···
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Peter Cariani (960502) --
... there are numerous examples where "firing rates" (itself a very
vague term without any mention of which neurons are involved or
what kinds of time windows are used for the "rate") do not (and in
some cases, cannot) explain the perceptual distinctions that are
made -- where other factors such as temporal discharge patterns and
spike latencies appear to constitute the "signal".
Since rate is simply 1/interval, and changes in firing rate are
certainly "temporal discharge patterns" or changes in spike latencies,
it seems to me that there is no fundamental difference here. If a neural
signal looked upon as a rate of firing changes rapidly as a function of
time, there will of course be changes in the temporal discharge patterns
and spike latencies -- how could it be otherwise? A neural signal
carrying a low-order version of a complex tone of steady pitch, such as
the sound of an oboe, will consist of superimposed harmonics that,
neurally represented, will produce a complex pattern of firing
frequencies or interspike intervals (or neurotransmitter
concentrations), whichever way you want to look at it. But at a higher
level, the identification of the sound as that of an oboe can be
represented as a signal of constant frequency (or interspike interval),
as long as the sound is still that of an oboe. Of course _naming_ the
instrument is a matter for still higher systems.
The representation of pitch is a singularly complex problem because the
range of audio frequencies overlaps the range of neural firing rates
(which could also be described as an overlap of audio periods with the
range of interspike intervals). As far as I know, this problem is unique
to audition, occuring in no other sensory madality. I commend you for
investigating this complex phenomenon, and would be very interested in
seeing anything recent you have discovered about it.
---------------------------------
Next to these problems, those of operationally-defining how to
recognize self-producing sets of signals from some set of
identified and observed signals is trivial. Consider a set of
chemical reactions between substrates A-Z, where some combinations
of substrates produce other substrates, e.g. A + B -> C, and M + O
+ Z -> D + W + F. One can make a directed graph of the reaction
network and using graph-theoretic (or logical entailment)
procedures find those sets of substrates that form closed loops,
i.e. the members of the set through their interactions regenerate
the members of the set.
Sounds useful. Graph theory, however, can represent only the map of the
interconnections -- the dynamics and other quantitative considerations
aren't contained in a map of logical entailment. In biochemical
reactions there are certainly closed loops, but some of them are control
systems and the rest are not. The difference depends on the loop gain.
If the loop gain is less than 1, I would not call the result a control
system even though there is a small amount of negative feedback. A true
biochemical control system probably has to include an enzyme, which can
insert a gain of as much as (or at least) 50,000 into the loop. That is,
a change in the effect of the enzyme on a reaction is reflected (via the
product) back to the enzyme (by, for example, shifting it from the
active to the inactive state) to produce an effect that is 50,000 times
as large as the initial change. But the system is stable. So not all
closed-loop systems have the same properties.
I believe it was Warren McCulloch who first misled cyberneticists
(Proceedings of the 5th Macy Conference) by telling them that a closed
loop (even a negative feedback loop) can't be stable if it has a loop
gain greater than 1. This is something to ponder when considering
biochemical control systems with closed-loop gains in the tens of
thousands.
See Hayashi and Sakamoto (1986), _Dynamic Analysis of Enzyme Systems_,
Springer-Verlag (particularly Chapter 6).
-------------------------------------
How about them optical interferometry telescopes that were in
yesterday's science section of the New York Times? Really
impressive.
Yes, I had seen that in Science, Science News and Sky and Telescope.
Spots on Betelgeuse! Fantastic.
You're going to have to explain, however, why this observation showed up
in this particular post. Is it something about epistemology? I once
asked an astronomer friend why astronomers liked to transform the
almost-plane wavefronts of light that make up the universe into points
and extended objects, by using lenses or curved reflecting surfaces. He
didn't think that was funny.
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Peter Cariani (960502.1200 EST) --
However you want to characterize Hard and Soft accounts, I want to
make it very clear that I have always been very much opposed to the
notion that simply making something more complex confers onto it
special properties.
Roger. I hope the same thing applies to the general notions of re-
entrance or recursion, patterns, and so forth.
"Complexity" and organization are two very different things: one
can have very simple control loops and very complex ones, but what
makes a control loop a control loop, i.e. what gives it its
functional organization is not determined by its degree of
complexity. Isn't this obvious? Let's not conflate these things.
I agree, let's not. I can go on; it's not the re-entrance or recursion
that creates the function called control, nor is it the idea of
feedback, nor is it even the idea of "organization." All those ideas
apply to system which are not control systems as well as those that are,
and hence do not distinguish control from non-control.
