[From Rick Marken (931218.1500)]
Bill Powers (931217.1940 MST) --
Wow! Great post.
What we have now, apparently, is a behavioral science community
that is far more interested in controlling it's wonderfully complex
imaginations than in starting all over again, from scratch. All PCT
offers is the opportunity to do the latter. What a choice! And we
wonder, sometimes, why people aren't flocking to PCT.
Martin Taylor (931218 1230)--
But I suppose I could try a one-ball-at-a-time description of a vortex.
I am interested in the vortex because I want to see in what way it
involves negative feedback. I am really only curious because I
think it might help us clarify the difference between purposeful and
non-purposeful systems. Here is the kind of diagram I had in mind:
d-->i-->|system|-->o
^ |
>---------------
This is a VERY simple closed loop system. The variables are the
usual suspects -- disturbance (d) and output (o) variables contribute
to the value of an input variable (i) that leads, via the system,
to the output. The sense of the feedback is negative if i = g(o)
and o = -f(i). Each of these variables can be identified with
aspects of a real control system: for example, d could be the height
of an object in the environment, i is it's retinal height, and o is the
distance from retina to object. If the system has sufficient gain
then retinal height will be stabilized despite variations in the height
of the object.
I don't know how to do this for a vortex. What corresponds to d, i and
o in a vortex? What is the system in a vortex? Does the above diagram
not work for a vortex? What diagram does work for a vortex?
These are the kinds of things I'd like to know.
Thanks
Rick