Notes on Regulation:

In today’s post, I am looking at the idea of regulation. I talked about direct and indirect regulation in my previous post. In today’s post, I will look at passive and active regulation.

Ashby viewed a system as a selection of variables chosen by an observer for the purpose of sensemaking and control. The observer is looking not at what the system is (what the variables are), but at what the system does. In other words, the observer is interested in the behavior of the system. The observer is interested in influencing the behavior so that the system is maintained in certain desirable states. Of all possible states, the system can be in, the observer would like to keep the system in a chosen few states. To achieve this, the observer has to model the behavior of the system. As J. Achterbergh and D. Vriens note:

we should “model” the behavior of this entity (system) in such a way that we can understand how it behaves in the first place, and how this behavior reacts to “influences.” One could say that (at least) two kinds of influences on behavior (input) can be discerned: “disturbances” – causing the concrete entity to behave “improperly,” and “regulatory actions” – causing “proper” behavior (by preventing or dealing with disturbances).

The general understanding is that the environmental disturbances cause the system to behave improperly. The role of the regulator is to prevent the disturbances from reaching the essential variables of the system. The controller sets the target for the system, while the regulator acts on realizing the target. An easy example to distinguish the controller and the regulator is with a thermostat. The homeowner in this case is the controller, while the thermostat is the regulator. The homeowner decides the range for the thermostat, and all the thermostat can do is turn on or off depending upon the temperature inside the house. The regulator is not able to change the target; only the controller can change the target.

The goal of the regulator, as noted above, is to ensure that the disturbances from outside do not impact the essential variables of the system. Ashby noted:

An essential feature of the good regulator is that it blocks the flow of variety from disturbances to essential variables.

J. Achterbergh and D. Vriens expand this further:

Regulators block variety flowing from disturbances to essential variables. The more variety they block, the more effective the regulator. The most effective regulator is the one that blocks all the variety flowing from disturbances to essential variables… We can now also define regulation as the activity performed by the regulator. That is, regulation is “blocking the flow of variety from disturbances to essential variables.” If the more general description of essential variables is used (i.e., those variables that must be kept within limits to achieve some goal) then the purpose of regulation is that it enables the realization of this goal. If the goal is the survival of some concrete system, then the purpose of regulation is trying to keep the values of its essential variables within the limits needed for survival, in spite of the values of disturbances.

This is a good place to introduce the main law of Cybernetics – the law of requisite variety (LRV). LRV is the brainchild of Ross Ashby, the most prolific thinker and pioneer of Cybernetics. LRV states that only variety can absorb variety. Here variety is the number of possible states. For example, a light switch has a variety of two – ON or OFF. If the user just wants the light to be turned on or off, then the light switch can meet that variety. However, if the user wants the light to be dimmed down or up, then the situation calls for a lot more variety than two. Here, a light switch with a variety of two cannot absorb the variety “thrown” at it. However, a dimmer switch with an indefinite amount of variety can achieve this.

Ashby was inspired by Claude Shannon’s tenth theorem. There is an upper limit for the amount of variety the regulator can absorb. The controller will need to find ways to attenuate variety (filter out unwanted variety thrown at the system) and amplify internal variety such that the requisite variety is achieved. A simple example of attenuating variety is the big sign on the front of a fast-food place. The customer should not go into the fast-food place and ask to buy a car. Since there is an upper limit to a single regulator, the controller has to use multiple regulators linked to achieve amplification of variety. The fast-food place can use more employees during rush-hour to meet with the extra variety thrown at it. This is an example of amplifying variety.

Ashby talked about two types of regulation. This has been explained as Passive and Active regulation by J. Achterbergh and D. Vriens. Passive regulation does not make any selection. We can state that passive regulation is always working. An easy example to explain this is the shell of a turtle. It does not make any selections. J. Achterbergh and D. Vriens explained this as follows:

In the case of passive regulation there exists a passive block between the disturbances and the essential variables. This passive block, for instance the shell of a turtle, separates the essential variables from a variety of disturbances. It is characteristic of passive regulation that it does not involve selection… the regulator does not select a regulatory move dependent on the occurrence of a possibly disturbing event, for the block is given independent of disturbances. Because no selection is involved, the passive “regulator” does not need information about changes in the state of the essential variable or about disturbances causing such changes to perform its regulatory activity.

