# More Control of Behavior

**URL:** <http://discourse.iapct.org/t/more-control-of-behavior/7218>\
**Category:** CSG1998\
**Created:** [September 11, 1998, 7:21pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218 "1998-09-11T19:21:01Z")\
**Posts on this page:** 20\
**Page:** 2

<div class="post-metadata">

**Author:** ![Abbott\_Bruce](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/a/eb9ed0/32.png) [@Abbott\_Bruce](http://discourse.iapct.org/u/Abbott_Bruce)\
**Post date:** [September 13, 1998, 5:19pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/21 "1998-09-13T17:19:39Z")

</div>

[From Bruce Abbott (980913.1320 EST)]

> Bruce Gregory (980913.1105 EDT) --

> I think I'll heed Bill's admonition. When it comes to the speed of my car,  
> only I am in a position to control it. The state may have sanctions designed  
> to influence the way I establish the reference levels I choose for my speed,  
> but these sanctions do not constitute control in the sense that PCT  
> describes control.

Are you sure? Here is what Bill said:

> > To define a variable that someone is controlling, you have to define an  
> > input quantity and an output quantity. The input quantity is the physical  
> > situation that is being perceived, and the output quantity is the means by  
> > which the control system has an effect on the input quantity. Disturbances  
> > are independent variables in the environment that also influence the input  
> > quantity.

> > If the person does perceive the input quantity, and does have an effect on  
> > it by acting on the environment, and if the signs are all right and the  
> > loop gain is sufficient, then the person is controlling the input quantity.

Let's see how closely the actual system conforms to these criteria. The  
state legislature and execuitive branch have built a control system for  
motorist speed. It includes an array of sensors (radar-equipped state  
troopers), perceptual signal (the indicated speeds of motorists), a  
reference speed (the posted speed limit, or less), a comparator (the  
troopers again), an error signal (error is nonzero if motorist speed is  
sufficiently above posted speed limit), an output function (the troopers  
again), whose actions tend to bring the input variable (perceived motorist  
speeds) back to reference (posted speed limit or less). It seems to work,  
too (in that most motorists obey the speed limit when they perceive that  
state troopers are monitoring their speeds).

That sounds like a perfectly good control system to me, in that it seems to  
me to meet all of Bill's criteria. If you disagree, please explain where  
and how it fails.

Regards,

Bruce

---

<div class="post-metadata">

**Author:** ![R\_Marken](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/r/8797f3/32.png) [@R\_Marken](http://discourse.iapct.org/u/R_Marken)\
**Post date:** [September 13, 1998, 7:39pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/22 "1998-09-13T19:39:27Z")

</div>

[From Rick Marken (980913.1140)]

Me:

> If the trooper is organized as a control system with respect to  
> a particular environmental variable (like the speed of your  
> car) and if the loop is closed and the loop gain is high enough  
> then control is taking place -- even if the speed of your car  
> matches the trooper's reference for your speed so that the  
> trooper need do no more than sit quietly on his motorcycle to  
> keep the speed of your car at his reference level.

Bruce Gregory (980913.1345 EDT) --

> O.K. If you want to believe in magic, go right ahead. The trooper  
> is \_not\_ organized like a control system with respect to the speed  
> of my car.

If, as you say, the trooper is not organized as a control system  
with respect to the speed of your car, then, indeed, he cannot  
control the speed of your car. You will note that in my statement  
above I said "If the trooper is organized as a control system with  
respect to a particular environmental..." That's IF as in "IF we  
\_assume\_ that the trooper is organized to control speed then we  
can conclude that he is controlling speed even when he is not  
\_acting\_ to change your speed".

You counter my conclusion by changing the assumption; you just  
assume that the trooper is \_not\_ organized as a control system  
with respect to the speed of your car so he cannot be controlling  
the speed of your car. Given the changed assumption, I agree with  
this conclusion. Of course, the trooper is not and cannot be  
controlling your speed if he is not organized as a control system  
with respect to your speed. Note, however, this trooper is not  
going to do anything about your speed \_regardless\_ of how fast  
you drive the car. So if you assume that the trooper is not a  
control system with respect to the speed of your car then have a  
problem explaining why the trooper goes after your if you \_are\_  
breaking the speed limit. The trooper you describe is one who  
will not try to change your speed whether you are going over  
the speed limit or not.

Are you saying, perhaps, that the trooper simply cannot be organized  
as a control system with respect to the speed of your car? That the  
trooper cannot possibly control the speed of your car because that  
would violate some kind of natural law? Is this what you meant to  
imply by your comments about "thought control" and "magical  
thinking"? If so, I can tell you now that there is no such law; the  
trooper can organize him (or her) self as a control system with  
respect to your speed if s/he wants to.

Bruce Gregory (980913.0935 EDT) --

> At the moment I lack the modeling skills needed to convert  
> this story into a working model

Me:

> This seems like a serious shortcoming in a person who says that  
> we can only understand what we can model.

