[From Rick Marken (2016.05.11.1550)]
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Richard Pfau (2016.05.09 13:55)]
RP: Fred Nickols’ query about disturbances (2016.05.07.1345 ET) and Rick Marken’s informative response (2016.05.08.0950) raised an interesting point in my mind about influences on control loop functioning. Those influences are both external and internal to the controlling system…
RP: Internal influences include perceptual signals, reference signals, error signals [and gain] – concepts that we routinely consider when discussing PCT.
RM: Good point. Though it’s not really the signals that influence the functioning of the control loop; it’s the functions that do the influencing: input, comparator, output.
RP: However, besides these, not usually considered are influences on the functioning of the internal control system functions themselves" – on functioning of the Input Function, Comparator, and Output Function.
RM: This is also a good point. Though I’m not sure all of the influences you list are actually internal influences. For example, I think “priming” (as I understand it) is an external influence – a disturbance. “Framing”, “reflective thoughts”, “prior learning”, “memory”, “expectations” and “self-efficiency” (as I understand them) are things that are done by the control hierarchy rather than being influences on it. And “overall affect” is a result of rather than an influence on the operation of the hierarchy of control systems, at least in theory.
RM: So that leaves “hormones”, “drugs”, “fatigue” and “glucose” levels as what I would consider actual internal influences on control system function (that are also external to the control hierarchy itself). MK (that’s Matti, I think) just posted a reference to a paper by Martin Taylor that shows the effect of two of those things – drugs and fatigue – on control system operation. I think there must be studies of motor control that show the effects of muscle fatigue on the functioning of a control system; muscle fatigues lowers the output gain of the control system. Off the top of my head I can’t think of any evidence for the influence of hormones on control loop functioning but it makes sense to me that they would, to the extent that hormones affect things like sensory function, synaptic connection and/or muscle function.
RM: So I believe there are internal influences on control system functioning. But I think that they are generally physiological variables and whatever effect they have is absorbed into the parameters of the control models we use to explain the control of perceptions of variables external to the control system whose state is influenced by factors in the control system’s environment.
Best
Rick
The attached diagram sheds light on some apparent influences on control system functions and their functioning that do not presently seem to be a part of general thinking and discussions about PCT loop processes. (Using an idea from cybernetics, perhaps this perspective might be considered a “second-order” exploration of PCT functioning???).
As can be seen by looking at the attached diagram, a number of internal mechanisms and factors seems to be either a part of, affect, or are otherwise related to control loop functions and their functioning. For example:
- Input Functions and resulting perceptual signals may be affected by one’s expectations, hormones, priming, drugs, previous learning, and other factors such as low glucose levels due to previous activity.
- Output Functions and resulting references and behavior may similarly be affected by what one has learned before (such as knowledge of what works or may work in a given situation), by recall of that learning, by priming of some responses, by fatigue, by drugs, and by how confident one is about successfully achieving a reference).
Some of the mechanisms and factors mentioned are at the “cell and molecular level” such as hormones, neurotransmitters, and drugs. Others at a more abstract level are descriptive concepts such as expectations, thoughts, and memory.
Although at different functional and logical levels, the mechanisms and factors indicated in the diagram can apparently help us think about the many internal influences on the operations of our control loops and resulting behavior and perceptions. Can’t they? And wouldn’t it be productive if some scholars investigated and reported on these influences as they relate to PCT?
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Richard S. Marken
Author, with Timothy A. Carey, of Controlling People: The Paradoxical Nature of Being Human.