Re: Perceptual symbol systems

From: dan michaels (feedbackdroids_at_yahoo.com)
Date: 08/11/04 

Date: 11 Aug 2004 11:01:25 -0700

Traveler <traveler@nospam.com> wrote in message news:<tf1jh09cfr6bevobdtokbu98lm2mc7v2lh@4ax.com>...
> In article <8d8494cf.0408101814.3bc29230@posting.google.com>,
> feedbackdroids@yahoo.com (dan michaels) wrote:
>
> >Traveler <traveler@nospam.com> wrote in message news:<i4jfh0tg5dqnm16ourmo8s7fol84chbneh@4ax.com>...
> >
> >
> >> There is very little in the brain that is related to the world around
> >> us when we are born.
> >
> >
> >One wonders where did the 30+ visual areas in the cortex come from,
> >and why are they interconnected via 1100+ pathways. Why are there edge
> >detectors, movement detectors, color detectors, shape/blob detectors,
> >orientation detectors, binocular disparity detectors, on and on?
>
> What makes you think any of it has to do with our particular
> environment? Certainly it has to do with the design of the eye which
> is based on the physics of light at certain wavelengths and the
> refraction index of the lens. And it's true that the visual cortex is
> genetically designed to recognize edges, lines directions, etc... But
> all this stuff is just generic visual sensory capabilities. The eye
> and the visual cortex have nothing to do with the actual things that
> you look at. That is to say, they could not care less where you set
> you gaze: animals, trees, people, stars, rivers, rocks or what have
> you.

Well, in fact, that is the point. There is a reason we have those
particular 30+ cortical centers that each perform more or less
specific types of processing on the incoming visual information.
Natural selection selected for those particular processing types
because the information they provided to the organism enhanced
survival. The information selected for was common and repeatedly found
in the environment the organisms evolved within. Trees have vertical
edges, stones are blobs, other animals [predators/etc] move, all have
colors, objects close in have larger parallax differences than those
further away, on and on. The visual system organization didn't just
happen, it happened for a reason. The reason they're coded into the
genes is because they help the organism survive in the environment is
evolved into. If they didn't intimately help survival in the real
world, then the organisms would have gone extinct long ago.

Many of these centers exist in other mammals, but apparently humans
have more types. From an evolutionary perspective, these are all
basically outgrowths and reuse of processing centers which exist in
vertebrates lower than mammals, such as amphibians and reptiles; but
as mammals evolved, the processing became less specific and more
general, which allowed new species to appear. Supposedly objects that
don't move are invisible to frogs - frog survival apparently isn't
enhanced by being able to recognize a tree or a rock, although this
idea does seem strange. Apparently frogs don't move fast enuf that
they need to recognize a tree prior to running into it. Whatever.
Animals that move fast need to be able to "predict future" - as
Dennett says - so evolution gave them the necessary visual centers -
ability to perceive binocular parallax, etc.

It's for all of these reasons that I say our perceptual systems give
us a "close-enough" internal representation of the outside world. We
have to learn the names for objects, etc, and we have to learn as
babies to distinquish object from background, and other
characteristics of the physical world, but this would not be very
effective if we didn't posses those 30+ visual centers provided by
evolutionary processes.

As babies, we learn to recognize the objects around us. The
> visual system is extremely general. Note, however, that recognition is
> mostly learned in the hippocampus, assuming, of course, that I
> understand this stuff correctly.
>
> Having said that, this is not entirely true of most animals. It is
> known that some animals (e.g. some species of birds) are born with the
> ability to recognize their predators. Most predators are born knowing
> what their preys look and smell like. But this information is not in
> the visual cortex but in hippocampal memory.

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