[From Rick Marken (960622.1215)]
Regarding my earlier post [Rick Marken (960622.1040)] I forgot
to mention the point of the whole thing.
The point is that, even though a higher oder system can perceive
and control the "informativeness" of the relationship between
a perceptual signal and other variables in a control loop such
as the control systems own outputs and possible disturbance
variables, this has nothing to do with how the control system
itself controls. "Informativeness" is something that can be perceived
_about_ the behavior of a control system (when the system is looked
at from a higher level); but it is of interest only to the system
doing the observing; it has nothing to to with how the way the observed
control system actually operates. For example, when we observe a
control system in a tracking task, we can see that its outputs mirror
variations in the disturbance to to the cursor. We can see this mirror
relationship but the system doing the tracking cannot. The mirror
relatinship that we see is an _irrelevant side effect_ of controlling.
Saying that the information in perception is essential for control is
like saying a mirror image relationship between disturbance and output
is essential for control. It's just a mistake -- but one that can be
costly because it can (as it has for the last 100 years) point research
on living systems in exactly the wrong direction.
That's why it matters.
Best
Rick