[From Rick Marken (980223.1000)]
Bruce Abbott (980223.0955 EST)--
It would appear that Rick's disagreement with Fred comes down to
whether the disturbance should be defined as d or as g(d).
No. It's whether the disturbance should be defined as d (variations
in environmental variables) or c (variations in controlled variables).
I think you would do well to carefully re-read this thread
(particularly Rick Marken (980222.1710),Bruce Gregory(980222.2114 EST)
and Bill Powers (980222.0447 MST)) because (as Bill noted) this is
a _very_ important topic. The most important thing to understand
is that, in a well-functioning ("tight") control system, disturbance
variations (variations in d or g(d)) hardly show up _at all_ as
variations in the controlled variable. This is what the first
two demos at http://home.earthlink.net/~rmarken/demos.html show.
This is what destroys the foundations of conventional psychology.
It does it by rejecting the causal model of behavior (the model
on which all behavioral research to date has been based). I think
that once you are able to understand and/or accept this point
[that variations in disturbance variables are _not_ reflected
in variations of the controlled variable] you will be able to
stop fighting so hard against PCT and start acting as its true