Artificial Sight

Glen M. Sizemore gmsizemore at triad.rr.com
Sat Aug 4 07:46:41 EST 2001


MJ: Hi Glen,

In response to your last post, first let me clarify
something: When I
used the word "semantic" I was absolutley -NOT-
implying triviality.
What I was trying to do is show that the
disagreement occurred due to
our different usage of the same word (which it
clearly does). In my
opinion, such semantic differences are not trivial.
But generally a
discussion can't proceed very far if the participants
are speaking in
different languages, so I think it's important to at
least identify
places where different definitions can be an
impediment to further
discussion.

I do not think your point of view is trivial. Nor do I
think the
subject of sight is trivial, whether approached biophysically,
psychophysically or psyhologically.

GS: The phrase "semantic
argument" is usually preceded by "merely a..."
Obviously, I disagree with this view. And I'm
not sure that it doesn't characterize your
position, despite what you have written
above.

MJ: Next:

> GS: *I* am not defining "message." I realize that I
> don't have that luxury. Or rather, *I* realize that to
> take such license in these circumstances is nonsense
> (see my comment on operationism). Even at this
> point, I knew what you were about to say, right
> down to citing Shannon. The problem is - and
> speaking somewhat colloquially - that you can not
> escape the meanings of colloquial terms by simply
> redefining them to meet your philosophical needs.
> Specifically, the ordinary usage of "information" and
> "message" implies a PERSON "receiving," if not
> both "receiving and sending." Ironically, even
> though this aspect of the colloquial meaning is what
> Shannon sought to eliminate by defining
> "information" in physical terms, it is just that aspect
> that allows positions like yours.


MJ: I don't think Shannon was interested in
eliminating colloquial
meanings. Neither am I. However, there simply is no
such thing as "the
colloquial meaning" for any particular word, because
every speaker has
a slightly different meaning in mind. Colloquial
meanings are
generally ambiguous.



In science, however, meanings need to be more
reproducible than that.
So people need to be clear about specific definitions.
That is one
reason why different scientific definitions of
information exist
(i.e., Mutual Information, Conditional Information, Fisher
Information, etc) even within the same discipline. It's
not that any
one of them is "better" or more "correct". It's simply
that they mean
different things, but do so unambiguously.

Nobody wants to get rid of colloquial meanings. But
just try building
a communications network (or a brain) with nothing
but colloquial
meanings to go on. It won't work. On the other
hand, given one halfway
decent equation, where the symbols are -
unambiguously- defined, one
can understand the workings of a system very
precisely. -Within- the
context of the definition that was applied during the analysis.
Obviously, applying Shannon information measures
to vision probably
won't satisfy many philosophers or psychologists.
But that is not the
point of using that definition. The point is to arrive
at -some sort
of framework- where the working of the system
'makes sense' (i.e., is
internally consistent). I have given one example of
such an analysis,
in which Shannon Information was used to make
quantitatively testable
predictions about visual processing, which were
accurate within a
reasonable margin of error that would be acceptable
to most
biologists. Can you give a similar example in which colloquial
definitions yield similar levels of quantitative
accuracy?

GS: Actually, I advocate eliminating colloquial
terms in science. This was, in part, the impetus
behind my post. Again, one does not escape the
colloquial meanings of terms by simply redefining
them. Thus, even though you define particular
terms, their usage "forges" the activities of scientists
in ways that reflect colloquial usage.  That wasn't
my only point, though. Part of it was a critique of
the notion that any term is OK as long as it "can be
defined operationally." The problem is, of course,
that no terms are thereby eliminated. As Skinner
pointed out in 1945, the main use of "operational
definitions" was to smuggle specious terms back
into psychology. Indeed, and I know this is a
difficult point, the acceptability of terms like
"representation," "computation," and "information,"
resides partly in the fact that the terms carry with
them the colloquial "meanings," DESPITE THE
FACT THAT THEIR OPERATIONAL
DEFINITIONS SPECIFICALLY OMIT THESE
ASPECTS. Thus, Shannon's information has
nothing about it that smacks of the sorts of
philosophical problems surrounding "mental" terms,
yet it can only thrive because it appears to get at the
traditional issues while eliminating their
philosophical difficulties. See?

