[From Rick Marken (951215.0840)]
Bruce Abbott (951214.1635 EST) to Bill Powers (951213.0805 MST) --
Apparently I should not have telegraphed my intentions; you have used the
advance notice to launch a pre-emptive strike designed to nullify virtually
_any_ suggestion I might offer even before I have made it.
Pre-emptive strike? There was no strike at you, Bruce. Bill's on your side.
He, like you and me and the rest of us who understand PCT, is trying to show
that reinforcement theory is the "Ptolomaic" explanation of the phenomenon
called "reinforcement" (behavior and contingent reinforcement rate rise
to an asymptotic value over time); PCT is the far more elegant "Copernican"
explanation of that behavioral phenomenon.
Bill derived the simplest mathematical versions of the two models of the
reinforcemnt phenomenon:
Reinforcement: dB/dt = k1*C - k2*B
PCT: dB/dt = k1*(Co - C)
and pointed out that the solution of the differential equation for the
reinforcement model is an exponential runaway or no behavior at all, neither
of which is actually observed. Bill pointed out that the reinforcement model
could probably be salvaged by making some ad hoc assumptions about rate
limiting processes. Then Bill made a statement to which you seemed to take
considerable offense:
But to look for a "rate-limiting" process is simply to say "Even if the
basic model predicts incorrectly, I choose to defend it."
Perhaps you would find this statement less offensive if you could see that
the addition of "rate-limiting" processes to the reinforcement model is
perfectly comparable to adding epicycles to the Ptolomaic model; it can be
done -- and it might even get the model to work -- but it suggests that
something is fundamentally wrong with the model since there is no independent
basis for making these ad hoc assumptions.
The PCT model, in it's simplest form, explains the basic reinforcement
phenomenon accurately. The PCT model is not perfect yet (just as Copernicus
needed the orbits to be elliptical rather than circular); but continued
experiment comparing both models will (hopefully) show that the PCT model
requires the addition of fewer ad hoc assumptions to keep up with the data
than does the reinforcement model.
This is why we need to do the human operant conditioning experiments. We need
to design experiments that will clearly discriminate the predictions of these
two fundamentally different conceptions of the nature of living systems.
Hopefully, we will be able to do a sequence of experiments that will show
how difficult it is to maintain (via the continual addition of new ad hoc
assumptions) the concept of behavior as controlled or selected by its
consequences (the reinforcement model) and how easy it is to maintain the
concept of behavior as the control of perception (the PCT model).
This is what you want to show, too, isn't it Bruce?
Best
Rick