[From Chris Cherpas (971010.1654 PT)]
Bill Powers (971008.0725 MDT)--
By all means play with the equations, and use actual numbers. I guarantee
that you's come out of it with a vastly increased understanding.
Thanks for the exercises concerning amplification and slowing.
They helped, especially in seeing monotonic vs oscillating patterns.
Of course, a vast increase in understanding does not necessarily mean
the absolute level of understand is that great!
I got another perspective, indirectly, after just reading Powers (1979)
"A Cybernetic Model for Research in Human Development," also in
_Living Control Systems_.
Bill Powers (1979, pp183-184)--
"There are many ad hoc solutions to this problem, involving variable
control of speed and nonlinearities with just the right properties,
but they are all complex in comparison to the one I propose. I assume
that in most human control behaviors, error sensitivity is very high,
so high that under normal conditions there is essentially 0 error
at all times. To take care of the deleterious effects of too much
error, I simply assume that reference signals normally vary
continuously, not in an on-off manner."
This article, especially at the end, when a particular order is
considered for developing a new control system, is really getting
me thinking about a PCT approach to structure certain computer-based
tutorial sequences...
Bill Powers (1979, pp183-184)--
(1) perception: the variable to be controlled must exist as a neural
analogue;
(2) recording: the possible states of that variable must be experienced
and remembered;
(3) selection: one previous state of the variable must be selected as
a reference signal;
(4) comparison: the error between the actual and intended states of the
variable must be judged;
(5) action: the error must be converted into those changes of existing
lower-level reference signals that will correct the error;
(6) practice: this entire series must be iterated over and over to
refine each element of the control system so that it functions
under all conditions without instability.
We currently do a lot of (6), without being all that specific about
what goes into (1)-(5). Sometimes a developmental sequence builds
up to the point where you pretty much have to face a kind of crisis
that only acquiring a higher order control system can resolve (something
Hugh Petrie wrote about), but that isn't the "normal" mode of
education, pretty much by definition. Also, to modularize the
material, it's handy to have different "modes" (testing, tutorial,
practice, review, etc.). Obviously, the test for a controlled variable
is a useful procedure for thinking about the way a "testing mode" works.
Bill Powers (971008.0725 MDT)--
A reference signal can skip levels only if there is no control system
active at an intermediate level. The reason is obvious: if the reference
signal results in a perceptual signal changing at a lower level, the
intermediate level system will see an unwanted change in its own
perception, and will change its output to the lower level to correct the
change. In doing so it will cancel or partly cancel the effect of the
higher level's output, leading to conflict.
Nice. You sure talk good for an engineer. Regarding the
educational enterprise again, there's been a lot of work specifying
standards ("educational objectives") for grades K-12 by
state/fed governments over the last decade and it seems to keep
increasing. A big problem is that it's really hard to see how
these statements are supposed to be translated into curricula.
The connections are loose, or exemplar-based at best. By analyzing
a pretty big sample of these, I've found some of the "best" exhibit a
kind of how/why structure, even if the specification of the "target"
controlled quantity is vague. Specifying something about adjacent
levels helps. Your resolving my confusion about reference signals
skipping levels adds another constraint to this jello-like world.
Meanwhile, another problem has reared its ugly head as I study the ways
of the PCT: Powers (1979) had only 10 levels which reminded me that I
have trouble seeing the sequence level as it is in the 11-level structure.
Mostly, sequences seem really specific to me. "What are they doing way up
there above categories?" When a sequence is under good control,
it seems unitary _like_ an event that has events in it.
If I do recognize a general series ("ah, it's one of _those_ kinds of
sequences"), then I think this could be a variant of categories.
If I lose control of a specific sequence ("now what comes after abcdefg...?"),
I seem to "start" down at the relation level (nextness, the precedence
relation) to fix it. As that fails, I might start reasoning at the program
level, maybe "using" categories such as beginning, middle, end, etc.,
but trying running starts and testing specific possibilities which seem to be
perceived at the same "kind of level" (whatever that could mean)
as events. I can reconstruct a lost sequence, so to speak, but it doesn't sound
right until it has a wonderful lower-than-relation feel to it. So,
even after locating the missing part, I run through faster and faster
until it's all down there where it belongs.
Maybe the words "event" and "sequence" need to be combined to name that
level better -- sevent? evquence? While at the category level, there
are those more general series -- Cateries? Sategories?
Maybe there's an analogy to configurations here. A configuration has
a certain unity to it, like an event, but it can sub-configurations, and
same so for sub-events. Finally, a configuration is not just the
right _collection_ of edges/etc. (e.g., it's not OK to have the mouth
on the forehead to be your friend's face); and a sequency event, isn't
just the right collection of transitions/etc. -- order matters. And
when order matters, don't you perceive sequence?
Best regards,
cc