From [Marc Abrams (2005.06.29.0103)]

Just a clarification here. I am ‘on the side’ of PCT. I believe in the concept I do not believe in the way Bill has implemented, or structured it. I am not on the side of Bill Powers, just PCT.

I have no final theory or answers, but I am exploring as many possible avenues as possible, minus two key ingredients it seems.

Powers’ paranoia and smugness. But judging from his last rant, maybe he’s not quite as smug as he would like you to believe. His paranoia is self evident.




I thought I'd raise that its a long time since I have seen mention of any
new applied research on PCT. By applied I'm I mean research with actual

PCT has a lot to offer as a pure theory, but also some of the previous
applied work has been great. Has anyone got any applied research they have
recently done?

PCT, whether people believe it or not, seems like a neat framework through
which to research. There also seems enough of it that people agree on for
applied research to occur.

Cheers Rohan


At 02:00 AM 3/07/2003 -0700, you wrote:

From [ Marc Abrams (2003.07.03.0039) ]

> [From Rick Marken (2003.07.02.2000)]

> If you don't have B:CP a paperback version should be available soon.

If it does I would strongly recommend that he re-write this part of the
book. It's showing it's age.

> I'll answer that question the way you answer my questions: by pointing you
to a
> book, but in this case a book that I presume you have on hand, _Behavior:
> control of perception _ (B:CP) by William T. Powers.

Got it right here.

>Your first question is answered on p. 83, in Figure 7.1. Actually, the loop
shown there goes through
> the spinal cord, not the brain, but as you will see, it works the same in
the brain (cortex, cerebellum, etc).

Sure, brain, spinal column, liver, kidney, what difference does it make, you
know what he's talking about.

> The Figure shows that the perceptual signal in this is carried by sensory
nerve impulses.

"THE" perceptual signal? One perception = one signal?, Do you actually mean
_one_ signal? What are 'nerve impulses'? Is that the oscillation of the
interneurons or neurons?

What happened to the chemical ions in the neurons? Do they play a part in
synaptic actions and neuronal communication? Exactly where in B:CP should I
find these answers?

> The reference signal is carried by efferent nerve impulse,

Did you know that many neurons are _bi-directional_? How do you know the
'reference signal' ( again, only one signal? ) is efferent? I know, Bill
told you so in B:CP. Seems reasonable. Where does this 'reference' signal
come from? Don't tell me from the level above. Again you do not mention the
chemical component in intercellular communication. Where do you think the
'electrical impulses' come from?

>the reference efferent neurons in this case descending down the spinal

Where did they originate? These of course being 'motor neurons' right?

> The comparison itself is done by the cell body of a spinal motor neuron
(which I believe makes up the motor ganglia next to the spinal cord).

A ganglia is nothing more then a cyst. What is a 'motor ganglia'. There is a
part of the brain known as the basal ganglion, and in the visual cortex
there are ganglion cells, but I never heard of a 'motor ganglia'. The cell
body does nothing. The cell is a highly specialized and compartmentalized
entity and the cell body simply holds the parts of the cell. The only way
that cells speak to each other is through ionic channels. Most neurons do
act independently. They 'act' in 'patterns'. Might I suggest _I of the
Vortex_ by Rodolfo Linas 2001 MIT Press. Dr. Llinas is the Chairman of the
Physiology and Neuroscience Department at NYU's Medical School here in NYC.
Either that or look for the Cliff notes in your nearest book store.

>The comparison (an approximate subtraction) is the result of the
simultaneous inhibitory effects of the sensory synapse and excitatory
effects of
> the efferent synapse on the firing rate of the spinal motor neuron itself,

Huh? You mean _all_ sensory inputs are 'inhibitory' and _all_ motor outpouts
are 'excitatory'? How can a synapse be efferent? A synapse is nothing more
then a cleft between two neurons. And finally, what is a 'firing rate'? What
gets 'fired' from one cell to another? This is real bad. Not only is it
totally wrong, but it makes the rest of the model, which has some
_excellent_ properties, look like ^%#&^%.

>which carries the error signal as neural impulses. This error signal enters
the environment, a muscle, at the motor end plates, causing the muscle to >
contract in proportion to the rate of firing of the spinal motor neuron.

On and on you go. What the hell is an 'error' signal? Is it a special type
of coded transmission between cells? How would you know an 'error' signal
from a 'reference' signal?

>The degree of muscle tension (which also depends on any loads on the limb
to which the muscle is attached) is sensed by
> the Golgi tendon receptor (in the tendon that connects muscle to bone) .

How does the receptor 'sense' the weight?

> Tension on the Golgi receptor causes neural firing in the sensory nerve,
> rate of firing being a perceptual representation of the tension on the

This sounds 'wonderful'. Where is the feedback and control? I just see
motor output. What if the receptor 'senses' wrong? How does the 'Golgi
Receptor' adjust?

> A more thorough picture of the parts of the brain and spinal cord that are
> thought to be involved in three lower levels of the hierarchy is shown on
> 117, Figure 9.1.

Very nice, but not quite accurate.

> The first order control systems are in the spinal cord, the second order
systems are in the cerebellum and the third order systems are in
> the cerebellar cortex.

