Categories, Feedforward, Linear/Shminear

[From Rick Marken (931105.1500)]

Bill Powers (931105.1015) --

First, you're right in saying that at all levels, all perceptions
that are produced by a many-to-one transformation involve what we
call categories. Something remains the same while its components
can be in various states. But this specific relationship between
levels is not itself perceived. You have to have the concept of a
category with interchangeable members to PERCEIVE THAT a category
exists. When you apply this mode of perception to lower levels in
the diagram of the hierarchy, you can see this categoryness, even
though the lower levels themselves don't experience it.

By George, I think I'm getting it.

Somehow, category perception involves both the thing categorized
and the identity of the category. That is, you can look at one
specific screwdriver and see not only that it is what it is, but
that it is "a screwdriver," an example of a class of things.

Ok. So when I continue to see an "A" as it rotates in front of
me I am seeing the output of a configuration detector. But when
I see "A" at a particular angle as one instance of the many
possible rotations of "A" then I am seeing that instance from
the category level? Is that it?

What the category level does is reduce a world of continuous
variation and complete uniqueness to a far smaller number of
discrete symbols, which can then be used in place of a range of
lower-level perceptions.

I like that.

Perhaps in choosing the term "category" I have pulled a red
herring across the trail. A more explicit term might be "naming"
or "symbolizing."

I like that better. .

Our discussions of this level of perception may become clearer if
we think of the problem as that of creating and using labels to
stand for lower-level perceptions.

But we can label higher level perceptions too, no? Aren't there
categories of principles, for example: religious principles,
political principles, scientific principles, etc?

The harder this gets, the more I'm inclined to stop all this
guessing and get back to simple experiments.

What about my suggested category (now "name") experiment? It seems
like "vowel letters" is a nice example of the type of "name"
perception that you describe. It would be interesting to see if
it requires a slower presentation rate to allow a person to control
"vowel letter" (A,I,O,E,U) than it does to control a sequence (such
as ABCDABCD), as it should if the "name" level is above the sequence
level.

ยทยทยท

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Tom Bourbon (931105.1328) replying to Martin Taylor (931105 12:10) --

EXCELLENT post, Tom. I agree with eveything you said -- and more so.
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John Gardner (931104.1200) --

I simply couldn't let Hans 'twist in the wind' like this.

He raised himself up the ol' flagpole -- under feedforward
control, apparently, so don't worry; he can't possibly care
about the results of his posts.

I believe that the discussion
can take a much more fruitful turn if we examine the
hypothesis that most control systems contain elements of
both.

"Feedforward" (open loop) elements are already recognized
implicitly in PCT; they are just UNCONTROLLED variables.
Nothing in PCT rules out the existence of uncontrolled
variables as components of a feedback loop or as side effects
of control. Not every variable that is influenced by the actions
of an organism is under control -- that's one reason why we do
the test at all. Some variables that are part of feedback loops
are unquestionably NOT under closed loop control; for example,
when throwing a ball at a target, the movement of the ball after it
leaves the hand is obviously ballistic (open loop); disturbances
that influence the ball during this ballistic phase of it's
movement are NOT resisted. But this ballistic ball movement
is part of a control loop -- the loop that is controlling the
perception of final ball location; if the ball ends up in the
"wrong" place -- ie. if there is a discrepency between perceived
and reference ball destination then the thrower will adjust the
throwing effort (the feedforward "control") that produces the
ballistic phase of the next throw.

Anyway, I believe that the engineers would
argue that biological systems have a large element of
feedforward which specifies the 'neighborhood' of the
control actions. This effort is then aided with feedback
loops which 'fine tune' the behavior.

I would suspect that feedforward is a very SMALL element of
biological control systems; I can't imagine god would be
so negligent as to leave THAT much up to chance (though, after
the holocaust, Bosnia and poverty in America it's hard to over-
estimate god's negligence -- I'd rather blame it on evolution).
But this is an empirical question. A variable that is under
feedforward "control" is easily detected using "the test";
disturbances to such a variable will simply not be resisted.

The VAST majority of control theory is
based on the assumption that we are controlling a LINEAR
system.

Not true of PCT. But this reminds me. If it's not already in
there, I think the "control requires linearity" myth should
get a prominent place in the Devil's Bibliography -- along
with "feedback too slow" and all the other fun stuff.

Best

Rick