Control System Description

[From Bill Powers (2009.04.28.0646 MDT)]

David Goldstein (2009.04.27.18:00 EDT) --

Here is something I wrote. It was inpired by observing my one year old granddaughter, Lilah, trying to eat with a spoon.
It was also inspired by my Friday lunch with Dr. David London, a colleague, as I tried to explain the concept of control.

Let's reorganize this thread a little. I think examples like yours are great, but I'm really looking for ways of translating from PCT into ordinary language and vice versa. Your examples and those offered by others are good, but let's try to tie them to teaching PCT.

I gave a list of words to avoid, as a way of forcing attention toward the concepts behind them. But suppose we try setting it up like this: Define each of these terms without using any of the others:

control
disturbance
input quantity
input function
perceptual signal
reference signal
comparator
error signal
output function
output quantity
feedback function

That's the whole loop.

The difficulty with just giving examples is that the listener doesn't know which part of the example is important or what each part is supposed to convey. I think new learners need a little more help than that.

Take the first word, control. How does controlling something differ from reacting to a stimulus or planning an action and then carrying it out? Examples are useful for this -- you can use examples to show the differences. As you develop the explanation you'll have to think of ordinary terms, or use parts of your example, to talk about disturbances and the other terms above without naming them. How would you explain putting food in your mouth as a response to a stimulus? As a planned action? And as a control process?

The list consists of general terms; what you want in your description is an equal level of generality. That is, control isn't just putting food into your mouth, it's any process that .... blah blah blah. You have to try to generalize a little so the particular example doesn't become too central. I guess what I'm saying is that after giving an example, you should pause to generalize it, maybe mentioning a different example and pointing out what is the same in both of them. Putting food in your mouth, threading a needle. Give some guidance about what the important general idea is. You don't want to leave the impression that control works only for eating.

A teacher of expository writing would probably explain what I'm after better than I can. But you're all smart guys out there, you can figure it out.

Best,

Bill P.

About: [Bill Powers (2009.04.28.0646 MDT)]

This is hard. But here it is.

BP: I gave a list of words to avoid, as a way of forcing attention toward the concepts behind them. But suppose we try setting it up like this: Define each of these terms without using any of the others:

DG: control: a person's actions are the means by which the person obtains and keeps actual experiences matching wanted experiences.
disturbance: experiences which are independent of the person's actions.
input quantity: experiences which are the result of the combined effect of experiences which are independent of the person's actions and the impact of the actions of the person on the environment.
input function; brain circuits which translate environmental stimulation into nervous system activity (eyes, ears, etc..)

perceptual signal: nervous system activity in afferent pathways of the nervous system which result from environmental stimulation.

reference signal: nervous system activity which represents what a person wants.

comparator; brain circuits which calculate how close actual experiences are to wanted experiences.

error signal: the difference between actual and wanted experiences.
output function; brain circuits which translate nervous system activity representing the difference between actual and wanted experiences into actions which change the environment.

output quantity; changes in the environment which are the result of a person's actions.

feedback function: changes in experience which are the result of the person's own actions.

···

From: [David Goldstein (2009.04.29.09:13 EDT)]

[From Richard Kennaway (2009.04.29.1520 BST)]

I don't want to butt in on Bill's commentary here, but one thing leapt out at me:

From: [David Goldstein (2009.04.29.09:13 EDT)]
DG: control: a person's actions are the means by which the person obtains and keeps actual experiences matching wanted experiences.
disturbance: experiences which are independent of the person's actions.

We don't experience disturbances.

input quantity: experiences which are the result of the combined effect of experiences which are independent of the person's actions and the impact of the actions of the person on the environment.
input function; brain circuits which translate environmental stimulation into nervous system activity (eyes, ears, etc..)

perceptual signal: nervous system activity in afferent pathways of the nervous system which result from environmental stimulation.

reference signal: nervous system activity which represents what a person wants.

comparator; brain circuits which calculate how close actual experiences are to wanted experiences.

error signal: the difference between actual and wanted experiences.
output function; brain circuits which translate nervous system activity representing the difference between actual and wanted experiences into actions which change the environment.

output quantity; changes in the environment which are the result of a person's actions.

feedback function: changes in experience which are the result of the person's own actions.

The word "experience" is used throughout, but if it isn't just a synonym for "perception", I don't see what work it is doing.

···

--
Richard Kennaway, jrk@cmp.uea.ac.uk, Richard Kennaway
School of Computing Sciences,
University of East Anglia, Norwich NR4 7TJ, U.K.

About: [Richard Kennaway (2009.04.29.1520 BST)]

RK: We don't experience disturbances.

OK. Do we experience the effect of disturbances?

RK: The word "experience" is used throughout, but if it isn't just a synonym for "perception", I don't see what work it is doing.

DG: Yes, the assignment was to use ordinary language words. I think that experience comes close to the meaning of perception and that people undertand it.

