# The PCT Revolution

**URL:** http://discourse.iapct.org/t/the-pct-revolution/11353
**Category:** CSG1993
**Created:** [March 19, 1993, 5:20pm UTC](http://discourse.iapct.org/t/the-pct-revolution/11353 "1993-03-19T17:20:35Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Marken\_Richard\_S1](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/m/977dab/32.png) [@Marken\_Richard\_S1](http://discourse.iapct.org/u/Marken_Richard_S1)
#### Post date: [March 19, 1993, 5:20pm UTC](http://discourse.iapct.org/t/the-pct-revolution/11353/1 "1993-03-19T17:20:35Z")

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[From Rick Marken (930319.0830)]

Bill Powers (930319.0730) --

> I almost fell for Martin Taylor's explanation, Rick. It's only  
> your persistence that put me back on the track. Martin is a  
> silver-tongued devil.

Thanks for your support; I'm sure that I must seem like an  
uncompromising maniac unwilling to give an inch over a  
seemingly trivial point. But to me, understanding that there  
is no information about (or a usable representation of) the  
disturbance in the perception (or CEV) is the central (revolutionary)  
fact of PCT (with respect to the behavioral sciences). It is the  
fact that PROVES that the input-output model of behavior -- the  
framework within which all work in the behavioral sciences is done--  
is WRONG. PCT even shows why it has seemed like the input-output  
model works -- disturbance resistance; in the process of controlling  
(uninformative) perception, control systems generate outputs that  
counteract disturbances to the controlled perception; if you see the  
disturbance (like a light shined in the eye) then the output (pupil  
size variations) seem to be caused by it. But control systems don't  
really work that way -- when organisms are in a closed negative  
feedback relationship to their own sensory inputs, then (most of)  
these sensory inputs are NOT the cause of outputs; in fact, they  
are controlled by outputs, and this control is not accomplished  
because of anything informative about the sensory inputs themselves.

Note that those aligned against me on this point are people who  
"accept" or at least are sympathetic to the PCT model of behavior  
-- Martin, Allan, Oded, Avery. I'm sure there are many others  
listening who feel the same way "PCT is great but this Marken  
guy is pretty extreme -- imagine, saying that perceptual input  
doesn't contain any information about the disturbance. A guy like  
that just gives PCT a bad name -- what does he expect me to believe,  
that our perceptions don't provide any information about how we  
should deal with the world. I like the idea of control of perception  
and feedback and all that but I don't see why a PCTer would have  
to deny physical reality to try to sell the theory. Having loonies  
like Marken around just gives PCT a bad name".

I (Marken) understand how you feel. All I ask is that those who are  
interested go over all the discussion and try to understand the  
points and the justifications for them. I think you will find  
(especially if you do the relevant demos and the relevant math)  
that crazy Marken is right. There is no compromise on this issue --  
not because I don't want to (I'm all for cooperation) but because I  
am correctly describing the operation of a control system;  
and if people are organized as control systems (and I think its fairly  
safe to say that they are, simply because they are locked into a  
negative feedback situation with respect to their own perception)  
then what I am saying is true; people compensate perfectly for  
disturbances to their own perceptual input, not because there  
is information or some usable representation about the disturbance  
in the input that allows people to compute, bleed off or whatever,  
the appropriate output but because their output is proportional  
to the difference between perception and a reference for that  
perception -- that's how it works. And the result is that the  
perecption is made to match the reference. Ahd since the reference  
is ultimately determine by the system (person) themselves, it  
means that people determine "what they do" meaning what they  
experimence so, in this sense, people are completely autonomous.

Ultimately, I don't think you can fully appreciate the significance  
and depth of PCT unless you can understand this apparently trivial  
little point:

In a control system, the perceptual signal contains no information  
about the environmental disturbances (or system outputs) that are  
acting to cause the variance in that perceptual signal. This means  
that the perecptual signal cannot be the cause, guide, source of  
information, or anything else regarding the appropriate outputs that  
should be made by the control system in order to produce the intended  
result (the reference value of the perecptual input).

Once you understand this, you can kiss all versions of the input-  
output approach to living systems goodby. It might be a painful  
divorce but, believe me, it opens the way to a MUCH better life  
of science.

Best

Richard S. Marken

"Religion is too important to be left to religions"