Bruce:

> I have many serious shortcomings. Fortunately magical thinking  
> is not one of them.

I was merely suggesting that you might not have so much difficulty  
with this "control of behavior" issue (revealed by your comment  
about "magical thinking") if you could turn your imaginings into  
a working model. And you can do this with a \_little\_ thought now  
that we have Vensim available.

Best

Rick

> **···**
>
> --
> 
> Richard S. Marken Phone or Fax: 310 474-0313  
> Life Learning Associates e-mail: rmarken@earthlink.net  
> [http://home.earthlink.net/~rmarken/](http://home.earthlink.net/~rmarken/)

---

<div class="post-metadata">

**Author:** ![Bruce\_Gregory](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Bruce\_Gregory](http://discourse.iapct.org/u/Bruce_Gregory)\
**Post date:** [September 13, 1998, 6:50pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/23 "1998-09-13T18:50:31Z")

</div>

[From Bruce Gregory (980913.1450 EDT)]

Bruce Abbott (980913.1320 EST)

> Let's see how closely the actual system conforms to these criteria. The  
> state legislature and executive branch have built a control system for  
> motorist speed.

No, they have designed a system to \_limit\_ a motorist's speed.

> It includes an array of sensors (radar-equipped state  
> troopers), perceptual signal (the indicated speeds of motorists), a  
> reference speed (the posted speed limit, or less), a comparator (the  
> troopers again), an error signal (error is nonzero if motorist speed is  
> sufficiently above posted speed limit), an output function (the troopers  
> again), whose actions tend to bring the input variable (perceived motorist  
> speeds) back to reference (posted speed limit or less). It seems to work,  
> too (in that most motorists obey the speed limit when they perceive that  
> state troopers are monitoring their speeds).
> 
> That sounds like a perfectly good control system to me, in that  
> it seems to  
> me to meet all of Bill's criteria. If you disagree, please explain where  
> and how it fails.

A very interesting idea. I am not sure Bill would like it though, since it  
is a control system that transcends the individuals who make up the society.  
I think it is an analogy. I agree that the individual trooper is a control  
system designed to issue tickets to drivers who are exceeding the posted  
limit by some amount. The troopers, however, are autonomous, their reference  
systems are established by themselves, not by the state legislature or  
governor. Troopers are free to pursue speeders or to ignore them. (If the  
troopers were \_really\_ concerned with limiting the speed of offenders, they  
would follow them to determine if the offenders resumed speeding; this the  
troopers do not, in my experience, do.) If the troopers really want to limit  
the speed of the drivers, I think your rolling roadblock is the only way to  
accomplish this. The other alternative is to install Rick's throttle  
controls in all cars and allow the troopers to really act as systems  
organized to control the speed of cars.

Bruce Gregory

---

<div class="post-metadata">

**Author:** ![Bruce\_Gregory](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Bruce\_Gregory](http://discourse.iapct.org/u/Bruce_Gregory)\
**Post date:** [September 13, 1998, 7:03pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/24 "1998-09-13T19:03:48Z")

</div>

[From Bruce Gregory (980913.1500 EDT)]

Rick Marken (980913.1140)

> Are you saying, perhaps, that the trooper simply cannot be organized  
> as a control system with respect to the speed of your car?

Yes.

> That the  
> trooper cannot possibly control the speed of your car because that  
> would violate some kind of natural law?

No. Just that the trooper lacks a mechanism such as your radio controlled  
throttle system that would allow him to control the speed of my car.

> Is this what you meant to  
> imply by your comments about "thought control" and "magical  
> thinking"? If so, I can tell you now that there is no such law; the  
> trooper can organize him (or her) self as a control system with  
> respect to your speed if s/he wants to.

The only way I see this happening if the trooper turns off the engine of my  
car and tows me at whatever speed he desires. This I agree would allow him  
to control the speed of my car. Otherwise I don't see how this is possible.  
How, for example, can a trooper control my speed to equal 50 mph in a 65 mph  
zone? If he puts his car in front of mine, as some have done, I can, and  
have, simply passed the trooper. A trooper, as \_you\_ pointed out, is  
probably controlling a program for issuing tickets. I have no doubt that  
such organization is possible.

> I was merely suggesting that you might not have so much difficulty  
> with this "control of behavior" issue (revealed by your comment  
> about "magical thinking") if you could turn your imaginings into  
> a working model. And you can do this with a \_little\_ thought now  
> that we have Vensim available.

I would be grateful if \_you\_ would produce such a model since I obviously do  
not understand how it is even organized.

