[Martin Taylor 2010.12.10.09.29]
[From Bjorn Simonsen (2010.
12.10, 10:50 EU ST)]
[Martin Taylor 2010.12.09.17.39]
>My question here is:
“Where are the acceleration signals”? Do you find them at
the
>levels level seven, eight and nine which pertain
rational processing processes?.
>No. Far below that. Perhaps even in the retina. When you
are at levels relating to the
>rational processing processes, the inputs are usually
categorical, yes-no, this-or-that,
>sort of thing. It's hard to "rationally" perceive a smooth
acceleration! You can deduce
>that a perceived object accelerated if you see only
flashes of it passing gaps in a fence,
>but that doesn't feel the same as perceiving an object
accelerate that you can see clearly.
Yes, also I think the (about)
three lowest levels are in the retina or very close.
You say that we can "deduce that
a perceived object accelerated if we see flashes of it passing
gaps in a fence". I read the word “deduce” as to infer from a
general principle. And this “deducing” is not environmental
variables that are transformed to perceptual signals at level
one.
Yes, that's what I meant. When you don't see the car as being in
continuous motion because of the fence, you don’t perceive the
acceleration, and you have to use a rational analysis to deduce that
it must have been accelerating.
I will try to explain the way I
see it.
When I see a car start from
velocity zero and increase the velocity, the environmental
variables representing the movement of the car is experienced
as neural signals in our brain. I may agree that I experience
an increasing velocity, but I don’t experience what is causing
the increasing velocity.
Right. All control units have the same limitation. They don't see
the cause of a disturbance, or indeed the cause of any change in the
perceptual signal. Some other perceiving system, perhaps part of a
different control loop, may see what causes the change in perception
of the first loop, but the loop whose perceptual value is changing
sees only that perceptual value.
So "you" may actually see what is causing the increasing velocity.
Perhaps you see that someone is pushing the car to try to get it
started (it must be a very old car :-)), or perhaps the car is
running away down a steep hill with someone chasing it. But the
perception of the acceleration is very different from the perception
of the cause of the acceleration.
I am neither experiencing the
rules nor the mathematics that describe the velocity
increasing.
I have learned theories of
physics that describe these mathematical rules. And they exist
in form of neural signals other places in my brain. As long as
these theories explain what I see, when I se the car
increasing it’s velocity, the theories are good enough for me.
Right. You don't need the theories in order to make the perception.
It took a Newton to develop a theory that works. Aristotle couldn’t
do so, so why should we expect any ordinary person to be able to?
But ordinary people can perceive that objects accelerate.
They are mental constructs that
help me to explain what I see. I think Bill once told you that
the real, real world does not operate by laws and principles.
The laws and principles are made by our brains to explain what
we perceive.
Bill doesn't know that the real real world doesn't operate by laws
and principles. Wolfram thinks it does. What Bill does know is that
we don’t know and probably can’t ever know whether it does. The laws
and principles that we use to explain the world are indeed made by
our brains to explain what we perceive. Some of those are private,
some are public and are called “Science”.
>If you perceive "acceleration", it is because you have
some perceptual function that
>incorporates inputs that are
velocities or positions at different times. Perhaps there
>are only two inputs, one being velocity as near "now" as
is allowed by the sensors and
>signal paths, and the other being velocity delayed from
when it was initially perceived.
>Perhaps there are a whole lot of inputs that are
velocities at a series of different delays.
>Perhaps the inputs are positions at earlier times, and not
velocities at all. In that case,
>you would need three at least in order to perceive
acceleration. Whatever the velocity
>and/or position inputs, the perceptual function would
provide a single value as its output.
>In the case where the inputs are two velocities, that
value might be the difference between
>the inputs, for example.
The way I see it is:
If I perceive "acceleration" it
is because I experience something increasing it’s velocity.
Right. The way you do that has to be something like what I described
in the quote. Without a comparison between at least two velocities
you couldn’t tell that the velocity changes.
I describe what I perceive
expressing different physical laws and principles.
I am sorry I don't understand how
you get the word “acceleration” by looking at something
increasing it’s velocity.
You don't get a word by looking at something. You get a word by
agreement among people. I may start with: when I say “bejumplebug”
it looks like that-there, and you say do you mean “this-here is a
bejumplebig”, and I say “No, not this-here but that-over-there”
until you both agree what it is like to experience a bejumplebug.
But of course we can never really know if we experience the same
thing when either of us says we see a bejumplebug.
So I don't get any word, "acceleration" or "bejumplebug" by looking
at something increasing its velocity. I get a perceptual impression,
and it’s apparently the same impression that other people get,
because when I say something like “did you see that accelerating”
when I saw it accelerating, another person is likely to say “Yes, it
sure did!” or “No, it just kept moving at the same pace”, not “what
do you mean, accelerating?” That suggests that we have a similar
feeling for a perception that we label “acceleration”.
You can ask the same question about "red". Nobody can prove that we
see the same thing when we see something I would call “red”. All we
can say is that most of the time when I call something “red”, the
person I am talking to will agree that they also would call it
“red”. I can’t say the same about “puce”, because I’m never sure
what colours count as “puce” (in my group in grad school we had a
standing joke about “puce”: everything we saw was “off-blue puce” or
“off-green puce” or “off-black puce” … because none of us knew
what colour was supposed to be “puce”). But most people do know what
it looks like when something is what we call “red” or does what we
label “accelerate”. So it would seem that most people do experience
some perception that varies with the rate at which velocity changes.
Does this address your issue? I believe that we it the same way, but
that language is getting in the way of an agreement.
Martin
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On 2010/12/10 4:50 AM, Bjorn wrote:
