Anastasio to Bourbon


I'd like to thank Tom B for his reply, and to add a few short comments.

Tom A

It would be really nice to see someone who is equipped to do
neurophysiology who caved in and did direct physiological tests of the PCT
model -- tests of the idea that nervous systems control the magnitudes of
their own sensory signals. Think you can keep working on him, Gary?

I may try this someday, if I move from lower to higher brain levels in by
research. May I also suggest that HPCT researchers consider developing their
own skills in neurophysiology?

>No one will argue against the idea that a driver uses negative feedback to
>steer a car down the road.

It is pretty clear that Tom A. never encountered reviewers like ours! Some
of them would even argue that cars and roads are trappings of Western
colonialism and that anyone who attaches importance to data about how people
control cars must be a degenerate capitalistic logical positivist from before
the post-scientific era. And everyone knows positive feedback is more
aesthetically pleasing than the negative kind. (I'm not kidding, there are
such reviewers out there, and they have had their say about PCT.)

These comments are truely unbelievable! They indicate that the area you
work in is still far from being a "science" in the sense of Kuhn. It is an
area in dire need of structure. Were it to be accepted, HPCT could fill
that void. I wish you the best of luck.

But the biggest potential problem in that sentence has to do with a person
steering a car down the road. Yes, perhaps, but not as that process looks
to an observer -- PCT is about the view from the inside, from the driver's
perspective. This sentence might be a casual shorthand version of, "but we
all really know that ...", or it might be an indicator that the writer is
thinking of PCT as a "commands-followed-by-a-servo" model, like those
popular right now in parts of cognitive science.

The example of control in the oculomotor system that I give Gary is the
optokinetic system, with which you are probably familiar. Its function can
be stated in two ways: 1) to match eye velocity with that of the visual
world (motor), 2) to minimize visual image slip (perceptual). Both
descriptions are used and both say the same thing given the obvious
structure of the optokinetic system as a control system. But I can see how
one would want to emphasize the perceptual aspects when trying to explain
phenomena on the behavioral level. I believe it is on this level that
HPCT makes its most important contributions.

>What will really convince scientists is hard
>data, the more neurophysiological the better, that begins to flesh out HPCT.

Sigh. Agreements between a model's predictions and a person's results that
rival the level of precision in parts of physical science, but they do not
count (more logical positivism?), but something really *hard* *would* count.

I'm just getting to chapter 16 in Powers '73 on experimental results.
Verification at the precision you describe would be hard enough for me.

Let me close by reiterating my suggestion that Powers' manuscript (the one
circulating) include the data you describe. I assure you that if you hit
neurophysiologists over the head with hard data, some are bound to feel it!

Tom Anastasio.

From Tom Bourbon (930511.1107)

Gary, would you please pass this note along to Tom A.? Thanks, in advance.


I'd like to thank Tom B for his reply, and to add a few short comments.


Tom Anastasio.

There is no need to go into a detailed reply to Tom A., just a genuine,
"thank you," for reading our posts and for some (in our experience)
remarkably positive and encouraging replies to each of us -- Bill Powers,
Greg Willliams, and me.

In reply to my wish that a trained neurophysiologist might some day take up
the challenge of testing for control by physiological systems, you urged
PCTers to do the reverse, acquire some physiological skills. At the level of
gross physiology -- nearer psychophysiology than anything else, that is what
I am trying to do, in what Bill Powers referred to the other day as my "new
career." But this dog is not getting any younger. My real hope is to
entice someone into the game, and a medical school seems to be a more
likely place than my former obscure state university. Wherever I conduct my
hunt, I doubt that I will be lucky enough to find a candidate whose initial
interaction with PCT and PCTers is as cordial and supportive as yours.

Good journey to you.
Until later,
  Tom Bourbon