Bruce Gregory

---

<div class="post-metadata">

**Author:** ![R\_Marken](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/r/8797f3/32.png) [@R\_Marken](http://discourse.iapct.org/u/R_Marken)\
**Post date:** [September 13, 1998, 8:48pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/25 "1998-09-13T20:48:48Z")

</div>

[From Rick Marken (980913.1250)]

Me:

> Are you saying, perhaps, that the trooper simply cannot be  
> organized as a control system with respect to the speed of  
> your car?

Bruce Gregory (980913.1500 EDT) --

> Yes.

But this is incorrect. You have already agreed (see below) that  
a trooper \_can\_ control the speed of a car; he can do it in what  
you call the "Marken-Abbott fashion" (in the way the controllee's  
output is controlled in Bruce Abbott's Vensim model).

Me:

> [Are you saying] That the trooper cannot possibly control the  
> speed of your car because that would violate some kind of  
> natural law?

You:

> No. Just that the trooper lacks a mechanism such as your radio  
> controlled throttle system that would allow him to control the  
> speed of my car.

But this is only a technical difficulty. My radio controlled  
throttle system is not currently in used (thank goodness). I  
only mentioned it because you had said:

> Until I see a model of a trooper controlling the speed of my  
> car without blocking the road ahead of me in the Marken-Abbott  
> fashion I will assume that it is not possible and will do my  
> best to ignore claims to the contrary.

In other words, you wanted to see a model of a system (trooper)  
that controls your speed directly. So I provided a model that  
does this. In fact, real troopers can control speed directly  
without using the Marken-Abbott technique (which works only  
if the driver is controlling for distance from the trooper) \_or\_  
the radio controlled accelerator lever. In high speed chases  
(where the trooper's goal is clearly to control the chasee's  
speed) the trooper can follow the chasee until he runs out of  
gas, until his tires are shot out or until other cops physically  
obstruct his path with some kind of barrier (like another car).  
Real troopers can and sometimes \_will\_ directly control the speed  
of your car.

> The only way I see this [control of my speed] happening [is] if  
> the trooper turns off the engine of my car and tows me at whatever  
> speed he desires. This I agree would allow him to control the  
> speed of my car.

There you go!

> How, for example, can a trooper control my speed to equal 50 mph  
> in a 65 mph zone?

The fact that the controller can't keep the controlled variable  
in all of its possible states doesn't mean that the controller  
is not controlling. I can't get my Geo to go 130 mph on the  
straightaway (I could if it were a Mercedes) but I can control  
its speed. The police in the car chase can only keep the chasee's  
car speed in two states: 0 mph or\>0 mph but they are still  
controlling car speed.

> I would be grateful if \_you\_ would produce such a model since I  
> obviously do not understand how it is even organized.

Ok. But I can't learn PCT for you.

Best

Rick

> **···**
>
> --  
> Richard S. Marken Phone or Fax: 310 474-0313  
> Life Learning Associates e-mail: rmarken@earthlink.net  
> [http://home.earthlink.net/~rmarken/](http://home.earthlink.net/~rmarken/)

---

<div class="post-metadata">

**Author:** ![Abbott\_Bruce](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/a/eb9ed0/32.png) [@Abbott\_Bruce](http://discourse.iapct.org/u/Abbott_Bruce)\
**Post date:** [September 13, 1998, 6:50pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/26 "1998-09-13T18:50:56Z")

</div>

[From Bruce Abbott (980913.1550 EST)]

> Bruce Gregory (980913.1450 EDT) --

> > Bruce Abbott (980913.1320 EST)

> > Let's see how closely the actual system conforms to these criteria. The  
> > state legislature and executive branch have built a control system for  
> > motorist speed.

> No, they have designed a system to \_limit\_ a motorist's speed.

They have designed a \_control\_ system to limit a motorist's speed.

> > That sounds like a perfectly good control system to me, in that  
> > it seems to  
> > me to meet all of Bill's criteria. If you disagree, please explain where  
> > and how it fails.

> A very interesting idea. I am not sure Bill would like it though, since it  
> is a control system that transcends the individuals who make up the society.  
> I think it is an analogy.

If it has all the elements of a control system, connected up in the right  
way, and behaving as a control system behaves, it is the real thing. This  
has all right parts, connected up in the right way, and acts to restore the  
controlled variable to its reference range when that variable rises above  
it. It's a real control system, not merely analogous to one.

> I agree that the individual trooper is a control  
> system designed to issue tickets to drivers who are exceeding the posted  
> limit by some amount.

If the intent of the legislature in designing this system and having it  
implemented was not to limit the speeds of motorists, then it is hard to  
understand why the troopers have been instructed to issue tickets to  
speeders (unless this is just a pretext for relieving the motorists of their  
money so as to enrich the government!). Of course, the individual trooper  
may only be controlling the truth-status of "speeders get tickets,  
nonspeeders do not." Nevertheless, the legislature and the governor have  
set the trooper to this task because they assume that these actions on the  
part of the trooper will tend to bring motorists' speeds down to values not  
exceeding the speed limit.

