# Help me modeling

**URL:** <http://discourse.iapct.org/t/help-me-modeling/5189>\
**Category:** CSG2000\
**Created:** [November 20, 2000, 7:10pm UTC](http://discourse.iapct.org/t/help-me-modeling/5189 "2000-11-20T19:10:12Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![BJORN\_SIMONSEN](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/8baadc/32.png) [@BJORN\_SIMONSEN](http://discourse.iapct.org/u/BJORN_SIMONSEN)\
**Post date:** [November 20, 2000, 7:10pm UTC](http://discourse.iapct.org/t/help-me-modeling/5189/1 "2000-11-20T19:10:12Z")

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[From Bjoern Simonsen (2000.11.20.2015)]

Can I ask for comments to my simple attached powerSim model of a feed back  
loop. (I guess knowledge about PowerSim is unnecessary. The attached file is  
in MS Word)

The three upper auxiliaries are used to generate a reference signal when  
there is an output quantity or a disturbance.

I let the simulation last 24 hours and I have let there be a disturbance at  
07:00 AM, at 11:00 AM, at 04:00pm and 06:00 PM. (see aux Disturbance in the  
equations)

Bjoern

[PCT model with equations.doc](http://discourse.iapct.org/uploads/short-url/mpf4DpdhoV3dUBTKt1P2TqO0bKr.doc) (72 Bytes)

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**Author:** ![Richard\_Marken2](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/r/edb3f5/32.png) [@Richard\_Marken2](http://discourse.iapct.org/u/Richard_Marken2)\
**Post date:** [November 21, 2000, 3:39am UTC](http://discourse.iapct.org/t/help-me-modeling/5189/2 "2000-11-21T03:39:44Z")

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[From Rick Marken (2000.11.20.1940)]

Bjoern Simonsen (2000.11.20.2015) --

> Can I ask for comments to my simple attached powerSim model  
> of a feed back loop.

It looks OK to me. The only thing that stands out is the ke  
function, which should go between the disturbance and the  
input quantity (controlled variable). But that shouldn't  
affect the behavior of simulation much.

Oh. And I think you might want to change the Comparator  
function to Reference-Input\_function (instead of  
Reference+Input\_function, which should be producing positive feedback).

Also, please be careful about posting your models as attachments.  
For some reason the diagram you posted took up nearly 600 KB in  
the archives.

Best

Rick

> **···**
>
> --
> 
> Richard S. Marken Phone or Fax: 310 474-0313  
> Life Learning Associates e-mail: marken@mindreadings.com  
> mindreadings.com

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**Author:** ![Jeff\_Vancouver2](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/j/b5ac83/32.png) [@Jeff\_Vancouver2](http://discourse.iapct.org/u/Jeff_Vancouver2)\
**Post date:** [November 22, 2000, 3:41pm UTC](http://discourse.iapct.org/t/help-me-modeling/5189/3 "2000-11-22T15:41:22Z")

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[from Jeff Vancouver (2000.11.22.1030)]

Bjoern Simonsen (2000.11.20.2015)]

Why do you make the perception negative (via your input function)? This  
goes to Mark's point about the plus in the comparator. I think you want the  
input function to be positive and the comparator to do the subtraction.  
That way, you do not have negative neural signals and you have the standard  
comparator.

Also, I am not sure the point of the random upper levels auxiliary. It ends  
of an 8 anyway (unless input is 0).

Finally, it is very abstract, what is it for?

For what it is worth.

Jeff

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<div class="post-metadata">

**Author:** ![BJORN\_SIMONSEN](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/b/8baadc/32.png) [@BJORN\_SIMONSEN](http://discourse.iapct.org/u/BJORN_SIMONSEN)\
**Post date:** [November 22, 2000, 9:35pm UTC](http://discourse.iapct.org/t/help-me-modeling/5189/4 "2000-11-22T21:35:07Z")

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[From Bjoern Simonsen(2000.11,22.22:40 GMT+1)]

[From Rick Marken (2000.11.20.1940)]

> Oh. And I think you might want to change the Comparator  
> function to Reference-Input\_function (instead of  
> Reference+Input\_function, which should be producing positive feedback).

Thank you for comments.

My thinking behind that part of the model is B:CP page 62 "The comparator is  
a subtractor. The perceptual signal enters in the excitatory sense (minus  
sign). The resulting "error signal" has a magnitude proportional to the  
algebraic sum of these two neural currents - ..."

I made the Input\_function negative to let it correspond to its excitatory  
sense. Having done that I had to have the comparator function like  
"Reference+Input\_function". If I had the comparator function like  
"Reference - Input\_function" it would be producing positive  
feedback.Wouldn't it?

I am still unsure how to make a simple negative feedback loop in my  
software. But I'll get it. When I am satisfied I'll combine more and more  
loops until I can have a simple model showing e.g. the human pupil contract  
when luminous intensity is changing.

> Also, please be careful about posting your models as attachments.  
> For some reason the diagram you posted took up nearly 600 KB in  
> the archives.

I will.

[From Bruce Abbott (2000.11.21.1700 EST)]  
....................... At present I'm getting posts from

> the CSG-net archives and don't want to download the current 600+ K file if

I

> can avoid it.

You will not get any more 600+ K from me.

[from Jeff Vancouver (2000.11.22.1030)]

> Why do you make the perception negative (via your input function)? This  
> goes to Mark's point about the plus in the comparator. I think you want

the

> input function to be positive and the comparator to do the subtraction.  
> That way, you do not have negative neural signals and you have the standard  
> comparator.

See above

> Also, I am not sure the point of the random upper levels auxiliary. It

ends

> of an 8 anyway (unless input is 0).

My thinking behind that part of the model is still B:CP page 62. "The  
"reference signal" is a neural current having some magnitude. It is assumed  
to be generated elsewhere in the nervous system. ...."

As I understand PCT the Reference is stimulated from different  
Output\_functions from upper levels. Using random upper levels I try to show  
that the reference is stimulated of different intensities coming from  
different upper Output\_functions. But this reference nevertheless gets the  
strength 8. (just a selected number)

I have a problem when input is 0. Then the error will be 8. And when the  
error is 8, the next error will be 0. And so on.  
If the reference is 0 when input is 0, the error also will be 0.  
I lack an explanation how PCT describe the negative feedback loop when input  
is 0.

I still wish comments.

> Finally, it is very abstract, what is it for?

> For what it is worth.

I am describing a theory. That is about what I can't experience, but only  
imagine. Theory is abstract.  
Working with simulating models I discover how little I understand PCT. I run  
into questions I have problems to answer. And sometimes I go to CSG net to  
get help. I know these are simple questions but I'm not sure I yet can  
answer them better myself. But I will.

Bjoern