predictability, etc

CSGnet Archive CSG1995
1

[From Rick Marken (950502.1220)]

Bill Powers (950429.0915 MDT) to Martin Taylor:

If you could just accept that a control system needs NO information
about the world except about the state of its own controlled quantity,
you would see that control depends on properties of the closed loop and
on nothing else.

Martin Taylor (950502 11:30) --

And when have I said anything that would lead you to think I believe
otherwise?

Well, how about this, which follows shortly after your question:

Rick seemed to be making some kind of claim that the control system worked
by magic, whereas I tried to show that it worked by means of the perceptual
signal

But it DOESN'T work by means of the perceptual signal; that's the whole
point. A control system works because of the properties of the closed loop and
nothing else. The properties of the closed loop are the "magic" that makes
the control system work.

In a negative feedback control loop the perceptual signal is controlled; it
is made to be some particular value; it is forced (by the control loop) to
match the reference signal. The perceptual signal in a control loop is in no
position to make the loop work; in fact, the loop is working on it; the
control loop is controlling the perceptual siganl.

To an outside observer it LOOKS like perception (of stimuli, cues, affordance,
information, etc) guides behavior. This is the illusion under which the
behavioral sciences still labor; it is the basis of the lineal causal model
of behaivor: stimulus-->perception-->output--> behavior. I keep speaking to
this issue because I am trying to shout down the Sirens who try to seduce us
with their song "Perception: The control of behavior". Conventional
psychology has already crashed on the rocks; I don't want it to happen to you.

Best

Odysseus

2

[Martin Taylor 950503 11:00]

Rick Marken (950502.1220)

Bill Powers (950429.0915 MDT) to Martin Taylor:

If you could just accept that a control system needs NO information
about the world except about the state of its own controlled quantity,
you would see that control depends on properties of the closed loop and
on nothing else.

Martin Taylor (950502 11:30) --

And when have I said anything that would lead you to think I believe
otherwise?

Well, how about this, which follows shortly after your question:

Rick seemed to be making some kind of claim that the control system worked
by magic, whereas I tried to show that it worked by means of the perceptual
signal

But it DOESN'T work by means of the perceptual signal; that's the whole
point. A control system works because of the properties of the closed loop and
nothing else. The properties of the closed loop are the "magic" that makes
the control system work.

Partial list of the properties of the closed loop:

action output connections (many)
action output signals (many)
environmental feedback path
output function (many "properties" incorporated here)
error connection
error signal
reference inputs (many)
reference signal
reference input function (many "properties" possible here)
perceptual input function (many "properties" here)
sensory input connections
sensory input signals (many)
perceptual signal connection
perceptual signal.

I take it that your comment is intended to argue that such a breakout of
the "properties of the control loop" is not to be considered?

If you accept that the above list is a partial, though inexact, description
of some of the properties of the control loop, do you contend that one
should not enquire as to the role of any of these properties in the action
of the loop, or as to how the behaviour of the loop would change if the
value of one of these properties changes?

Note that "the perceptual signal" is included in the list.

In a negative feedback control loop the perceptual signal is controlled; it
is made to be some particular value; it is forced (by the control loop) to
match the reference signal. The perceptual signal in a control loop is in no
position to make the loop work; in fact, the loop is working on it; the
control loop is controlling the perceptual siganl.

Apart from the caveat that the word "approximately" should appear several
times, who could quarrel with this? But consider how well the control
loop would work in the absence of the perceptual signal!

Yes, you are right about the control loop.
No, you are wrong in saying that I said anything to the contrary.

What I did say, then and now, is that you are wrong to claim that the
perceptual signal is not the way that events in the outer world affect
the behaviour of the other signals in the loop.

Martin