> The troopers, however, are autonomous, their reference  
> systems are established by themselves, not by the state legislature or  
> governor.

Autonomous, yes. Independent of outside influence, no. How else can you  
can explain why so many autonomous control systems (state troopers) decide  
to go out there and ticket speeders, just as the governor and the  
legislature want them to?

Regards,

Bruce

---

<div class="post-metadata">

**Author:** ![Bruce\_Gregory](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Bruce\_Gregory](http://discourse.iapct.org/u/Bruce_Gregory)\
**Post date:** [September 13, 1998, 8:53pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/27 "1998-09-13T20:53:11Z")

</div>

[From Bruce Gregory (980913.1650 EDT)]

Rick Marken (980913.1250)

> Me:
> 
> \> Are you saying, perhaps, that the trooper simply cannot be  
> \> organized as a control system with respect to the speed of  
> \> your car?
> 
> Bruce Gregory (980913.1500 EDT) --
> 
> \> Yes.
> 
> But this is incorrect. You have already agreed (see below) that  
> a trooper \_can\_ control the speed of a car; he can do it in what  
> you call the "Marken-Abbott fashion" (in the way the controllee's  
> output is controlled in Bruce Abbott's Vensim model).

I was under the mistaken assumption that we were talking about whether or  
not troopers \_do\_ control the speed of my car on the turnpike. Apparently we  
were talking about how troopers conceivably \_might\_ control the speed of my  
car. Yes, troopers conceivably might do this, although they have not been  
known to do so.

> In other words, you wanted to see a model of a system (trooper)  
> that controls your speed directly. So I provided a model that  
> does this. In fact, real troopers can control speed directly  
> without using the Marken-Abbott technique (which works only  
> if the driver is controlling for distance from the trooper) \_or\_  
> the radio controlled accelerator lever. In high speed chases  
> (where the trooper's goal is clearly to control the chasee's  
> speed) the trooper can follow the chasee until he runs out of  
> gas, until his tires are shot out or until other cops physically  
> obstruct his path with some kind of barrier (like another car).  
> Real troopers can and sometimes \_will\_ directly control the speed  
> of your car.

Look at it another way. I can control the behavior of a trooper simply by  
stepping on the gas as I approach him. I can cause the trooper to turn on  
his lights and siren and to follow me! I do this by disturbing a perception  
that he is controlling ala Abbott. Fair enough?

> Ok. But I can't learn PCT for you.

See my above application of the Abbott model. Does this demonstrate an  
understanding of PCT?

Bruce Gregory

---

<div class="post-metadata">

**Author:** ![Bruce\_Gregory](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Bruce\_Gregory](http://discourse.iapct.org/u/Bruce_Gregory)\
**Post date:** [September 13, 1998, 10:03pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/28 "1998-09-13T22:03:20Z")

</div>

[From Bruce Gregory (980913.1800 EDT)]

Bruce Abbott (980913.1550 EST)

> If it has all the elements of a control system, connected up in the right  
> way, and behaving as a control system behaves, it is the real thing. This  
> has all right parts, connected up in the right way, and acts to  
> restore the  
> controlled variable to its reference range when that variable rises above  
> it. It's a real control system, not merely analogous to one.

True, so long as the reference speed is in the trooper's head and not simply  
posted on the highway. As I noted, it results in tickets being given. It is  
not clear that it restores the controlled variable to its reference range. I  
still observe speeders even though tickets are being given. In fact, the  
trooper who is writing a ticket is unlikely to pursue you if you speed up  
after you pass him by. A best people slow down for a mile or two after they  
see a ticket being issued. Some, as I say, speed up.

> If the intent of the legislature in designing this system and having it  
> implemented was not to limit the speeds of motorists, then it is hard to  
> understand why the troopers have been instructed to issue tickets to  
> speeders (unless this is just a pretext for relieving the  
> motorists of their  
> money so as to enrich the government!). Of course, the individual trooper  
> may only be controlling the truth-status of "speeders get tickets,  
> nonspeeders do not." Nevertheless, the legislature and the governor have  
> set the trooper to this task because they assume that these  
> actions on the  
> part of the trooper will tend to bring motorists' speeds down to  
> values not  
> exceeding the speed limit.

True, but intentions of legislators are not relevant to the operation of the  
control system. Prohibition was passed with the intention of stopping the  
consumption of alcohol. It didn't.

> \>The troopers, however, are autonomous, their reference  
> \>systems are established by themselves, not by the state legislature or  
> \>governor.
> 
> Autonomous, yes. Independent of outside influence, no. How else can you  
> can explain why so many autonomous control systems (state troopers) decide  
> to go out there and ticket speeders, just as the governor and the  
> legislature want them to?

I never claimed they were independent of outside influence. If they have a  
quota for tickets, and they are not meeting it, they will probably set their  
reference speed closer and closer to the posted limit.

