfulness' is not a measurable output quantity. It might be a complex variable controlled by her, if she is kind of naive. But I think we should assume she recognizes that any demonstrations of 'faithfulness' that you don't perceive can make no difference to your attentiveness. Her 'faithfulness' has to be perceived by you to be means of her controlling your attentiveness to her. In fact, it must be be a variable controlled by you, or at least she must believe that it is, and she is controlling her perception of how you perceive her 'faithfulness'. So she is producing a number of outputs that constitute 'faithfulness'. Probably a great variety and number of different outputs, wouldn't you say? Smiling on one occasion. Not smiling on another occasion (different person present). And so on. What does it mean to say that these diverse outputs {qo1 .. qon} constitute 'faithfulness?'. What matters is that you perceive them as 'faithfulness'. How does your perception get to be something that she controls?
One possibility is that she imagines your perception of her. She imagines what it is like to be you perceiving her, and she imagines a perception of what she is doing from your point of view. Over time, getting acquainted, getting to know you better, she tunes this imagined perception of your perception of her. Imagining the perceptions of another person is I think what is called empathy.
Consider the case where she believes that you are controlling her faithfulness to you when in fact you are not. All you are controlling is her belief that you are controlling her faithfulness to you. Not much left of 'faithfulness' but her imagination.
You might propose that she simply does whatever it takes to control your attentiveness to her. But I don't think you could call that controlling faithfulness as means of controlling your attentiveness. Because 'faithfulness' is not her behavioral output. It is your perception of her behavioral outputs. Potentially any of her behavioral outputs can be construed as part of 'faithfulness' or as part of 'unfaithfulness'. Ask any jealous spouse. Ask Othello. Ask Desdemona. Ask Leontes and Hermione.
Now Leontes went nuts all on his own, but Iago did manipulate Othello. How? Not by countercontrol. Rather, by playing on the ambiguity of practically all perceptual inputs in a natural setting. Is that handkerchief a token of betrayal, or did she lose it? In my experience this kind of manipulation is far more frequent than countercontrol. "Appearances", I think they call it sometimes.
But that's a different topic, isn't it.
Bruce Nevin