Says who? Outdated, and old ideas about the brain had it divided
'functionally', that is, certain parts of the brain performed certain
functions. The cerebellum was thought to be involved with our motor (
muscle ) skills. It has been learned that the pure 'functional' view of the
brain is not accurate. Lots of things happen in all parts of the brain. Yes,
certain parts of the brain seem to have more of one type of activity then
another, but things pretty much get spread around. In one recent experiment,
they found that blind people were utilizing there 'visual cortex' area (
that's in the back of the brain ) for verbal memory. The pure functional
model, although still adhered to by some, is out of fashion. Of course this
is all very sophisticated hand waving. But I'd venture to say that these
people have a lot more to work with then Bill had 50 years ago. Brain
research has come a long way in the past 5-10 years, and it's getting better
and better.

> If you don't have B:CP a paperback version should be available soon.

I think I'll wait for the movie.


[From Rick Marken (2003.07.03.0805)]

Rohan Lulham wrote:

I thought I'd raise that its a long time since I have seen mention of any
new applied research on PCT. By applied I'm I mean research with actual

Three of the planned presentations at the CSG conference are on applied topics:

      Richard Thurman "Developing learning environments from a PCT perspective"
      Gary Cziko "PCT and autonomous second language learning:
      Rick Marken "Error in skilled performance: A control model of

I don't know whether Rich or Gary's stuff is published yet but my paper on
prescribing error will appear in _Ergonomics_ this year.

Best regards



Richard S. Marken, Ph.D.
Senior Behavioral Scientist
The RAND Corporation
PO Box 2138
1700 Main Street
Santa Monica, CA 90407-2138
Tel: 310-393-0411 x7971
Fax: 310-451-7018
E-mail: rmarken@rand.org

From [Marc Abrams (2004.08.20.1102)]

In my last post I referred to PCT as 'Powers Control Theory'. I want to
state categorically that this was not, and is not, meant as a knock or mock
of the work of Bill Powers.

In my judgment calling it 'Perceptual' Control theory gives it an air of a
theory that is the collection of wisdom of any number of contributors over a
period of time. This simply is not the case. In fact any attempt to even
_think_ about potential changes or alterations brings on accusations of
trying to 'steal' his theory or trying to invent a new one which is absolute

As far as I know there is no official theory of PCT other than what was
written over 30 years ago and what has been written in any number of other
places over that same time span all by Powers and what Powers says it is on
any given day. It seems that others have spent a good deal of time trying to
validate _some_ of the claims made by Powers. I'm not sure anyone has
provided any new or additional insights Powers has accepted as adding to his
existing theory except for Cziko's addition of an additional level years
ago. Did Bourbon add anything that Powers did not already believe and know?
Marken, Kenneway? Abbott?

Please inform me.

Who besides Powers decides what is, and is not, part of the theory of PCT?

Maybe when a reviewed journal actually happens the name Perceptual will be a
bit closer to the reality and gain a bit of legitimacy.


'From[Bill Williams 20 August 2004 2:00 PM CST]

From [Marc Abrams (2004.08.20.1102)]

In my last post I referred to PCT as 'Powers Control Theory'. I >want to state categorically that this was not, and is not, meant >as a knock or mock of the work of Bill Powers.

I think perhaps the best way to understand the difficulty Bill Powers faces is to consider what has happened to the efforts which have been made to apply control theory such as Bill Glasser's program, and then the programs that split-off from the Reality Therapy program. Each of these programs has, I believe, come to include significant elective elements. At least in my opinion many, and perhaps all, of these eclective elements has been introduced as a result of a failure of understanding of control theory. Very few people that I have encountered among those applying control in an educational or clinical setting have the sort of educational background that would promote a level of understanding of control theory which would provide an adaquate basis for solving the problems involved. How is this problem to be solved? Well hold on. Let's consider the problems that have been experienced among the active contributors to CSG, and CSGnet. Bill Powers in attempting to cope with some of these problems has alternated between some rather severe criticism of Rick Marken and efforts to patch up ill feelings. If Rick gets PCT wrong so often, and sometimes so badly -- the "giant leaps in the wrong direction." can it be said that there is a body of knowlege here that is inter-subjective in character?

I think the obvious answer is that the extent of such knowledge and practice too for that matter is rather limited. There are problems regarding CSG, CSGnet and associated activities that go beyond the open problems that are evident on the CSGnet--and these evident problems are sufficiently severe and extensive in themselves.

How are the problems being solved? Or, are the problems being solved? In my view, from the perspective of an economist Bill Powers' effort to create an alternative to economic orthodoxy based upon his dad's copy of underconsumptionism is so implausible that your judgement that is no danger is I am sure correct. But, the answer to my question-- How are the problems getting sovlved, is that if Bill Powers understands the problem there is some hope of the problem gettting solved-- if he doesn't understand then the problem isn't likely to be solved. Is this to way to do science? Well, unfortunately it is often the way that science bumps and bangs along.

My answer to the problem is for everyone to buy an osciloscope and some Op-Amps.

Bill Williams

From [Marc Abrams (2005.12.15.2147)]

From the standpoint of detail and what PCT is attempting to explain shouldn’t PCT be considered more appropriately to be in the field of psychophysiology and studied from within that domain?

I ask this because Bill’s vision is that the theory is isomorphic to some as yet unknown physiological correlates. By unknown I mean the specific functions of the control process with biological entities.

I have just skimmed the Handbook of Psychophysiology,2nd edition and I think anyone serious about PCT should take a look at this as well. Chapter 17 in particular which is on feedback systems.

Anyone have any thoughts on this?