Re: Consciousness revisited


"Curt Welch" <curt@xxxxxxxx> wrote in message
news:20110615002854.117$oq@xxxxxxxxxxxxxxxxx
Giga2 <justholme@xxxxxxxxx> wrote:
On Jun 14, 7:07=A0am, casey <jgkjca...@xxxxxxxxxxxx> wrote:
On Jun 14, 2:39 pm, Gary Forbis <forbisga...@xxxxxxx> wrote:

On Jun 8, 5:16 am, Don Stockbauer <donstockba...@xxxxxxxxxxx> wrote:

I'm sorry it came to this, but we can't let a valuable resource
like comp.ai.philosophy go moribund.

It seems ai has been reduced to a set of technologies.
Does one really ask for the philosophy of hammers or wrenches?

Concerning the issues of consciousness the adage "Of that which
nothing can be said, say nothing" applies. =A0None the less we talk
about it all the time. =A0Yes, we includes me.

One of my favorite subjects that we a chipping away at.

http://www.susanblackmore.co.uk/journalism/ns02.htm

Very interesting and well explained article! I'm not sure I see how it
*would* make the 'hard problem' easier if consciousness is really
fleeting, and conscious experience is created in retrospect rather
than on the fly. It has been obvious for some time that brain
processes are necessary for conscious experience and naturally they
take time, so we are always aware of the past rather that the,
presumably, physical present. Conscious experience probably must be a
complex simulation generated from *data* acquired by the senses rather
than any direct window from the world into the mind, it is indirect,
and this also is fairly well accepted in psychology and even
philosophy. So what exactly does this retrospective aspect contribute
to the ease of understanding *how* we can experience this internal
simulation at all (let alone why from an evolutionary pov!)?


On change blindness Susan Blackmore writes:

"The idea is that as we move our eyes about, we build
up an even better picture, and this picture is what
we consciously see. But these experiments show that
this way of thinking about vision has to be false."

--------------------------------------------------

I disagree with this. While viewing these change
blindness examples I find I eventually spot the
changes and from then on I can always spot them
in the same examples so I am building up a better
description of the picture over time.

Yep, as usual in psychology she makes the jump from 'on average' to
'always', wrongly. In most of these experiments a small percentage of
people do see the changes. Presumably they have largely similar visual
systems, at least in their broad function, so must be taken into
account. Very common mistake in psychology this, especially if the
psychologist themselves is not in the small minority.

I don't see a mistake.


It happens a lot.

The fact that most people don't instantly seen the change is the proof.
The fact that a small minority can is totally irrelevant to the point she
is making.

So do they have a different visual system then?


The point she is making is that the theory we have a complete "image"
stored in our brain which is added to piece by piece (as if it were being
painted), can't be valid, because if we had such an image in our head, we
would instantly notice the change the moment we looked at the part of the
picture that had changed.

Some do.


It only takes ONE example of someone not being able to _instantly_ spot
the
change to show the hypothesis invalid and that's the point she is making.
Not only do we have one example (which is all that is needed), MOST people
won't instantly see it.

One example could just an outlier, someone with an unusual system perhaps,
or they were just paying attention to correct part of the field by chance
etc. So no that would not provide much evidence of anything.

In this case IIRC it is between 5-10% see the change. That is a significant
minority presumably with a very similar visual system to everyone else. So
this experiment doesn't give us any general information or evidence really,
if just tells us an average.


Also building up a picture doesn't have to mean
building up *this* current picture it can mean
building up a set of expectations based on past
experiences.

What the brain cannot do, and this is also true
for any machine vision, is extract and deal with
all the detail in one go. Although we can see
that a table is covered in objects in one go it
takes time to build up a description of all the
objects that are actually there. Before that is
done the obects could change or be moved and we
would be none the wiser and nor would a program
doing machine vision.

That makes sense, computing processes take time!

Well, the problem at hand is that there are multiple processes at work
here. Perception happens very quickly in the brain, in what is basically
a
single pass (massively parallel) through the system from sensors to
effectors in a path that passes though very few neurons (4 ot 6 or
something I think). This sort of single-pass is the "one go" I think John
is talking about. The brain is able to determine a great deal in that
"one
go".

But the system is also using this flow of perceptions, to generate a flow
of actions. Those action choices are based on recent past perceptions.

One of the very powerful behaviors we humans have, is the generation of
speech. So we see a table with stuff on it, and we quickly perceive lots
of major and important facts about it, like "key on flat surface". But
then, in response to that, and everything else happening to us, we tend to
constantly generate internal language (or pre-language) beahviors in our
brain. So the key shaped visual object becomes "my car key" (a language
concept in our brain).

But that generation of these language concepts tend to happen at about the
same speed we have learned speak. It takes time to move your mouth to
make
words, and we have learned to generate words at a similar rate, even when
we are not moving our mouth.

The activation of these language concepts takes time because talking takes
time. It's a behavior that just takes times.

But as these visual and auditory sensations stimulate our language
center,
we will at the same time, generate a strong of language concepts in
response to it. And those language concepts trigger other language
concepts, which adds to our total perception of our environment. The "key
shaped object on flat service" that might be extracted by the perception
system in a single pass, becomes "my car keys sitting on the far corner of
the kitchen table" after it's stimulated the language centers of things
like "car keys" and "kitchen table".

So even though the core perception system is very fast, and is massively
parallel, our language behavior is slow and sequential, because that's how
we are forced to talk. But since that language behaviors creates deeper
understanding and perception for us as it "rolls out" of our brain, that
level of understanding is always slow and takes time to "build up". But
it's not because the brain is intrinsically that slow or limited in
"compute power", but because the behavior those internal circuits are
built
to drive (moving our lips to talk) is physically limited by the speed at
which we can talk.

At least that's how I see it.

Actually visual processing is a very intense process in the brain. It is not
the 'digital-camera-model' that you seem to be envisioning here. It is so
intense that the brain has evolved to take as many shortcuts as it can to
build-up this visual picture of the world, to save time and energy. In fact
there are thought to be two systems, a quick low resolution system (which is
what you use to close your eye before something flies into it, sometimes)
and the full colour, full resolution system that is generally associated
with consciousness. Various visual illusions can be used to show these
tricks and short cuts for what they are. Many people do not realise there is
a blindspot in each eye where the optic nerve goes through the retina, this
information is filled in on-the-fly by the brain on a best-guess basis
(again there are many blind-spot tests you can do online).
As far as language and conceptualisation goes again you seem to be invoking
a very simplified computer-like model of the brain processes here. It is
somewhat more complicated and multi-leveled than this. We know there are
what is called 'feature-maps' created by the brain related to the visual
field. These would include a map of colours, round or straight edged shapes,
symbols, things that are moving etc etc. All these maps are intergrated
eventually into the simulation that we actually perceive. We do not perceive
the world in any direct way. However our simulation is much more useful that
any possible direct perception, just like a radar screen is more useful than
just looking out the window very often.


.

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