Bruce Gregory

---

<div class="post-metadata">

**Author:** ![R\_Marken](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/r/8797f3/32.png) [@R\_Marken](http://discourse.iapct.org/u/R_Marken)\
**Post date:** [September 13, 1998, 11:56pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/29 "1998-09-13T23:56:28Z")

</div>

[From Rick Marken (980913.1600)]

Bruce Gregory (980913.1650 EDT) --

> Yes, troopers conceivably might do this [control the speed  
> of cars], although they have not been known to do so.

Well, that's progress.

> Look at it another way. I can control the behavior of a trooper  
> simply by stepping on the gas as I approach him. I can cause the  
> trooper to turn on his lights and siren and to follow me! I do  
> this by disturbing a perception that he is controlling ala Abbott.  
> Fair enough?

Right. You can control a variable (the lights and siren being on  
or off) the trooper is using to control a variable he is  
controlling (like the state of the relationship between your  
speed and your receipt of a ticket) if you can disturb this  
variable (disturb the state of the relationship between your  
speed and your receipt of a ticket).

> Does this demonstrate an understanding of PCT?

Sure. But it would have helped if you had described the  
\_variables\_ you think you and the trooper are controlling  
and how you each control these variables.

Bruce Gregory (980913.1750 EDT) --

> In my house, the thermostat is set to 65 F. During the summer,  
> the temperature in the house never drops below 70 F. Is the  
> thermostat controlling the temperature?

What do you think? Your answer will be another indication of how  
well you understand control theory.

Best

Rick

> **···**
>
> --  
> Richard S. Marken Phone or Fax: 310 474-0313  
> Life Learning Associates e-mail: rmarken@earthlink.net  
> [http://home.earthlink.net/~rmarken/](http://home.earthlink.net/~rmarken/)

---

<div class="post-metadata">

**Author:** ![Bruce\_Gregory](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Bruce\_Gregory](http://discourse.iapct.org/u/Bruce_Gregory)\
**Post date:** [September 13, 1998, 11:02pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/30 "1998-09-13T23:02:00Z")

</div>

[From Bruce Gregory (980913.1900 EDT)]

Bill Powers (980913.0732 MDT)

> Also, it is good to remember, now and then, that people do not control  
> things, they control variables. So one person does not control another  
> person, any more a person controls a car.

When I am driving on the turnpike, the speed of my car can be modeled by a  
simple control loop that includes a reference for 70 mph. There is no need  
to introduce the idea that my speed is being controlled, or even effected,  
by the presence or absence of a state trooper. Why then introduce the notion  
that my speed is being controlled by the trooper? This addition seems  
totally gratuitous and does not improve one iota your ability to predict the  
speed of the car.

Bruce Gregory

---

<div class="post-metadata">

**Author:** ![Bruce\_Gregory](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Bruce\_Gregory](http://discourse.iapct.org/u/Bruce_Gregory)\
**Post date:** [September 13, 1998, 11:14pm UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/31 "1998-09-13T23:14:46Z")

</div>

[From Bruce Gregory (980913.1915 EDT)]

Rick Marken (980913.1600)

> Bruce Gregory (980913.1750 EDT) --
> 
> \> In my house, the thermostat is set to 65 F. During the summer,  
> \> the temperature in the house never drops below 70 F. Is the  
> \> thermostat controlling the temperature?
> 
> What do you think? Your answer will be another indication of how  
> well you understand control theory.

In my view the question is, what are we trying to model? If we are trying to  
model the temperature of the house, there is no need to introduce the  
thermostat and the furnace into the model. To say that the thermostat is  
controlling the temperature in this case smacks more of belief than it does  
of science. The thermostat and furnace play no role in any model I would put  
forth until they are required to explain the changes in temperature. I  
realize that this must make me a PCT pariah but Occam's razor is too  
important a tool to put aside for reasons of theological purity.

Bruce Gregory

---

<div class="post-metadata">

**Author:** ![Marc\_Abrams5](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/m/f08c70/32.png) [@Marc\_Abrams5](http://discourse.iapct.org/u/Marc_Abrams5)\
**Post date:** [September 14, 1998, 12:46am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/32 "1998-09-14T00:46:52Z")

</div>

> From [Marc Abrams (980913.1948)]

I think each of you ( Bruce G & A and Rick ) are correct.  
The control process entails a number of points where someone  
might try to \_affect\_ our ability to control something. I  
can try to provide a "reference" level for you that \_you\_  
will encorporate \_into\_ your control loop. I believe Rick  
was addressing that. You can try to affect someones actions  
( output ) and have \_that\_ incorporated into your control  
loop. t I believe that is what Bruce Gregory was arguing  
against ( i.e. the ability of \_anyone\_ to \_physically\_  
control the speed of the car beside the driver, except maybe  
for a crazed passenger in the front seat who puts his/her  
foot on the accelerator 🙂 ) The other way that someone  
\_might\_ affect the control process is through qi ( i.e.  
either a disturbance or by somehow changing the action going  
into the qi ( possibly by deceit, or a lie ).

