Functional mapping; basics of PCT

[From Bill Powers (940226.0800 MST)]

Bill Leach (940225.2112) --

I am quite happy to say that I believe that I fully understood
Bill's posting. The functional mapping is no problem to me
BECAUSE PCT really does map the functions and not just play
games with the terms!

Why haven't I ever thought of putting it that way? That's exactly
what we try to do! We try to map the functions (and signals and
physical variables) in a simple control system model to
functions, signals, and physical variables in real behavior.
Naturally, this requires some guessing about the functions and
signals inside the real person, but that's the modeling game.

From various indirect evidence, including personal and behavioral

evidence but also taking into account what physiological and
neurological information is available (that we can make any sense
of), we try to deduce functions and signals that actually exist
in the central nervous system. Of course we can directly observe
and measure the physical variables and functions outside the
system in an experiment, so we don't have to guess about that
part of the model.

What we're always after is the _minimum_ model of a person's
insides that would account for what we observe. Our models have
to be taken as representative or equivalent models, not as
literal maps: they accomplish the same overall result, but not
necessarily in the same detailed way that the nervous system does
it. However, if we propose an input function (for example) that
receives position information and generates a neural signal
indicating rotation rate, as in controlling the angular velocity
of a rotating line on a screen, we are saying that there IS some
input function in the real nervous system capable of computing
rotation rate given a series of position signals, even if we
don't know how it works. The model contains a number of black
boxes labeled according to the input-output relationship they
have to establish, but we don't try to guess at the inner
structure of the black boxes. As you know there is an infinite
number of ways to construct a computing network that will create
a given input-output function. The only way to find out what the
actual wiring is is to open the black box and look. So far, none
of us is licensed to do that.

As a linguist on the net in Australia, Avery Andrews, said, what
we're doing is reverse-engineering behavior.

One of the most useful pieces of evidence is perception. A major
postulate is that when we consciously experience the world or our
bodies, we are being aware of the content of the perceptual
signals emitted by input functions at various levels in a
hierarchy of perceptions in our brains. In other words, if I see
a cubical paperweight on the table in front of me, I am being
directly aware of perceptual signals representing all the
attributes of what I see: the cube-ness, the table, the "on-
ness", the "in-front-ness", the "paperweight-ness", and so on --
a large number of perceptual signals each standing for some
function of the basic inputs to my visual receptors. Most of
these perceptual signals can be controlled by acting on the

If this is really what these experiences signify, then it should
be possible to deduce some relationships in the hierarchy of
perceptions by examining all these perceptual signals to see how
they depend on each other. Some perceptions should be functions
of others: the dependent perceptions should change when the ones
they depend on change, and the dependent perceptions should be
nonexistent when the ones they depend on don't exist. Controlling
a dependent perception should require, absolutely, varying the
perceptions on which it depends. If a perception is under
control, disturbing one of the perceptions on which it depends
should result in behavior that either opposes that change
directly, or results in changing one of the other perceptions so
that the dependent perception remains (nearly) the same.

It is possible to find classes of perception that show these
relationships -- that's what my proposed 11 levels of perception
and control are about. For example, if you examine
"configurations" (level 3, roughly objects), and try to find
perceptions on which they depend but which are not just smaller
configurations, you come up with shading, color, edge, curvature,
and so on -- the class of perceptions I call "sensations." And if
you look at any one sensation, you find that it depends only on
the amounts, magnitudes, of stimulation of given kinds -- the
level I call "intensities," the bottom level. Only the bottom
level is directly affected by stimulation from the environment.
And going upward, you can ask what kind of perception depends on
the existence of configurations (looking for the least possible
step), and you come up with, I think, "transitions," which
includes motion. Then, seemingly, continuing upward, you get
events, relationships, categories, sequence or ordering, programs
(rule-following), principles, and system concepts. Each level
depends on the levels below. Similar levels can be found in all
sensory modalities.

All this is very much subject to revisions, deletions, and
additions, and of course the whole thing needs experimental
testing. The nice thing about PCT is that you can actually test
for control of perceptions, and thus find out if the perception
really exists (from the experimenter's point of view). If you
want to know whether a person can control the state of a logical
proposition, for example, (the 9th level as currently numbered)
you make the truth-value of the proposition depend on some lower-
level perceptions, ask the subject to keep the proposition true
(or false), and disturb the lower-level perceptions to see if the
person's action opposes the effect of the disturbance either
directly or through altering other perceptions (other variables
in the proposition). If the person can control the state of the
logical proposition, then obviously the person must be perceiving
it. Ultimately, this sort of testing, done for perceptions at all
levels, should enable us to sort out what the levels really are
and how they are really related, if in fact they exist at all.
The hierarchical control model is set up so that all loops, at
every level, are closed through the environment. So you can
always test for control at any level through a behavioral

Before that sort of major project can be undertaken, PCT has to
become airborne enough so that we don't have to spend all our
time just defending our existence and overcoming the massive
opposition to expending funds on this silly, narrow, old-
fashioned, elementary, simple-minded, unscholarly,
unintellectual, naive engineering approach to understanding
behavior. This is not a small project and it can't be done by
four or five people scattered around the country doing
experiments in their spare time on themselves and their families
with home computers and no money, while making a living doing
something else. As the nucleus of a scientific revolution, PCT
has developed far enough to suggest numerous lines of research.
The main problem now is for competent understanding of it to
spread far enough that this sort of research becomes respectable
and fundable.

As funding is a zero-sum game, the implication is that other
lines of research will have to be perceived as less promising, so
funding can be shifted appropriately. That, of course, is the BIG
POLITICAL PROBLEM. Nobody following another line of investigation
wants to be the one whose pet theory is deemed less promising
than PCT. For the threatened, there are two solutions to that
problem: (1) fight like hell to show that PCT is (a) wrong, (b)
trivial, or (c) just a subset of what you are already doing, or
(2) adopt PCT and join the revolution. So far even on this net
and more so elsewhere there is a lot more of (1) than (2). One
way to judge the power of PCT is to look at the energy expended
in defending against it (that's just good control theory).

I think that any distinterested party who has been following csg-
l for two or three years must have noticed how many _different_
ideas are ranged against PCT. Practically every approach to human
behavior, it seems, is disturbed by the statements that PCT
generates. Objections to PCT arise from every quarter, even
quarters that staunchly disgree with each other. Practically
every objector also claims that the basic concepts of PCT were
anticipated in his field or are contained in it. This is a very
interesting circumstance, because it says that PCT is relevant
enough to many different fields to have some of its conclusions
accepted by them, and also that it differs from them enough to
cause considerable pain. One might conclude that PCT agrees with
what is right in these fields, and disagrees with what is wrong
in them. But of course a single proponent of a single field of
investigation sees the situation only from one point of view,
claiming the agreeable parts of PCT and rejecting the parts that
seem flawed. The fact that a person in a different field might
accept and reject different parts of it isn't evident unless
you're paying attention to ALL the objections, as we who sit here
in the middle necessarily do.

Well, Bill L., you got back more than you asked for, but I have a
hunch that you're about to join us, so maybe all this is



Bill P.

<[Bill Leach 940228.19:14 EST(EDT)]

[Bill Powers (940226.0800 MST)]


I have been "getting more than I bargined for" since I first arrived
here. :slight_smile: And I don't mind it a bit.

As is usual for about anything that I have seen you post, there is plenty
there and a great deal to think about. Thank you again.