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trendal
J♠


Registered: 04/17/01
Posts: 20,815
Loc: Ontario, Canada
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"Seeing" without actually seeing...
#5933848 - 08/05/06 07:02 AM (17 years, 5 months ago) |
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I was watching a docu about the human brain last night, and it spoke of an interesting case of brain damage.
A man received brain damage to a SMALL portion of his visual cortex. The damage was localized to that section, so the rest of his brain continues to work perfectly fine.
The result of the damage is that he can't see ANYTHING out of his left eye - it appears, to him, that he is blind in his left eye.
However, during an eye-exam his doctor noticed that he could still "guess" which way an object was moving through the field of view of his left eye - even though he couldn't "see" the object at all!
They could take a laser pointer and move it across the wall in his LEFT field of vision - so he couldn't see the dot at all with his right eye - and he can still "guess" which way the dot is moving with an accuracy of something like 98% - that is way above random chance.
So, the implications: he isn't actually "blind" at all! His left eye still sees perfectly fine, and his brain is still processing the information from his left eye....the only problem is that he isn't consciously aware of seeing anything!
How does this information apply to your views of consciousness and the human mind?
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Once, men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them.
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redgreenvines
irregular verb


Registered: 04/08/04
Posts: 37,532
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Re: "Seeing" without actually seeing... [Re: trendal]
#5933862 - 08/05/06 07:23 AM (17 years, 5 months ago) |
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at least 2 things that normally happen are not happenning. (1)fragments of vision from the fovea are not being collected and (2) the fragments are not being zipped together into an image from the left eye.
However a visual field still exists sensitve on a peripheral (non foveal (no focussing or scanning)) basis, and some integration of this peripheral or nonspecific visual activity is happenning in a preperceptual and non-reconstituted way; this renders just enough information to provide the barest suggestions of movement or direction, but no detail.
what this should suggest is that the primary vision is handled in a basic way as well as in a processed way. the basic way is what he is left with and the processed way includes the collecting of focussed subframes, and the repositionment of them onto a larger "reconstitution field of visual cortex" (a visual awareness screen in which 3-d modelling is prepared from image fragments (from both eyes)).
if the foveal collection area (quite small) is nonfunctional it will not relay anything into the continuous collection process for repositionment and alignment and zipping togehter of integrated 3-d scenes from which objects can be matched into the memory storehouse etc.
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bobjones
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Registered: 10/12/05
Posts: 999
Loc: Tx
Last seen: 8 years, 3 months
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Re: "Seeing" without actually seeing... [Re: trendal]
#5933963 - 08/05/06 09:00 AM (17 years, 5 months ago) |
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This Book goes into great detail on the subject. Very interesting read.
-------------------- "Outside of a dog a book is a man's friend. Inside of a dog it's too dark to read" -Groucho Marx
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MushmanTheManic
Stranger

Registered: 04/21/05
Posts: 4,587
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Re: "Seeing" without actually seeing... [Re: trendal]
#5935537 - 08/05/06 09:54 PM (17 years, 5 months ago) |
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I think visual agnosia (the phenomenon you described) is excellent empiric proof of the unconscious.
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