The important thing to remember is that it is the \_TOTALITY\_  
of the loop that matters. Not just one individual part. As  
long as the loop remains \_intact\_ control is going on. So  
someone very well might \_affect\_ and hence cause \_effects\_  
at various points with or without control being "broken".

In working through a few problems and hence the model I will  
be posting to the net I have seen some pretty outrageous  
"examples" of S -\> R Psych modeled in SD. What was crazy was  
how the models \_supported\_ these theories. Well folks,  
models can \_support\_ \_ANY\_ argument. The trick is to  
understand the underlying logic and math to understand \_how\_  
the model was formulated. Pictures ( Diagrams ) just aren't  
enough. Neither are descriptive words. Geesh, I'm becoming a  
real cynic. Thanks Bill 🙂

> > Bruce Gregory (980913.1750 EDT) --
> > 
> > \> In my house, the thermostat is set to 65 F. During the  
> > \> summer, the temperature in the house never drops  
> > \>below 70 F. Is the thermostat controlling the  
> > \>temperature?

Rick asked and said:

> > What do you think? Your answer will be another indication  
> > of how well you understand control theory.

Bruce G's response:

> In my view the question is, what are we trying to model?

Great answer, I agree. The question as originally  
formulated by you is incomplete. Are people in the room?.

> If we are trying to model the temperature of the house,

there \>is no need to introduce the thermostat and the  
furnace into \>the model.

Here I disagree. It might be inappropriate for \_your\_ model  
but maybe not mine. You said "we are trying..." implying  
more then one perspective of the problem.

> To say that the thermostat is controlling the temperature

in \>this case smacks more of belief than it does of science.  
The \>thermostat and furnace play no role in any model I  
would put

> forth until they are required to explain the changes in  
> temperature.

I totally agree and support your right to include and  
exclude variables as \_you\_ see fit, for \_your\_ system  
definition and boundries. As Bill stated, lets establish the  
facts first \_then\_ build the model.

> I realize that this must make me a PCT pariah but Occam's  
> razor is too important a tool to put aside for reasons of  
> theological purity.

I think your argument has more to do with establishing  
\_your\_ system boundaries and components then with PCT and I  
agree with your position on that. I don't understand the  
connection to PCT though.

Marc

---

<div class="post-metadata">

**Author:** ![Abbott\_Bruce](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/a/eb9ed0/32.png) [@Abbott\_Bruce](http://discourse.iapct.org/u/Abbott_Bruce)\
**Post date:** [September 14, 1998, 12:19am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/33 "1998-09-14T00:19:05Z")

</div>

[From Bruce Abbott (980913.2020 EST)]

> Bruce Gregory (980913.1915 EDT) --

> > Bruce Gregory (980913.1750 EDT)

> > In my house, the thermostat is set to 65 F. During the summer,  
> > the temperature in the house never drops below 70 F. Is the  
> > thermostat controlling the temperature?

> In my view the question is, what are we trying to model? If we are trying to  
> model the temperature of the house, there is no need to introduce the  
> thermostat and the furnace into the model. To say that the thermostat is  
> controlling the temperature in this case smacks more of belief than it does  
> of science. The thermostat and furnace play no role in any model I would put  
> forth until they are required to explain the changes in temperature. I  
> realize that this must make me a PCT pariah but Occam's razor is too  
> important a tool to put aside for reasons of theological purity.

In the activity you describe as modeling the temperature of the house, you  
are trying to explain why the variable, "temperature of the house" varies as  
it does. If the furnace never kicks on (because the house temperature never  
falls below set point), then there is no need to bring the house's one-way  
temperature control system into the explanation, because the temperature of  
the house is never affected by action resulting from the error between the  
set-point temperature and the actual temperature. Under the conditions you  
describe, the system may as well not be there.

Nevertheless, if the system is operating properly, it is still controlling  
the temperature of the room against excursions below set-point, by  
monitoring the room temperature, comparing it to the reference of 65  
degrees, and being constructed so as to turn on the furnace if the room  
temperature as sensed falls below set point. It is not controlling against  
excursions of room temperature above set point.

In a two-way system (one that takes action to oppose error resulting from  
deviations from reference in either direction) with no deadband, and  
deviation from set-point would be opposed. But control systems can also act  
merely to limit excursions of the controlled variable, with no action being  
called for until deviations from reference exceed a certain value. The  
result is a deadband area within which variations in the input will not  
produce any corrective action. In the case of one-way control systems, no  
corrective action will be taken until the deviation is in a particular  
direction. In the case of your home heating system, deviations above  
set-point are not a cause for corrective action; the system does not control  
against deviations in this direction. Yet it is always controlling against  
deviations below set-point, whether these occur or not.

