Side Effects of Control

One of the first papers I published on what is now called PCT (when I still hadn’t mastered the “that-which” distinction, I’m afraid) was about distinguishing intentional from accidental behavior. What I called “accidental” behavior is behavior that is an unintended side effect of intentional behavior, which, of course, is the behavior that is recognized in PCT as control.

I mention this because the topic of “side effects” came up in the recent discussion of the power law of movement. Several times in that discussion I described the power law as an irrelevant side effect of control. While there seemed to be general agreement that the power law is, indeed, a side effect of control, there were objections to my calling it “irrelevant”. The main objection seemed to be that, by calling the power law “irrelevant”, I was saying that it was not worth studying it. And that is not what I meant.

An irrelevant side effect is a side effect of control that is irrelevant to the controlling done by a control system. But that same side effect can be relevant to the extent that it has an effect on the controlling done by another control system. This distinction was discussed on CSGNet back in 1995.

I agree with Bill’s description of the difference between relevant and irrelevant side effects but I would extend the definition of relevant side effects to include effects on another system’s controlled variable in a different organism, not just in the same organism. By this expanded definition the power law is a relevant side effect because it has clearly had an effect on some variable(s) controlled by researchers studying movement production. This might be grist for an interesting PCT-based social psychological study of the controlling done by movement scientists.

Agreed, thanks Rick!

So you agree that I was right all along about the “power law”. It takes a person with a great deal of integrity to do that. You are the Liz Cheney of iapct.discourse. Thanks

Eh? It’s you who has switched from calling it an irrelevant side effect, to a relevant side effect…

No, I have continued to call it an irrelevant side effect since the power law is clearly irrelevant to the process of movement production. Power law researchers have been studying the power law because they think it is relevant to movement production when it actually is not.

I did note that you could also consider it a relevant side effect since a side effect of the power law has been to deceive researchers into thinking it was relevant to understanding the process of movement production. So it is relevant to the controlling done by the researchers who have been studying the power law thinking it was relevant to understanding movement production.

I thought (hoped, actually) you were agreeing with my original post because you understood that the power law was an irrelevant side effect of the controlling involved in movement production but a relevant side effect with respect to the controlling done by the researchers studying the power law.

Is that what you were agreeing with?

Since you haven’t answered I’ll assume the answer is “no”. Which is too bad. I guess I’m still a minority of one.

Sorry, I’m a bit slow on the replies. I think the choice of the definition of ‘irrelevant’ in this example is about subjective priorities and I can therefore see both sides.

Of course you do. But I would be interested in why you think the definition of “irrelevant” (irrelevant side effects, I assume) is about subjective priorities. And why, therefore, it allows you to see both sides.

A lovely suspension bridge of words. Or NIGYYSOB spider web.

Priorities which are not subjective are presumably objective priorities. An evolutionary basis for the distinction is stated Bill Powers (2004.05.23.2026 NMDT) in the thread called ‘Evangelical Control Theory’. Intersubjective agreement is widely regarded as another basis (discussion), at least when the agreeing parties are engaged in a science.

‘Priorities’ are a function of reference values for CVs and loop gain in their control; if you want a lot of perception p it’s a higher priority, and if you want it a lot, i.e. will make efforts to overcome strong disturbances, it’s a higher priority.

Seeing both sides meets F. Scott Fitzgerald’s “test of a first-rate intelligence … the ability to hold two opposed ideas in mind at the same time and still retain the ability to function.” It can be tolerance for cognitive dissonance while working out an internal conflict. It can occur while imagining perceptions from another’s point of view. That is a prerequisite for the Test for Controlled Variables (viz. the subject’s point of view alongside that of the experimenter).

In this exchange, perceptions of ‘movement scientists’ are imagined, with some evidential basis, but not tested.

I’m afraid this doesn’t help me understand why Warren said that the definition of “irrelevant side effects" is about subjective priorities.

The “evidential basis” for what I imagine to be the views of movement scientists (and hangers on like Eetu, Martin, Warren and you) is the extremely strong negative response to the disturbance of my analysis. You guys are definitely controlling for the power law not being an irrelevant side effect of control.

So if the ability to see both sides meets Fitzgerald’s test of a first-rate intelligence, movement scientists don’t pass the test any better than I do.

I doubt you have any evidence for that. All Eetu and I have ever been controlling for (I can’t speak for Warren) is the correct usage of standard mathematics. If your power-law theory had used correct mathematics, I doubt there would ever have been an issue.

Here is the evidence:

My mathematical analysis of the power law is exactly the same as that of Maoz et al. You have only used the “bad math” argument against me, not Maoz et al, which means that their math was not a disturbance to what you are controlling for.

The only difference between my analysis and that of Maoz et al was the conclusion. This is pretty strong evidence that what you really don’t like is my conclusion – that the power law is an irrelevant side effect of control – not my math – that log V = -1/3 log C + 1/3 log D, which is exactly the same as the Maoz math

So it’s pretty clear to me that you are controlling for the power law NOT being an irrelevant side effect of control. What you (and your acolytes) think it is is beyond me.

Could you send a link to the Maoz et al paper? I can’t find it in google scholar. I remember looking at it a while back and not thinking it relevant to the discussion, so I’d like to have another look at it.

Here you go.

I didn’t see a link or an attachment in your reply, Rick, but a search on Maoz in our Discourse interface turned up this Dropbox link to “Noise and the two-thirds power law” in an August 1 post of yours.

It was under “Here”

Grazie mille.

Ah! Reading too fast again. But no harm, and what’s a little redundancy among friends.

You should stick with PCT on this - find controlled variables. The phenomenon is that people slow down in curves in most “natural” movement (“natural” meaning not too slow or too fast). The phenomenon is VERY RELEVANT because any model that purports to explain movement needs to also slow down in curves just like the people do, or not slow down, just like the people do.

The relationship between speed and curvature is either controlled or not, so the procedure should be directly disturbing this relationship and looking for the response from the participants: if they maintain it stable, it might be controlled. If it is not controlled, go for the next hypothesis of what is controlled and repeat the procedure.

Learn the basics of PCT, do some experiments, build a model, then you can understand what is relevant and what is irrelevant.

In principle, if you disturb a side effect there will be no resistance to the disturbance, yes.

How to disturb the speed of movement along a curved path without disturbing control of movement and/or control of curving? I don’t see an obvious way to tease these apart.

That’s assuming that movement and curving are CVs and speed is not.

Or is speed controlled, subject to disturbance due to control of curvature?

Yeah, it is tricky, it took me a few years to get to the bottom of it.

If the relationship between speed and curvature is the controlled variable, then this relationship should stay the same even when you change the one of the variables. Curvature is a spatial variable, pure geometry. Take any random path, you can change the speed as you wish - only if you move VERY SLOWLY. You can draw the letter “O” very, very slowly with a constant speed of 1mm/s at all times. You can draw ANY shape at a constant speed of 1 mm/s.

In that case, the relationship is NO CORRELATION. Constant speed regardless of curvature. I think we can control that even with a direct disturbance like a weight on your hand. Maybe up to a pound or two of mass in the hand.

In the low ranges of speed, we could even go faster in curves and slower in flat parts. Imagine driving a car with 0.1 meter/s in the straight parts and like 1 meter/s in the curves parts. We can change the speed as we wish - even if there is wind, and slopes in the road.

If we are going faster, on average, we have to slow down in curves, and we cannot maintain the same curvature (the same geometric path) with the same relationship to speed as before. We have to slow down in curves to stay on the path. This is what happens in the “natural” movement.