Secondly, I am not in any way invoking "magical" processes, andI am
not proposing that "new physical phenomena," in the sense of new
basic properties of matter, are being created by the evolution of
functional organizations that are capable of observation. What does
happen is that the evolution of a particular organization of matter
permits there to be informational operations like "memory" and
"modelling relations" (Pattee, Rosen, Kampis), such that
"observers" are made possible.What does happen is that the
evolution of a particular organization of matter permits there to
be informational operations like "memory" and "modelling relations"
(Pattee, Rosen, Kampis), such that "observers" are made possible. A
rock is not an observer, a cell is a primitive observer, a human a
much more elaborated one.
But that is exactly the step that I find magical. Why should memory make
observers possible? Is a phonograph conscious? Why should "modelling
relations" make consciousness possible? Does the relationship between a
computer model of tracking behavior and the actual behaviour make the
computer conscious? You speak as if we have all agreed on the nature of
the phenomenon that we call "consciousness," but what you are really
doing is saying that whatever the term may mean, it is "nothing but"
memory, modeling relations, and so on. That is not explaining
consciousness; it is reducing the problem to fit the kind of explanation
you prefer. That approach was anticipated some time ago by a fellow
named Procrustes.
Memory and modeling relations may give the observer something to
observe, but how can we say that they ARE the process of observation?
Once you have decided that consciousness is nothing but some set of
particular physical processes, your logic them compels you to suggest
that other examples of similar processes must also entail consciousness
-- even a camcorder has to have a tiny bit of consciousness. But the
basis for such claims is not any evidence of consciousness; it is only
the evidence that similar physical processes are occurring. The
relationship of these processes to consciousness remains, actually,
unknown and putative.
One is not "required" to consider a system as a "control system" in
order to describe its physical workings, and one is not "required"
to consider particle-like properties of light in order to describe
its wave-like properties (interference).
You have it backward, as least as far as PCT is concerned. We did not
start with "control" and from that derive the idea of a control system.
It went the other way. First, there were systems capable of stabilizing
variables outside themselves, maintaining those variables in specific
states despite disturbances tending to alter them. Our first organized
understanding of systems that could behave like this arose out of
engineering and the artifacts built by engineers. What was not generally
understood at first was that the engineers called them "control systems"
because of their (deliberate and intended) resemblance to human beings
carrying out processes commonly called "controlling."
One is not required to consider a system as a control system _unless it
is observed to be controlling something_ -- that is, varying its actions
on the environment in such a way as to stabilize some aspect of that
environment against arbitrary disturbances, and doing so in a way that
depends on sensing the environment. While the term control has been used
in many different ways, in PCT it is used in one and only one way, which
can be technically defined so it can't be confused with any other kind
of organized behavior.
The analogy with the wave-particle complementarity is spurious, because
in fact the behavior of matter can be seen as involving either waves or
particles, depending on how you set up the experiment and analyze it.
This is not true of controlling in the PCT meaning. If you set up an
experiment with control and determine that control is occurring, the
proper analogy is with setting up a pair of slits and observing that
there is interference, which demonstrates the wave nature of matter. But
there is no second way of setting up the behavioral experiment, that I
know of, which will produce a different result, analogous to showing the
particle nature of matter.
In the wave-particle situation, there are two different and mutually
exclusive results obtained: interference patterns, or lack of
interference patterns. This is not a case where there are two competing
explanations of the same phenomenon. There are, in fact, two different
phenomena. This is not just a difference in points of view; one cannot,
simply by changing interpretations, make interference fringes occur when
they are not occurring. It is necessary to change the physical situation
in order to change the phenomenon.
We have a different situation when we are explaining control phenomena.
Here we have a single phenomenon, the stabilization of variables against
disturbances (shorthand for a more complete description). Merely
changing one's perspective (or the word that is used) does not remove
this stabilization, nor (so far) is there any phenomenon that we call
control in which this stabilization does not occur. There are, of
course, other kinds of phenomena which do not entail control, but their
existence does not negate control, and is not an alternative to control.
Does a system whose organization is described as a "control system"
call into being new basic properties of matter? No.
No, not at the lowest level of organization. But there are, as you know,
emergent rules that show up at higher levels, and they can't be reduced
to the rules governing the lower levels. Join an inductor and a
capacitor, and you get rules that are not reducible to the rules
governing either inductors or capacitors. It is possible that
consciousness/awareness/Observing is such an emergent phenomenon. I
don't know. We can easily show HOW resonance emerges from combining
inductors and capacitors (conservation of energy is one way), so we can
prove that true emergence is occurring. But until we can show HOW
consciousness emerges from neural processes, we can't establish the
link.
