[From Bill Powers (960709.1030 MDT)]
Dag Forssell (960706 23:55) --
Dag, thank you effusively for the time and labor you put into showing us
Bruce Gregory's book, _Inventing Reality_. It is a beautiful work, and
explains entirely why Bruce finds PCT so compatible. Both you and Bruce
have done us all a great favor. Mary has already launched her project
for finding a copy.
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To Bruce:
I think you have taken the first step toward another level of
unification of science. PCT, or something that will grow out of PCT, is
the second step. Your book shows that physics is modeling; it is making
up plausible and testable stories to explain what we observe. The step
that follows this realization is to see that what we observe is what we
perceive, and that what we perceive is what _human beings_ perceive.
Physics is evidence about how the human brain works, to at least the
same extent that it is about an objective universe.
Several times in the past I have said that whatever our model of
perception may be, it has to explain how the world appears to us. This
claim has been more or less dismissed by some of our participants; the
comment is something like, "Oh, that's just subjective perception, and
you can't tell what's really going on in the brain from that."
This has come up in the context of stochastic models. One of my main
reservations concerning all the talk about uncertainty and noise in
perception is simply that when I look around, I don't see a noisy world.
The world I experience is essentially noise-free, although of course it
contains more detail than I can comprehend. What all my senses seem to
present to me is a smoothly-changing continuous and grainless world. It
may be unpredictable on a slow time-scale, but on a fast time-scale it
does not look the way I would imagine a stochastic world to look. Under
normal circumstances, the signal-to-noise ratio seems to be very high.
The question here is what we are going to treat as primary observation
when it comes to explaining brain function. Are we to treat records of
neural impulses or subjective perception as primary? If we decide to
treat measurements of neural impulses (and other physical measures) as
primary, then we are saying that reality is what our theories and models
tell us, and not what direct experience tells us. I believe this is
seriously wrong.
How do we test any theory or model? We imagine or calculate how the
model would respond to some simulated event, and then we observe how the
real world responds to the actual event. And how do we observe this?
With our subjective perceptions. It has been said that physical
measurement, ideally, reduces to the judgement of the position of a
pointer relative to a mark on a scale. The hope is that by making
observations this simple, we can avoid personal biases that might alter
the data. But there is a great deal more to observation than this.
Not only do we observe a pointer and a mark as separate objects, and a
spatial relationship between them, but we also observe changes in the
readings, and momentary patterns of fluctuation that we treat as events,
and categories of measurements, and sequential ordering of measurements,
and logical functions of multiple measurements, and principles that are
generalizations from the logical functions, and system concepts that we
experience as organized bodies of principles; physics and mathematics.
Observation involves all levels of human perception.
Normally we project some of these different levels of perception into an
independent objective world, so that for example events, rather than
being apprehended as arbitrary chunkings of a continuous world of
experience, are seen as "happening" in the objective reality. The events
happen out there, and then we think about them in here. We divide the
world of experience into "inside" and "outside," acknowledging our part
in creating the "inside" processes, but treating the "outside" as being
independent of us.
The PCT model has it otherwise. It is built on the basic principle that
observation is simply perception, and that perception is a process of
representing functions of input variables as scalar output variables. In
short, observation is always subjective perception, at whatever level it
occurs.
When we test a theory or model against reality, we always test it
against subjective perceptions. We may use artificial aids to provide us
with indications of what is going on, but it is still up to us to
recognize that measurement A is greater than measurement B, or that
measurement A occurred before measurement B, or that a relationship
among measurements belongs to a certain category such as similarity or
symmetry. We have no choice but to trust these impressions of relative
size or time of occurrance or classification. The world we experience is
the result of some kind of reality as it intersects with the properties
of human perception. It is only the perception of which we can know
directly.
So the ultimate test of any theory or model is whether it predicts what
we actually experience at all levels from intensities to system
concepts. If the theory predicts that A will occur before B, and we
experience B before A, then the theory is wrong. The internal
consistency of a theory is quite irrelevant if it predicts contrary to
direct subjective experience.
There have been many arguments against this point of view. Bruce Gregory
mentioned one of them: the Ames Room. Here we have a viewer seeing a
person apparently -- perceptually -- growing and shrinking simply by
moving laterally across the room. This would see to argue that
perception is unreliable, that reality can be different from perception,
and that we ought to trust physical knowledge before we trust subjective
impressions. What the viewer perceives is obviously different from what
is really going on.
But how do we know what is "really going on?" Even the viewer of the
Ames Room can quickly see that there has been an illusion, simply by
moving to one side and viewing the room from a different perspective.
Physical measurement will show that the person in the room has not
changed size; all we have to do is hold a tape measure up against the
person and perceive that the reading doesn't change. We can measure the
room and perceive that the dimensions of the room are not rectangular as
they seem from the viewer's special vantage point. By changing our
perceived relationship to the room, we can quickly discover that there
is an inconsistency between one set of perceptions and another set, the
viewer's original set.
But where does "what is really going on" enter into this? All we have
done is compare one set of perceptions with another set obtained under
changed circumstances. We are still judging in terms of our own
perceptions. There's no way around it. We distrust one perception, the
perception of the person who shrinks and expands, but only because we
trust other perceptions more. Nowhere in this process does the true
nature of reality come into the picture. We are working entirely within
a subjective world of direct experience.
In fact, what the viewer of the Ames Room sees is perfectly correct,
given the available knowledge. Because binocular vision is prevented,
and because only a single carefully-placed viewpoint is available, what
the viewer sees is what the viewer sees. It is only theory that tells
the viewer that the person moving around in the room isn't actually
changing size. The changing size is one valid intepretation of the
scene; there is no direct evidence to the contrary. Only past experience
contradicts what seems to be happening. And a very simple change of
viewpoint will quickly reveal alternative explanations.
Now apply this to the phenomenon of noiseless perception. When you or
any person looks around the room, you see walls, floor, ceiling, door,
windows, bookcases, books, tables, objects on the tables, parts of your
own body. When someone opens the door and comes into the room, you see
the door swing smoothly open and become stationary in another
configuration. You hear the person speaking; you see the person moving;
you have a sense of recognition of the person. You see distances between
things, relative sizes, colors, brightnesses. You observe that the
person opened the door before, not after, going through it.
All of these perceptions are free of noise. You don't get any sense that
the person's shape is fluctuating among different possible shapes. You
don't experience the distance to the nearest wall as being fuzzy or
variable. You don't see motions as vacillating among possible
alternative trajectories.
It is this world that any theory of perception must explain. This is the
bedrock reality against which all theories must be judged. Somehow, no
matter what is going on at the level of eletronically recorded nerve
impulses, the final result must be this noise-free world of direct
experience. If any model denies the existence of this noise-free world,
then it is simply wrong.
When we look into the mechanics of perception, using different
viewpoints and different observations, we find that perceptions are
apparently conveyed by trains of discrete impulses. But that is
obviously not how the perceptions themselves are experienced. What we
need is some way to combine these trains of impulses so we get a final
form of a perception that is noise-free and smoothly variable, on the
space-time scale of ordinary perception. The story that we get from
looking at impulses is not complete. There must be some measure of
collections of impulses that ends up providing the world that we
actually experience and control. The stochastic phenomena that do exist
must give rise to a smooth and continuous world of esxperience -- just
as the stochastic phenomena that exist in electronics give rise to what
we know as voltages and currents.
We exist and are conscious at the level of the smooth and continuous
world. This, not the deduced stochastic world, is the reality against
which we have to judge all models and theories. Whatever we may propose
at some other level of analysis, it must somehow produce the world that
we actually experience, for that is the only reality we can know.
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Best,
Bill P.