Because of this behavioral fact, conceptual analysis
is of great importance, and an important step in
conceptual analyses is to examine concepts in light
of their colloquial meanings as given by the
"grammar of their use."

> After all, what is on
> the receiving end of a telephone? No, not the
> "receiver".....it is the person. What comes out of a
> telephone "receiver" is not "interpreted" by the
> telephone receiver - it is interpreted by the person.

MJ: No. It -may- be interpreted by a person, but it
doesn't have to be.
Maybe a better (but almost identical) example is the
packet-switching
that goes on during internet communications. What
is on the receiving
end of the request that your newsposter program
sends to the
newsserver? Is it a person? No. It is a newsserver
daemon running on
the server. Does it know that your intended message
to me is that I am
"transparently vacuous"? No. What it knows is that
your client sent a
specific -message- in TCP/IP, that requested a
certain set of actions
(behaviors), with certain instructions for how the
piggybacked usenet
post should be catalogued, displayed and stored.
There are no people
involved here at all. My opinion is that something
similar goes on at
many stages in the brain.

GS: Again, this is metaphor. The news server
doesn't do anything like what a person does when
he or she is said to interpret. Now, mind you (and
this is extremely important), I am not offering
"interpret" as a useful scientific term (I hold that it is
not).

Say we have four telephone handsets and we
"transmit a message" via one (A) and "receive it
with another (B). Now say we put the mouthpiece
of a third (C) next to receiver of B. Now the
message is "received" by D. Has there been any
"interpretation?" Or, more to the point of using
effective concepts, has any part or all of the system
"behaved" in a sense that is meaningful to the
behavior of organisms?" Later, you want to instruct
me on postural reflexes and how they validate your
(and, of course, most everyone else's) view. But
your internet and reflex examples are both equally
silly.

MJ: Now ultimately, in order to satisfy
psychologists, one must come up
with an explanation of how -we- (i.e., whatever it is
that we mean by
our consciousness) finally interpret the result of all
the lower level
processing. However, that highest level
interpretation is quite
obviously -optional-. The lower level messages and
their lower level
interpretation goes on constantly in our brains
without ever making
its way to the top where a "person" re-interprets it.
In fact, it goes
on all the time in organisms in which we would
probably deny that
there is any "person" home at all. Or do you not
think that clams can
see?

GS: It should be clear, now,  that this statement has
nothing to do with the points I am making. I have
never made any of the points that you attribute to
me. It is utter nonsense to say that the fact that
"clams can see" (if indeed they can) somehow is
antithetical to my arguments, and this would be true
without any of the clarification I have provided
above (as well as what follows). Plus, obviously you
have misunderstood my points on every level
possible. As I pointed out, the terms you use will
"carry their colloquial meanings with them" (in the
sense of controlling the behavior of scientists - I
know you don't follow this much, but I can't fix
your misconceptions all at once) despite the fact that
you state a particular definition. Also, the definitions
only seem profound BECAUSE they carry those
meanings.

This is not to say, incidentally, that Shannon's
contribution was not important - it just doesn't have
anything much to do with behavior.


> Even if we refer to the activity of sensory organs
> and "the things they are connected to" as
> transducing a message (which is itself nonsense),
> there is nothing to "interpret it as such" unless one
> wants to posit an homunculus, albeit implicitly. See?
> You want to say your are considering only the
> analog of a telephone (both transmitter and receiver)
> but the physics of the telephone are sterile with
> respect to the issues that should matter to
> psychology and behavioral neurobiology.