If you wished to describe the system of variables so that you could  
accurately predict the changes in room temperature under all possible  
conditions, you would need to include the control system in your  
description. If you wished merely to explain the changes in room  
temperature during the summer, when the room temperature never drops below  
70 degrees, you wouldn't, even though the control system designed to keep  
room temperature from falling much below set-point is there and functioning.

Regards,

Bruce

---

<div class="post-metadata">

**Author:** ![Bill\_Powers1](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/8e7dd6/32.png) [@Bill\_Powers1](http://discourse.iapct.org/u/Bill_Powers1)\
**Post date:** [September 14, 1998, 2:39am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/34 "1998-09-14T02:39:30Z")

</div>

[From Bill Powers (980913.2036 MDT)]

Rick Marken (980913.1000)--

> Bruce Gregory (980913.1108 EDT)--
> 
> > Thanks, Bill.
> 
> I'm glad you liked it. If you subtitute "trooper" for "person"  
> and "speed of your car" for "input quantity" you will see that  
> Bill is saying just what Bruce Abbott and I have been saying: that,  
> if the signs are all right and the loop gain is sufficient, then  
> the trooper is controlling the speed of your car when the speed  
> of your car is the controlled input variable.

Can't we just transcend this stupid example and go on to something else? I  
couldn't care less who was right or wrong.

---

<div class="post-metadata">

**Author:** ![Bill\_Powers1](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/8e7dd6/32.png) [@Bill\_Powers1](http://discourse.iapct.org/u/Bill_Powers1)\
**Post date:** [September 14, 1998, 2:49am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/35 "1998-09-14T02:49:23Z")

</div>

[From Bill Powers (980913.2043 MDT)]

Bruce Abbott (980913.1320 EST)--

> Let's see how closely the actual system conforms to these criteria. The  
> state legislature and execuitive branch have built a control system for  
> motorist speed. It includes an array of sensors (radar-equipped state  
> troopers), perceptual signal (the indicated speeds of motorists), a  
> reference speed (the posted speed limit, or less), a comparator (the  
> troopers again), an error signal (error is nonzero if motorist speed is  
> sufficiently above posted speed limit), an output function (the troopers  
> again), whose actions tend to bring the input variable (perceived motorist  
> speeds) back to reference (posted speed limit or less). It seems to work,  
> too (in that most motorists obey the speed limit when they perceive that  
> state troopers are monitoring their speeds).
> 
> That sounds like a perfectly good control system to me ...

I see only one problem with it: it is not designed to perceive YOUR speed.  
As you say, it is set up to perceive "motorists'" speed. The Department of  
Transportation does not receive a report that Bruce Abbott was speeding. It  
knows only that motorists drove, on I-95, at an average speed of 82 mph,  
and that 1,255 speeding citations were issued from April 1 to May 1. While  
your own performance contributed to that average speed, it did so only to a  
minute degree; the loop gain must have been extremely low.

There is some leeway in deciding just how much loop gain there has to be to  
permit us to identify a control system, but I suspect that the threshold  
gain will be something more than 0.001.

Best,

Bill P.

---

<div class="post-metadata">

**Author:** ![Bill\_Powers1](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/8e7dd6/32.png) [@Bill\_Powers1](http://discourse.iapct.org/u/Bill_Powers1)\
**Post date:** [September 14, 1998, 3:15am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/36 "1998-09-14T03:15:43Z")

</div>

[From Bill Powers (980913.1903 MDT)]

Bruce Gregory (980913.1900 EDT)--

> When I am driving on the turnpike, the speed of my car can be modeled by a  
> simple control loop that includes a reference for 70 mph. There is no need  
> to introduce the idea that my speed is being controlled, or even effected,  
> by the presence or absence of a state trooper. Why then introduce the notion  
> that my speed is being controlled by the trooper? This addition seems  
> totally gratuitous and does not improve one iota your ability to predict the  
> speed of the car.

Why do you set the reference for your speed at 70 mph? This setting is the  
net action of all the higher-level control systems on whose perceptions  
speed has some influence. One of them might be "I can't afford to get  
another speeding ticket." When you can't see any troopers ahead or behind,  
or lurking behind road signs, or bleeping your radar detector, you zoom up  
to your chosen speed of 70 mph because you imagine no chance of being  
stopped, and experience no error with respect to getting a speeding ticket.  
But if you spot a trooper ahead, this produces a disturbance of that  
control system, which you counteract by resetting your speed reference  
signal to 55 mph (the local limit). As a result, of course, the car slows  
to 55 mph, and your perceived danger of getting a ticket drops to zero. So  
YOU are controlling the likelihood of getting a ticket by reducing your  
reference level for speed, and THE TROOPER, by displaying himself along the  
road, is controlling your speed by (he assumes) disturbing your perception  
of the likelihood of getting a ticket. Thus each of you controls what  
matters most to him without preventing the other from doing the same.

