What does a blind person see?

What does a blind person see?
perseus
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Posted Apr 14, 2007 - 7:14 AM:
Subject: What does a blind person see?
What does a blind person see? The answer seems obvious, black. However, what happens if that person has been blind from birth. Since they cannot conceive of light can they conceive what it is to have the absence of light? This is similar to comparing the number zero with null, the absence of any number, these are two different things, and surely a blind person from birth experiences null rather than zero?

This question is not purely philosophical since they are people who have been blind from birth and experienced a knock which has allowed them to see. What did they 'see' before the knock?

A closely related question is can they really see anything immediately after the knock, doesn't the visual cortex take time to form connections and make sense of the patterns and colours of light coming in? If so could an older person whose brain capacity for change is limited ever see anything even if the eye and optic nerve were fully restored?
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Posted Apr 14, 2007 - 10:24 AM:

Interesting idea, but how do we experience null?
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Posted Apr 14, 2007 - 2:36 PM:

A blind person can't see anything; no colour. However it depends on your idea of seeing. Someone who has seen then become blind may 'see' but only as their imagination. What they see may be wrong but they might try and imagine what's there. Is that seeing?meh.

I wonder if those that were blind from birth do build up some kind of original imaginary picture of the world.

Thoughts...
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Posted Apr 14, 2007 - 4:09 PM:

I've always thought that a blind person "sees" what I see with regard to magnetic fields. There are some creatures that can see magnetic fields, and since I cannot, I am "blind" in that sense. That however, as you all know, does not feel like anything, to be precise. On the other hand a blind person may have certain parts of his brains that would receive visual data active, and hence perhaps experience more with regard to his blindness than I do with regard to my blindness of magnetic fields.

~M~
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Posted Apr 14, 2007 - 5:04 PM:

Cadrache wrote:
Interesting idea, but how do we experience null?


I would guess we humans 'experience' null sonar and electric field since we have no direct means of experiencing these sensory modes. We cannot start to imagine what it is like to be a bat or fish with those senses.


Edited by perseus on Apr 14, 2007 - 5:10 PM
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Posted Apr 14, 2007 - 5:49 PM:

perseus wrote:
What does a blind person see? The answer seems obvious, black. However, what happens if that person has been blind from birth. Since they cannot conceive of light can they conceive what it is to have the absence of light? This is similar to comparing the number zero with null, the absence of any number, these are two different things, and surely a blind person from birth experiences null rather than zero?

This question is not purely philosophical since they are people who have been blind from birth and experienced a knock which has allowed them to see. What did they 'see' before the knock?

A closely related question is can they really see anything immediately after the knock, doesn't the visual cortex take time to form connections and make sense of the patterns and colours of light coming in? If so could an older person whose brain capacity for change is limited ever see anything even if the eye and optic nerve were fully restored?


I would say that a completely blind person doesn't see anything. They're blind. Most people that are clinically blind aren't 100% blind, they still can see shapes and whatnot. However if someone is 100% blind, perhaps their cornias are not attached or something, they simply wouldn't see anything. Their brain would not be recieving visual information of any kind.
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Posted Apr 15, 2007 - 9:43 PM:

Hmm. If you were to cut out both a mans eyes, would he be able to see the absence of color (black, the absence of light)? Would he be able to see the absence of the absence of color? This means that he can see nothing on the color wheel, and nothing NOT on the color wheel (black). Therefor, if he cannot see (all colors) + (black), then must he see nothing in a more basic sense, one that includes light and other mediums?

If you cut both a man's ears, can he hear silence? If you cut off a mans lips, can he taste the absence of taste?

My answer is, he would simply not see anything, INCLUDING nothing. Lets say an organism is born without ears. They cannot hear silence. They cannot hear sound. Therefor, they cannot hear (sound + the absence of sound), so therefor they must not have the "sense" of sound at all, including all it (sound) offers, even when the value of what it offers is zero.

So what does a "truly" blind man see? He can't see anything, for the simple fact that he has no sense of sight.
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Posted Apr 15, 2007 - 11:54 PM:

What does a blind person see?


What is the point in asking what a blind man sees when he cannot see in the first place? confused

I also don't think there is any point in asking "what a blind mind sees" in any "visual sense"...
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Posted Apr 16, 2007 - 2:21 AM:

The Flood wrote:

My answer is, he would simply not see anything, INCLUDING nothing. Lets say an organism is born without ears. They cannot hear silence. They cannot hear sound. Therefor, they cannot hear (sound + the absence of sound), so therefor they must not have the "sense" of sound at all, including all it (sound) offers, even when the value of what it offers is zero.

So what does a "truly" blind man see? He can't see anything, for the simple fact that he has no sense of sight.


This is similar to the point I was getting at, but if true (and I am not convinced) this only applies to someone born blind, not someone who has become blind. In the latter case the visual cortex would be developed and will be expecting an input in which case they would experience the sense of black that is an absence of light similar to a sighted person being in a totally dark room. They could also internally generate the sense of white and coloured sight in a dream or hallucination.

On the other hand even someone born blind may have a partially developed visual cortex due to evolutionary development so perhaps even they see black, there must be a definitive answer from people who have become sighted.

hyena in petticoat said: What is the point in asking what a blind man sees when he cannot see in the first place? I assume you have understood the question. Perhaps the question was posed incorrectly, what does a blind person sense in their visual cortex.

Let's put the question another way. Consider an animal which has evolved in a cave or deep sea, they would not have the sense of seeing therfore they could not experience black. This is fundamentally different to someone who has become blind who can.
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Posted Apr 16, 2007 - 2:36 AM:

Perseus,

I still don't see how we can talk about "what a blind man sees" in any visual sense.

I also find it difficult to suppose/ assume that the blind man (from birth), would be "able to" conjure up any images in his head about certain things since, I think (I'm not sure) that the reason we are able to conjure up any images in our head is that we have been able to see things which we can base these images upon in one way or another.

I can't provide anything scientific though.
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