Control of perception, output, or action

[From Rick Marken (981001.1305)]

Bruce Abbott (980930.1715 EST) --


                    feedback v error
             ^ |
             > >
                    output ^ action

I think what is most depressing about this diagram, aside from
the fact that it shows that you are really never going to stop
trying to see PCT as "nothing but" conventional psychology, is
that it seems like an attempt to represent the insights of PCT
as nothing more than re-labelings of a diagram.

The central insight of PCT is the organisms control perceptual
representations of environmental variables. One of the most
important implications of this insight is that you can't tell
what an organism is doing (what representation of the environment
it is controlling) by simply looking at the behavior of variables
in the the organism's environment [see "The Test for the Controlled
Variable" demo at]. You
have to test to determine which of your _own_ perceptions corresponds
to the representation of the environment controlled by the organism;
this perception is called the _controlled variable_. PCT describes
several formal methods -- collectively referred to as "The Test" --
that can be used to identify controlled variables.

In the diagram above, the controlled variable is called "output".
The diagram purports to show that what psychologists like
Ramachandran and Blakeslee call "output" is the same as what PCT
calls the "controlled variable". If this is true, however, there
should be some evidence that psychologists have done some version
of The Test to determine which of their own perceptions corresponds
to the "output" they say is controlled. I am aware of no evidence
that psychologists do this kind of Test; "outputs" are simply what
psychologists say they are: arm movements, bar presses, rating
responses. etc. In fact, the actual "output" that is controlled by
an organism may be something other than what the psychologist says
it is. As far as I know, this possibility -- the possibility that the
organism is controlling something other than what the psychologist
dubs its "output" -- is never seriously considered.

I think it's _highly_ unlikely that Ramachandran and Blakeslee
used the word "output" to refer to a controlled perceptual
representation of the environment. But, if they did, they were
talking to an unusual audience of behavioral scientists -- the
ones who think "outputs", the perceptual consequence of action,
are controlled. Apparently most behavioral scientists -- at least
those in the audience of the premier journal of scientific
psychology; Journal of Experimental Psychology: Human Perception
and Performance ( JEP:HPP) -- seem to think that is _actions_ that
are controlled, not "outputs". I infer this from the description
of JEP:HPP found at

"The Journal of Experimental Psychology: Human Perception and
Performance publishes studies on perception, formulation and
control of action...".




Richard S. Marken Phone or Fax: 310 474-0313
Life Learning Associates e-mail: