VI study, Psychophysics, Just say "no"

[From Rick Marken (980103.0930)]

Bruce Abbott --

I have been holding this rat's body weight constant by adjusting
supplemental feeding;


Why? I thought you were studying the rat's ability to control
its inputs, not your ability to control one of your inputs
(perception of the rat's weight). Why not cut these babies some

Bruce Abbott (971231.1430 EST) --

When you do a tracking study, you ask your participant to keep
the little cursor on the screen aligned with the target... I
don't have that advantage with my rat participants...By reducing
their weights I can be assured that...they a lever
if the food pellet... It's not really much
different than the social pressure you exert on your participants
to do as you ask, just more obvious.

It is quite different. My "social pressure" doesn't affect the
subject's ability to control the cursor _in the experimental
situation_; the subject has complete control over cursor
position so I can see the phenomenon of control very clearly and
I can model it precisely. Your "social pressure" (controlling the
rats access to food in order to control its weight) influences
the rats' ability to control food input _in (and out of) the
experimental situation_; the rat (unlike my subjects) cannot
have complete control over the hypothetical controlled variable
(food input) in the experimetal situation; it can't completely
control its food input at all since you (being stronger) are
producing insuperable disturbances to the rats' food input
when you control the rat's weight. Your VI experiment is just poor
experimental procedure from a control system point of view; but
it's a great conventional experiment. (By the way, your VI study
is the kind of garbage we hope you are _not_ going to pass
off in publications as PCT).

Bruce Abbott (980103.0805 EST)

As with any behavior, the participant's responses are actions
intended to control some variable or variables, but not the
perceptual variables being tested (e.g., a pure tone of a given

Since you don't test for controlled variables in these experiments,
you have no idea what perceptual variables the subject is
controlling. The subject may be controlling perceptions that
don't even involve the perceptual variable (like tone intensity)
under study. So you really learn very little (nothing?) about
perception from such experiments.

Psycholphysics was my field, Bruce. I did some great psychophysics
experiments and published a few. But once I learned PCT I realized
that the work I had done in psycholphysics was based on the wrong
model of behavior (input-output). So I stopped doing that kind
of research or relying on its results. It's really easy to give
this stuff up, Bruce. Just say "no" to conventional research. Once
you've done that, you can finally _start_ doing PCT.





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