Francis Heylighen explained passive regulation as buffering:

 Buffering—at least in the cybernetic sense—is a passive form of regulation: the system dampens or absorbs the disturbances through its sheer bulk of protective material. Examples of buffers are shock absorbers in a car, water reservoirs or holding basins dampening fluctuations in rainfall, and the fur that protects a warm-blooded animal from variations in outside temperature. The advantage is that no energy, knowledge or information is needed for active intervention. The disadvantage is that buffering is not sufficient for reaching goals that are not equilibrium states in themselves, because moving away from equilibrium requires active intervention. For example, while a reservoir makes the flow of water more even, it cannot provide water in regions where it never rains. Similarly, fur alone cannot maintain a mammal body at a temperature higher than the average temperature of the surroundings: that requires active heat production.

Active regulation requires a selection of activity and requires information. J. Achterbergh and D. Vriens explained active regulation as follows:

In the case of active regulation, the regulator needs to select a regulatory move. Dependent on either the occurrence of a change of the state of the essential variable or of a disturbance, the regulator selects the regulatory move to block the flow of variety to the essential variables. Because it has to select a regulatory move, the active regulator either needs information about changes in the state of the essential variable or about the disturbances causing such changes in order to perform its regulatory function.

There are two forms of active regulation – feedforward (cause-controlled) and feedback (error-controlled). In feedforward regulation, the regulator anticipates and acts when it senses the disturbances prior to having any impact on the essential variable. Heylighen explained this as:

In feedforward regulation, the system acts on the disturbance before it has affected the system, in order to prevent a deviation from happening. For example, if you perceive a sudden movement in the vicinity of your face, you will close your eyelids before any projectile can hit it, so as to prevent potential damage to your eyeball. The disadvantage that it is not always possible to act in time, and that the anticipation may turn out to be incorrect, so that the action does not have the desired result. For example, the projectile may not have been directed at your eyes, but at a different part of your face. By shutting your eyes, you make it more difficult to avoid the actual impact.

In feedback regulation, the regulator acts only after the essential variable is impacted.

In feedback regulation, the system neutralizes or compensates the deviation after the disturbance has pushed the system away from its goal, by performing an appropriate repair action. For example, a thermostat compensates for a fall in temperature by switching on the heating, but only after it detected a lower than desired temperature. For effective regulation, it suffices that the feedback is negative—i.e. reducing the deviation—because a sustained sequence of corrections will eventually suppress any deviation. The advantage is that there is no need to rely on a complex, error-prone process of anticipation on the basis of imperfect perceptions: only the direction of the actual deviation has to be sensed. The disadvantage is that the counteraction may come too late, allowing the deviation to cause irreversible damage before it was effectively suppressed.

Ashby viewed feedforward as reacting to threat, and feedback as reacting to disaster. Feedforward control (cause controlled) generally comes from feedback control (error controlled). We should have a somewhat good knowledge of the situation’s behavior and this comes from previous feedback experiences.

In next week’s post, I will look at the extended form of the Law of Requisite Variety. I will finish this post with an example from J. Achterbergh and D. Vriens to further explain the three forms of regulation with an example of a medieval knight:

To illustrate these different modes of regulation, imagine a medieval knight on a battlefield. One of the essential variables might be “pain,” with the norm value “none.” In combat, the knight will encounter many opponents with different weapons all potentially threatening this essential variable. To deal with these disturbances, he might wear suitable armor: a passive block. If a sword hits him nevertheless (e.g., somewhere, not covered by the armor), he might withdraw from the fight, treat his wounds and try to recover: an error-controlled regulatory activity, directed at dealing with the pain. A cause-controlled regulatory activity might be to actively parry the attacks of an opponent, with the effect that these attacks cannot harm him.

Please maintain social distance and wear masks. Stay safe and Always keep on learning…

In case you missed it, my last post was Getting Out of the Dark Room – Staying Curious:

References:

[1] Cybernetic Principles of Aging and Rejuvenation:the buffering-challenging strategy for life extension – Francis Heylighen

[2] Social Systems Conducting Experiments – Jan Achterbergh, Dirk Vriens

2 thoughts on “Notes on Regulation:

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