There are other assumptions about the nature of the controlled variables  
that might lead to different outcomes.

Best,

Bill P.

---

<div class="post-metadata">

**Author:** ![R\_Marken](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/r/8797f3/32.png) [@R\_Marken](http://discourse.iapct.org/u/R_Marken)\
**Post date:** [September 14, 1998, 4:28am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/37 "1998-09-14T04:28:44Z")

</div>

[From Rick Marken (980913.2030)]

Bruce Gregory (980913.1750 EDT) --

> In my house, the thermostat is set to 65 F. During the summer,  
> the temperature in the house never drops below 70 F. Is the  
> thermostat controlling the temperature?

Rick Marken (980913.1600)

> What do you think? Your answer will be another indication of how  
> well you understand control theory.

Bruce Gregory (980913.1915 EDT)

> In my view the question is, what are we trying to model? If we  
> are trying to model the temperature of the house, there is no  
> need to introduce the thermostat and the furnace into the model.  
> To say that the thermostat is controlling the temperature in  
> this case smacks more of belief than it does of science. The  
> thermostat and furnace play no role in any model I would put forth  
> until they are required to explain the changes in temperature.\

Compare your answer to the correct one:

Bill Powers (980913.2056 MDT)

> Yes.

See how much simpler things get when you understand control  
theory.

Best

Rick

> **···**
>
> --
> 
> Richard S. Marken Phone or Fax: 310 474-0313  
> Life Learning Associates e-mail: rmarken@earthlink.net  
> [http://home.earthlink.net/~rmarken/](http://home.earthlink.net/~rmarken/)

---

<div class="post-metadata">

**Author:** ![Bill\_Powers1](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/8e7dd6/32.png) [@Bill\_Powers1](http://discourse.iapct.org/u/Bill_Powers1)\
**Post date:** [September 14, 1998, 3:26am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/38 "1998-09-14T03:26:45Z")

</div>

[From Bill Powers (980913.2117 MDT)]

Bruce Gregory (980913.1915 EDT)--

> In my view the question is, what are we trying to model? If we are trying to  
> model the temperature of the house, there is no need to introduce the  
> thermostat and the furnace into the model. To say that the thermostat is  
> controlling the temperature in this case smacks more of belief than it does  
> of science.

In particular, we are trying to devise a model that will account for the  
behavior of the house's temperature over time, given that the furnace is  
going on and off, people are walking in and out of doors and opening and  
closing windows, and winds of varying temperatures and sun and cloud  
phenomena are changing the heat losses and gains through the walls of the  
house. What we observe is that the net effect of all the heat losses and  
gains through doors, windows, and walls just happens to be offset by  
variations in the on-time of the furnace, so that the temperature near a  
small box on the wall stays remarkably close to 70 degrees F. And we also  
observe that after a person goes to the box and fiddles with it, all the  
same relationships go on happening, but the temperature is now constant at  
65 degrees F.

This is the phenomenon for which we need a model.

> I realize that this must make me a PCT pariah but Occam's razor is too  
> important a tool to put aside for reasons of theological purity.

And it is too sharp for us to encourage its use by the unskilled.

Best,

Bill P.

---

<div class="post-metadata">

**Author:** ![Bruce\_Gregory](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Bruce\_Gregory](http://discourse.iapct.org/u/Bruce_Gregory)\
**Post date:** [September 14, 1998, 10:37am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/39 "1998-09-14T10:37:31Z")

</div>

[From Bruce Gregory (980914.0631 EDT)]

Rick Marken (980913.2030)]

> See how much simpler things get when you understand control  
> theory.

Indeed. Almost as Einstein said, "A pillow on which true believers rest  
their heads so their sleep is not disturbed."

Bruce Gregory

---

<div class="post-metadata">

**Author:** ![Bruce\_Gregory](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/4bbf92/32.png) [@Bruce\_Gregory](http://discourse.iapct.org/u/Bruce_Gregory)\
**Post date:** [September 14, 1998, 10:37am UTC](http://discourse.iapct.org/t/more-control-of-behavior/7218/40 "1998-09-14T10:37:33Z")

</div>

[From Bruce Gregory (980914.0633 EDT)]

Bill Powers (980913.1903 MDT)

> So  
> YOU are controlling the likelihood of getting a ticket by reducing your  
> reference level for speed, and THE TROOPER, by displaying himself  
> along the  
> road, is controlling your speed by (he assumes) disturbing your perception  
> of the likelihood of getting a ticket. Thus each of you controls what  
> matters most to him without preventing the other from doing the same.
> 
> There are other assumptions about the nature of the controlled variables  
> that might lead to different outcomes.

I'll accept that as the last word.

Bruce Gregory

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