blind man seeing

[General_Thral]

a while ago (about a year ) i saw a prgram about the power of the subconsous mind and one of the theories is tht blind people are still able to see subconsiously . the guys tested this out by getting a blind mans to put his face infront of a screen where lines would go across the screen and he had to guess what direction they were going in , and suprisiling he was able to guess no less than about 90% of them right , the guy said it was to do with the untap power of the subconsoius mind , i havnt been able to find the right test but i have found one similar http://digg.com/general_sciences/Bra..._just_the_eyes

[Ummon]

The phenomenon you refer to is blindsight, and it doesn't affect but those people who have lost their sight because of V1 cortical damage. In synthesis, these people have some residual abilities related to their reserve collicular circuit (a circuit which doesn't get involved in conscious vision), yet these do not amount to "seeing". In any case that phenomenon is an example of what is called the cognitive unconscious.

Notice that if these people's blindness was due to eye damage, no blindsight would occur.

[rathelios]

The vox of Ummon clamans no word of a lie. This is a very interesting and enlightening phenomenon. Various parts of the brain work together to create what we call vision. People with brain damage in different areas can present a whole host of symptoms: an inability to see moving objects, being able to perceive colour and nothing else, all kinds of weird and wonderful things.
This shows that what we see is a representation of reality, not actual reality.

[chris_uk_83]

I don't know about this blindsight, but I did see a program in which a blind boy had learned to echo-locate, using clicks. That was pretty awesome.

[LSJ]

There's a blind boy in my school who does that... funny actually.

[Ummon]

His parietal cortex being essentially intact, this is obviously possible: he learns to use the delay in the signal (as calculated by his olives (nuclei which are specialized in calculating binaural delays) and the properties of his ears (the diameters are arranged in such a progressively increasing way that stimulus height determines different reception times) to obtain a spatial map of the surrounding space.

Parietal cortex is also the end-circuit of blindsight, though in the case of blindight information is merely based on priming coming from an unconscious circuit.