MJ: Like I said, I'm rather less concerned with the
"issues that should
matter psychology and behavioral neurobiology"
than I am with
understanding how nervous systems process
information. Last time I
checked, most of the real progress in that area had
been made in
blowflies, crickets, squids, salamanders and crabs.
Some has also been
done in cats, rats and monkeys, but less progress has
been made in
those animals. What is the state of the art in blowfly psychology
these days?

GS: This all misses the point. Right? Your claim to
be uninterested in "psychology and behavioral
neurobiology" is telling. And it is very, very, naive.
There is nothing wrong with neurophysiology per se,
but we are clearly not talking about neurophysiology
as divorced from behavior when we are talking
about "seeing." Or, at least, that's what I am arguing.


>You want to eliminate
> all that is psychological but you want your telephone
> analog to address psychological issues.

MJ: God, that's the last thing I want. I want my
telephone to shut up and
do its job, which is to act as a reliable information
channel, plus
implement whatever source coding and channel
coding algorithms that
are most likely to get the message from point A to
point B with
minimal distortion. That's pretty much exactly what i
want from my
visual system too. If you want to call understanding
how that all
happens "psychology", that's your prerogative.

GS: This misses the point. Right? My point was that
"seeing" MUST be more than COPYING. Thus the
statement: "If you want to call understanding how
that all
happens 'psychology', that's your prerogative"
makes me think that you have not carefully
considered my points. Other than that, you are
simply repeating your argument, and I have no
trouble understanding you argument. Nope. None at
all. I have seen it, literally, thousands of times.



> GS: This is all beside the point. First,
> "communication channel" begs the same issue. So
> does "information," despite the fact that
> "'information' may be given a particular
> [mathematical no less!] definition" as in Information
> Theory. Since you have defined "information," how
> could it not be true that "The signals passing over
> the optic nerve to the thalamus and cortex are certainly
> 'messages' in the information theoretic sense." It is
> ironic that you raise the Stanley et al paper since it
is
> Stanley et al that do the interpreting! Or are you
> saying that something in the brain acts as Stanley et
> al!
>

MJ: Well, we can define things so that internally
consistent theories can
be formulated, and then test them against
experimental observations.
When I see an example of success with that tactic,
I'd call it
"predicyion". Apparently, you'd call it "circular
reasoning".

GS: Once again, your reply seems to be largely
irrelevant to what I have written. Can you say why?
Hint: (conceptual analyses). Other than that, my first
inclination is to launch into a tirade on what a
pedestrian view of science this expresses. Sorry,
there is no way to be gentle with someone when
they presume to lecture you on science by saying
that "science tests internally consistent theories,"
especially since this is only one thing that science
does, even if it often has spectacular results.


MJ: Most people wouldn't claim that the brain acts
as the algorithm
implemented in Stanley et all (although I and many
other people would
probably admit that, yes, it should be considered as a
possibility
requiring further testing). Stanley et all are -not-
really doing any
interpreting. They're simply crunching some
spiketrains through a
particular algorithm, and then showing us the
results, which to me
look quite a bit like the visual stimulus they showed
the cat. So I
guess -I'm- doing the interpreting, or at least the
evaluation.

GS: Don't be abstruse. They recognize it as
"the stimulus" and they publish
the picture.

> GS: But this is transparently vacuous. All it does is
> assert that somehow neurobiology is relevant to the
> functioning of the organism. Oh yeah.....it also
> asserts that part of what neurobiology does is to
> make (and no doubt store) copies of the world. So,
> the world is taken into the brain on the analogy of
> the telephone. But once there, you cannot say how
> this copied world "brings about actions." This is the
> weakness of mainstream cognitive psychology; the
> making of copies cannot contain anything of import
> to behavior without something to turn copies into
> behavior. But wherever and whatever the analog of
> the telephone receiver is "in the brain" it can only be
> connected up with more stuff which can also be
> given the same physical description. So how is it that
> a copy "comes out as behavior?"


MJ: <sigh>

GS: "<sigh>"???!!!