···

From: [David Goldstein (2009.04.29.11:18)]

----- Original Message ----- From: "Richard Kennaway" <jrk@CMP.UEA.AC.UK>
To: <CSGNET@LISTSERV.ILLINOIS.EDU>
Sent: Wednesday, April 29, 2009 10:25 AM
Subject: Re: Control System Description

[From Richard Kennaway (2009.04.29.1520 BST)]

I don't want to butt in on Bill's commentary here, but one thing leapt out at me:

From: [David Goldstein (2009.04.29.09:13 EDT)]
DG: control: a person's actions are the means by which the person obtains and keeps actual experiences matching wanted experiences.
disturbance: experiences which are independent of the person's actions.

We don't experience disturbances.

input quantity: experiences which are the result of the combined effect of experiences which are independent of the person's actions and the impact of the actions of the person on the environment.
input function; brain circuits which translate environmental stimulation into nervous system activity (eyes, ears, etc..)

perceptual signal: nervous system activity in afferent pathways of the nervous system which result from environmental stimulation.

reference signal: nervous system activity which represents what a person wants.

comparator; brain circuits which calculate how close actual experiences are to wanted experiences.

error signal: the difference between actual and wanted experiences.
output function; brain circuits which translate nervous system activity representing the difference between actual and wanted experiences into actions which change the environment.

output quantity; changes in the environment which are the result of a person's actions.

feedback function: changes in experience which are the result of the person's own actions.

The word "experience" is used throughout, but if it isn't just a synonym for "perception", I don't see what work it is doing.

--
Richard Kennaway, jrk@cmp.uea.ac.uk, Richard Kennaway
School of Computing Sciences,
University of East Anglia, Norwich NR4 7TJ, U.K.

[From Rick Marken (2009.04.29.0900)]

Richard Kennaway (2009.04.29.1520 BST)]

The word "experience" is used throughout, but if it isn't just a synonym for
"perception", I don't see what work it is doing.

Oh, crap. That's the word I was going to use (not "crap";
"experience"). Now what? Maybe I'll just have to go with "environment"
despite the epistemological risks;-)

Best

Rick

···

--
Richard S. Marken PhD
rsmarken@gmail.com

[From Dick Robertson, 2009.04.29.11:43CDT]

I’d like to try my hand at this one, to see if I’m in the right ballpark.

···

From: [David Goldstein (2009.04.29.11:18)]

RK: We don’t experience disturbances.

OK. Do we experience the effect of disturbances?

I think we might experience/infer effects of disturbances indirectly when we find ourselves needing to make a lot of effort to keep a situation in the condition that we desire. But I don’t think we get any evidence as to what kind of disturbance might be requiring a lot of effort, unless the particular situation is a very narrowly limited one in which --from prior experience-- we know there is only one kind of influence that can effect one’s efforts, like, say, holding one’s cap on in a strong wind.

Best,

Dick R

From [David Goldstein (2009.04.29.07:40 EDT)]

About [Dick Robertson, 2009.04.29.11:43CDT]

DR: I think we might experience/infer effects of disturbances indirectly when we find ourselves needing to make a lot of effort to keep a situation in the condition that we desire.

DG: Some more discussion about the concept of disturbance.

Let’s take the case of an adult person who is standing. The person’s actions make a contribution to the result. If the person were standing in a lake where the water went up to the shoulders, the person’s actions would make a different contribution. The adult person knows about gravity and buoyancy.

Consider the case of a preschool-aged person. A person this age probably doesn’t know about gravity and buoyancy, yet he/she would be able to control the experience of standing on solid ground or water.

So, in order to control the experiece of standing, one doesn’t need to know what disturbances are acting. One only has the variable of experience which is being controlled.

So, how to define disturbance?

disturbance: All the nonperson influences on the experiencial variable other than the person’s impact on it. If a person is controlling the experiencial variable, the impact of the person will be equal and opposit to the impact of all the disturbances acting on the experiencial variables.

···

----- Original Message -----

From:
Robertson Richard

To: CSGNET@LISTSERV.ILLINOIS.EDU

Sent: Wednesday, April 29, 2009 12:57 PM

Subject: Re: Control System Description

[From Dick Robertson, 2009.04.29.11:43CDT]

I’d like to try my hand at this one, to see if I’m in the right ballpark.

From: [David Goldstein (2009.04.29.11:18)]

RK: We don’t experience disturbances.

OK. Do we experience the effect of disturbances?

I think we might experience/infer effects of disturbances indirectly when we find ourselves needing to make a lot of effort to keep a situation in the condition that we desire. But I don’t think we get any evidence as to what kind of disturbance might be requiring a lot of effort, unless the particular situation is a very narrowly limited one in which --from prior experience-- we know there is only one kind of influence that can effect one’s efforts, like, say, holding one’s cap on in a strong wind.

Best,

Dick R