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Date:         Fri, 20 Nov 1992 14:45:58 -0700
From:         "William T. Powers" <POWERS_W%FLC@VAXF.COLORADO.EDU>
Subject:      Complex perceptions

[From Bill Powers (921120.1300)]

Martin Taylor (921120.1340)]

You replying to Rick:

>The question in my mind is: why should it be true that
>>at some point, some resource (a cell or cell assembly) is going
>>to have to represent the state of the distributed representation
>>to someone other than the person watching the model -- ie. there
>>will have to be a perceptual signal that represents the state
>>of the distributed representation...

The "someone else" is a higher level system. This discussion is
making me go back through some old musty trains of thought that
eventually led to HPCT.

When you have a set of ECSs at a given level, each one provides a
controllable perceptual signal (there are also uncontrolled ones, in
general, at the same level). A copy of the controlled signal is
available to higher-level systems. The question before us is whether
these independent control systems can produce a "complex" of
perceptual signals that has some specific pattern in it, so the
whole ensemble of perceptual signals has some significance other
than that of each individual signal.

The basic answer of HPCT is no, that isn't how hierarchical
perception is supposed to work in this theory. To see why not,
consider controlling for some linear combination of the perceptual
signals by setting each signal to conform to one element of a
pattern. To do this it would be necessary for a higher system to set
the reference signals for each of the lower ECSs to satisfy the same
linear combination. In the event that the linear combination (or
nonlinear for that matter) were made up partly of the uncontrolled
perceptions, there would be no way to specify reference signals that
would satisfy the specification.

In the hierarchical model, a linear combination of the lower level
signals would first have to be sensed and converted to a single
signal by the higher system's perceptual function. That function
would contain exactly the linear combination to be controlled --
that is, the weightings would represent the coefficients and the
computing operations like adding, subtracting, multiplying, etc.,
would do the combining. This single signal would be compared against
a single reference signal, and the single error signal would fan out
to the lower reference inputs with appropriate positive and negative
weightings. But these output weightings now do not represent the
linear combination itself, but only signs of effects. As long as the
sign is correct in each output path for making the higher-level
error smaller, no output weighting is strictly necessary (although
it can help).

The important thing to see here is that there is no one distribution
of the lower-level perceptual signals -- no one "pattern" --  that
is necessary for achieving a particular value of the higher-levelscalar
 perceptual signal. What the higher system is controlling is
not a particular set of values of the lower-level perceptions, but a
particular multidimensional relationship among them, or more
precisely a function of them. There are many ways in which those
lower-level signals can vary without altering the value of the
function and hence the higher-level perceptual signal. Changes in
the pattern of lower-level signals that do not alter the higher-
level perceptual signal are simply not controlled (except by
individual systems at the lower level). It is not necessary for all
the perceptual signals at the lower level to be under control, nor
is it necessary to protect them against variation. If uncontrolled
perceptions vary, the controllable perceptions can generally be
altered to restore the value of the function to its specified level.

In connecting this picture to conscious experience, confusion arises
because we can be aware of more than one level of perceptual signals
at once. When I look in the basket hanging at the top of the stairs,
I see a letter in it. Ah. A letter in the mail basket. Then some
higher-level perceptual functions kick in, and now I see, oh crap,
an UNMAILED letter that was supposed to go out today, and Mary has
already left for town (don't worry, Mary, I'm making this up).

Now where was that "unmailed-ness" when I first looked at the
letter? Objectively, I was looking at an unmailed letter from the
very start. But I didn't _perceive_ its unmailedness. The mere
existence of the configuration and relationship perceptions was not
enough. Some higher-level system had to perceive these elements, put
them together into a perception of the state of mailed-ness, compare
that with the desired state, and come up with an error big enough to
attract my attention. THEN I experienced the significance of the
pattern of lower-level perceptions. I still perceived the
configurations and relationships. But now I also perceived a new
signal. If I had intended to delay mailing it, I might then say
good, she remembered not to take it.