MJ: Ok. Here's a simple example. You have a nerve
cell in your leg that
connects on one side to your kneecap and on the
other side to another
nerve cell. Cell #2 connects to a muscle attached to
your kneecap. You
thwak your kneecap with a little rubber mallet. This activates
mechanoreceptors in cell #1, causing it to fire
spikes. The spikes
travel up the axon, releasing glutamate onto cell #2.
Cell #2 has
glutamate receptors that respond by causing spikes
in cell#2, that
travel down its axon, releasing acetylcholine onto
the muscle. The
muscle twitches, moving your leg. Familiar knee-
jerk response.

This is how the copy "comes out as behaviour". By
the way, it's not
just a copy. It's a series of multiple trasnformations,
each serving
a different role.

GS: Here a stimulus has produced a simple
unconditioned response. The stimulus was in no way
copied (or transformed for that matter) and the
whole process can be described without recourse to
saying that "force is encoded by frequency" or some
such.  I would think that this example would raise
embarrassing issues for you. What does the
"interpreting" here? The muscle? Everything
efferent? If so, is that a general rule? Everything
afferent is the "stimulus representation" and
everything efferent is "interpretation?" Or is this
example devoid of interpretation? More importantly,
do you really mean to imply that all of behavior is
just a generalization of a postural reflex? and so
forth.

And there is much about your assertion that is sort
of funny. Your reference to multiple transformations
is perhaps more apropos to physical systems in
which energy of one sort is transferred through a
system, especially when it is changed in form - as in
a steam engine for example. Now that raises
interesting questions! Is the fire sending a message
to the piston? Are the wheels of the steam
locomotive interpreting this message? What about
systems in which the energy doesn't change form?
Am I sending a message to the rock when I lift it
with a lever? No doubt everything to the left of the
fulcrum does the interpretation (sigh). Or maybe,
and if I were you I would make this argument, your
kind of "explanation" only comes into play when the
system cannot be understood either in terms of the
transference or transformation of energy?
Yeah.....that's it! You could argue that only when
these conditions do not hold do you have the kind of
system shown by the unconditioned reflex. In a way
that's true......but it still doesn't make your position
any more cogent.


> GS: Again, the telephone receiver does not interpret.
> Information Theory is of little or no use to
> behavioral neurobiology because it has nothing to do
> with behavior.

MJ: Information theory was not formulated to be of
use to behavioral
neurobiology or behaviour. It was formulated to
understand the
movement and transformation of information in the
presence of noise.
But if behavioral neurobiology can't see any use for
something like
that, it has bigger problems that worrying about its
definitions.

GS: You are certainly right that "Information theory
was not formulated to be of use to behavioral
neurobiology or behaviour."


> GS: I have already pointed out that this notion is
> silly and distracting.


MJ: Yeah. Don't forget "pernicious" and "vacuous".

GS: Oh! Thanks for reminding me Matt!


> MJ: What's the alternative? The only alternative is
> that seeing takes
> place -without- the transmission of information
> between the eyes and
> the brain.
>
> GS: Yes, it takes place without "information" except
> when "information" is defined in such a way as to be
> devoid of import to the analysis of behavior or its
> potential reduction to nuerobiological events. In
> such a case, it is no explanation at all.


MJ: Well, I think the link between information
theory and neurobiological
events is crystal clear in the examples we've been
discussing. The
subject of the analysis is literally the spiketrains of
neurons (which
are, um, neurobiological events). As for it's import
for the analysis
of behavior, well, it -is- behavior. In exactly the
same way that
locomotion is behavior (in fact, many of the same
molecules are
involved). Unless you mean something else
(something 'special') when
you say behavior...

GS: Of course I mean something special when I say
behavior. The "behavior" of a telephone has little to
do with the behavior of organisms.


MJ: Have a nice day,

Matt

GS: Au revoir,

Glen







"Matt Jones" <jonesmat at physiology.wisc.edu> wrote in message
news:b86268d4.0107300914.46d7a2b9 at posting.google.com...
> Hi Glen,






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