Might such an organization permit such a material system to become
an "observer", in some very primitive sense? I think so.
Until we can establish HOW consciousness emerges from these lower-level
processes (if it does), the best we can do is to explore the apparent
properties of consciousness, as in the comments by Gary Cziko and John
Burch, above.
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MArtin Taylor (960502) --
Boys with air guns sometimes like to shoot at big shiny balloons full of
light gases 
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Bruce Gregory (960502.1345 EDT) --
The problem, as I see it, is that the receiver (not on the football
field, but in the nervous system) _seems_ to be skirting the edge
of being a homunculus looking at a screen similar to the one in the
stadium and subject to changing perceptions.
In a sense, it is a homunculus. But the hierarchical concept in PCT puts
a different spin on the little man in the head. Since the levels of
perception and control are specialized, as we move up the levels of
neural function, we strip away one layer after another from what is
left. When we get to the logic/program level, for example, there are no
longer any categories, sequences, relationships, events ... intensities.
There are only logical processes involving logical variables, and of
course the processes at higher levels, principles and system concepts.
When we have stripped away ALL the levels in the hierarchy, what we are
left with is either nothing, or the Observer. The Observer does not
itself do ANY of the things that the hierarchy does. So the little man
in the head has been reduced to a point-receiver.
The usual homunculus problem arises because of duplication of function.
We say that there is a perception of a red apple, in the form of neural
signals. But to identify those neural signals as a red apple, we need
another level of perception that knows that these signals are a red
apple, and another to know that the signals in the second level are a
red apple, and so on to infinity. That's the basic little man problem.
In the PCT hierarchy, however, there is one level concerned with
creating neural signals corresponding to objects, the configuration
level. There are no more configuration levels above it. Higher
perceptions are not perceptions of configurations, but of motion, event,
relationship, category, etc.. Each level of perception occurs only once,
and is the ONLY level where variables of its type are represented as
neural signals. So when you consider the whole hierarchy, you have all
the levels of perception that make up experience, each level existing in
only one layer and supporting only one type of perception. The Little
Man in the Head can be nothing less than the whole brain.
If this is a workable picture of the hierarchy, it gives us a hint about
consciousness. In the world of ordinary conscious experience, all these
levels of perception seem to coexist in the same space. We don't
experience any layers; the layers are transparent. At any given time, we
don't experience all the levels or everything in every level. We can
focus down to a very narrow range, or widen the focus to include more
information at more levels. You can look at an electric light bulb and
focus on its intensity, or you can widen your field and appreciate that
it is a symbol for Thomas Edison. In any experience, there are many
levels at which you _could_ experience it consciously, but usually only
a fraction of what is possible to experience is actually noticed
consciously. And there is only a single space of conscious experience.
Also, if the hierarchical concept of perceptions is right, higher-order
perceptions are functions of lower-order perceptual signals. If your
attention is narrowed down, say, to logical or computational aspects of
experience, you could not be having those perceptions unless all the
lower levels of perception were working and providing signals, each
level supplying the required inputs to the level above it (I'm ignoring
imagination). This would be a direct proof that the same perceptual
signals may exist either with or without consciousness of them --
contingent, of course, on the hierarchical idea of perception. And since
focusing attention on any one level makes perceptions of either higher
or lower levels invisible to consciousness, we can show that awareness,
as Rick Marken suggests, receives information only from "below" its
current locus in the hierarchy.
Most of us, including you and Rick, I suspect, would be happier if
the receiver could be modeled by a control system. But happiness
is not always granted us.
Teew Treew. Anyway, a control system needs more than an input function.
We need volition for an output function, but following this paths leads
into the mists -- reference signal? From where? About what?
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Ellery Lanier 960502 --
I was just curious as to whether the two [Powers and Calow] even
had heard of each other.
Powers hadn't heard of Calow. Still haven't read his book, but will try
to get it sent by stagecoach. My work has been anticipated in many ways
by others who wrote after I did.
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Rick Marken (960502.1100) --
Peter Cariani (960502)
Peter asked:
>Where is the "observer"?
I said:
> "Outside" of the neural signals (perceptions) that are observed;
The correct answer is "where is 'where'?" "Whereness" is a learned
concept that exists in the hierarchy of perceptions. "Inside" and
"outside" are learned perceptions. "The hierarchy of perceptions" is a
learned perception . Whatever has been learned has been learned by the
hierarchy; the Observer observes the result.
Or so, to be consistent, it seems.
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Best to all,
Bill P.