This is why I say that it's not enough for a pattern to be implicit
in a set of variables. An implicit pattern can have no meaning to a
higher system. In fact, thinking of patterns in collections of
perceptual signals is backward to the HPCT way of modeling
perception. I know it's customary in conventional approaches to
think of the pattern than is present and try to design a recognizer
for it. But in HPCT there is no "inherent" pattern.

The HPCT view is that the pattern is imposed from above. When a
higher perceptual function becomes organized, it receives signals
that are lower-level perceptions, puts them through some sort of
computing function, and delivers a perceptual signal carrying the
scalar value of that function. The form of the computing function
determines completely how the perceptual signal will vary as the
lower-level perceptions individually vary. EVERY function will
produce a perceptual signal of some magnitude. EVERY function with
multiple arguments defines some sort of invariant. ANY ARBITRARY
function of the lower-level signals can be brought under control,
provided only that the value of the function can be systematically
affected by altering reference signals going to lower-level systems.

No matter what the form of the function, it defines a pattern in the
lower-level signals, an invariant. Other higher-level systems can
employ different forms of perceptual functions using the same lower
signals as inputs or arguments; they will perceive and control a
different pattern in those same lower-level signals, at the same
time (if there is sufficient orthogonality).

We do not learn to perceive patterns that are "really there." We
learn to perceive patterns that are useful to control. Somewhere,
way off in the philosophical distance, there may be a deep principle
involved, to the effect that the patterns that prove to be the most
useful to control, in terms of the effect of doing so on critical
variables, happen to relate in some way to something that is in some
sense "really there." But organisms do not know what is really
there. They know, or learn, only that seeing the world in particular
ways, and controlling what is seen relative to particular reference
levels, feels better than not doing so. No philosophy, except in
some human beings who have taken up the habit.

I think that the idea of complex perceptions, vectors that have
meaning in themselves, is a vestige of an older way of modeling
behavior based on a realist epistemology. We certainly experience
multiplicity of perceptions. But until we form the right perceptual
functions at a higher level, we do not perceive pattern in them, and
none of the implicit patterns, infinite in number, has any effect.

An exercise that I went through frequently in developing definitions
of levels of perception was to try to imagine what the world would
be like if a given level were the top one. Suppose, for example that
the top level was configuration (as it must be in some sufficiently
simple organisms). Watching someone blow up a balloon, one would see
"Limp rag, limp rag, balloon, balloon, balloon, (POW!), no balloon."
There would be no perception of transition, no sense of the balloon
getting larger and larger. There would be no relationship between
one size of the balloon and another size of it. One state of the
balloon would have no causal relationship to any other state. There
would be no logical relationship between the size of the balloon and
its bursting; in fact its bursting would not constitute an event.
There would be only shapes.

By using this ploy with various levels of perception, you can begin
to see what a higher-level perception is. It's a new signal,
appearing in experience along with all the other lower-level signals
that are already present. When you see the balloon increasing in
size, you still see the shape at every moment and the color and the
edges and curvatures. But a new signal appears that is not present
when the balloon remains at constant size. This new signal is the
sense of transition, of growing. It has no other character. It is
simply a signal that occurs when someone blows more air into the
balloon. You can't take this signal apart into elements; it is
unitary. This signal IS what we mean by the term "expanding." It
does not refer to anything else; it is that to which we refer with
words denoting a change in size. We refer to a small magnitude of
this signal by using words like "slowly" or "gradually." A largemagnitude is
 what we mean by "rapidly." Zero magnitude is what we
mean by "constant" -- a word that has no meaning unless you're
capable of perceiving transitions.

What you end up with is a picture of your own world as a collection
of attributes or aspects each of which is just a single variable
amount of something. This is true even for such an abstract
perception as honesty. You can enumerate lower-level perceptions
from which this sense of honesty is derived, but the honesty-signal
itself is just a signal, with no fine structure.

One perception, one signal.
-------------------------------------------------------------------
Best,

Bill P.
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