Blind people see blackness?

jbomb27

It depends, I had an eye opening experience last year when I discovered that I was legally blind in my left eye, my right eye had been doing all the work. Being blind in one eye due to partial retina detachment I can still see a little bit out of that eye when I focus on try to use it the image is blurry like it would be if you were looking through like three feet of clear moving water, colourful but rough and no depth perception, in the dark only light stuff is 'visible'(blurred) out of that eye; everything else is black.

Coin

Borges, the Argentinian writer, went blind late in life, and made much of that when he did go blind, the color yellow stayed long after all other vision had gone. He described it like as the blindness set in, it was at first like everything was gradually over months disappearing into a yellow pea-soup fog. Eventually all sight went, and all he could see was an undifferentiated field of yellow.

BrutalMind

This is just kind of a "senseless" joke and sorry if anyone takes offense to it, but if you really want to know what blind people see, just poke your eyes out and you will "see". I know, it's an immature and uncalled for comment. But seriously, can we get a response from someone who was born with vision and later became blind? I realize that they would need help to post such a comment, but this may better help us understand what it is really like as opposed to assumptions based on what we consider to be rational explanations. I don't believe that people born blind and gained vision later would be able to describe it as well as vice versa. My ignorant mind assumes that what us sighted people "see" as darkness would be equivalent to what blind people do not "see". I realize that people born blind will not even know that the sense of sight exists, except for what they are told, so they will not be able to compare anything, but I feel confident that a person that becomes blind later in life will compare it to the visual representation of blackness or darkness, not blue or green or red but black (nothing).

whirled-peas

I read that when blind people take hallucinogens they can see the multi-colored show just like everyone else.

I imagine it doesn't work for people who have been blind from birth, since those neurons had to die from lack of stimulation.

I'd be interested to know if people who've gone blind find that their dreams slowly lose any visual content.

*Radrook*

What's the difference between not seeing anything because of blindness and not seeing anything because of being in a totally dark room?

BrutalMind

Quote by Radrook

What's the difference between not seeing anything because of blindness and not seeing anything because of being in a totally dark room?

The difference is that they do not experience or process visual data consistently. A person with sight will assign a visual object with properties such as shape, color, and dimensions, and these properties are determined by a light source shining upon the object. With no light source, the brain will determine a color or pigment based on the information provided to it, which we as humans acknowledge as black or dark, as we were taught in school. For a person that was blind from birth, I can't promise you that what they "see" is black or dark, because they don't actually see or perceive anything. That sense does not exist to them so there is nothing to "compare" it to. As for a person that became blind after birth, then I'm quite sure that they may find that the sensation of blindness is much what we sighted people conceive as dark or black, however, I've read in this thread that a man that became blind explained that if he could compare what he currently experiences, as visual perceptions, to colors, then he would compare it to a yellowish haze (kind of like facing towards a bright light with your eyelids closed), quite the opposite of what we would expect. Ultimately, what a sighted person sees in the dark cannot be directly applied/compared to what a blind person does not see because they are not the same thing thus not perceived in the same fashion.

sanko

It depends upon what kind of blindness he have .If its corneal things are just obscure he can feel strong light but as light deemers he feel more darker ,and total black in deem light .For retinal they sees black but they many times sees flashes,patterns of colours

*WhoWee*

A person I know that lost sight in one eye (accident). She see's nothing - like trying to see with her ear.

rhody

If I may, Vision science: Seeing without seeing

See thumbnail attached for: iPRGC diagram.

Russell Foster remembers his first human subject, an 87-year-old woman, as she sat in a dark room facing a backlit pane of frosted glass. A genetic disorder had destroyed the light-sensing rod and cone cells in her eyes, leaving her blind for the past 50 years. She was convinced that she would see nothing. But as the wavelength of light in the room shifted to blue, she reported — after some hesitation — a sort of brightness.

"That just blew us away," says Foster, a neuroscientist at the University of Oxford, UK, and one of the senior authors of a 2007 study reporting the finding1.

Foster and his collaborators had done nothing to treat the woman's blindness. Instead, her awareness of light owed itself to a class of light-sensitive cells discovered in 2002. Studies of these intrinsically photosensitive retinal ganglion cells (ipRGCs) have since revealed many surprises. Scientists initially thought that, rather than contribute to vision, the cells simply synchronized the circadian clock, which sets the body's 24-hour patterns of metabolism and behaviour, with changing light levels. However, recent work suggests that ipRGCs have been underestimated. They may also have a role in vision — distinguishing patterns or tracking overall brightness levels — and they seem to enable ambient light to influence cognitive processes such as learning and memory.

and

It became clear that under low light conditions, rods can set the body's clock, but some groups have suggested that under different conditions cones can as well. Perhaps more surprisingly, researchers have found that ipRGCs may contribute to visual perception. Hattar and others fluorescently labelled ipRGCs in mice to trace the projections of these cells to the brain. They found that ipRGCs reach into more brain regions than expected, including centres involved in visual processing: the dorsal lateral geniculate nucleus (LGN) and the superior colliculus. Mice without functioning rods and cones, but with intact ipRGCs, could even discriminate patterns in a visual test

and finally, which I was surprised, but not shocked to learn...

Steven Lockley, a neuroscientist at Brigham and Women's Hospital in Boston, Massachusetts, and his colleagues tested the reaction times of 16 healthy volunteers while they were exposed to either blue or green light for 6.5 hours. Those exposed to blue light had faster reaction times and fewer attention lapses when they were asked to report when they heard a sound10.

Lockley says that these different strands of research might eventually help to engineer 'healthier' light — using specific wavelengths, intensities or even patterns to activate brain pathways and improve mood, sleep or mental performance. "This research opens up a whole new field in terms of light applications, both for use therapeutically and for the general population," says Lockley.

I couldn't resist this. If you read carefully, science has been advanced by the persistent efforts of a few brave individuals who were dismissed and outright ridiculed when this discovery was presented. The other subject I researched and reported on similar to this was brain plasticity, here , something to think about...

Rhody...

edit: 3/4

P.S. How old does a thread have to be before being considered a necro-post ? Is it age and large number of responses similar to this one ?

Isaacsname

I haven't read a great deal about this, although it seems like a good question.

I did some volunteer work last year for a blind man , and I asked this very question. His response was that he saw black. I asked if rubbing his eyes gave any effect like it does to somebody with normally functioning vision, his answer was no.

Seeing as how there are what seems like more than a few different ways for somebody to lose their sight ( ie: parasites, cataracts, etc, ), there are probably a near equal amount of different states of functionality for those that do lose the ability to see normally, some see yellow ( mentioned above ) tunnel vision, cloudy vision, etc.

Someone could have physiologically intact eyeballs, suffer a brain injury and lose their sight that way, or even damage just to the optical nerve behind the eye. The mechanism would be different, as would a possible solution of restoring sight.

Interesting topic, that's my .02

Markface

Depending on the severity and degree of blindness. Majority of blindness isn't disfigurment to the eye itself, rather the processing and path of neurons moving to the ocipital lobe in the brain.

Disfigured paths can result in inverted imagery, inability to view moving objects, etc. Completely severed paths or damage to the ocipital lobe results in blindness, in which nothing is seen.

SHISHKABOB

maybe it works like this: cover one of your eyes with your hand, what do you see? The vision through the covered eye is sort of removed, and all you have left is the remaining eye's vision. Maybe what blind people see is like what I see through the covered eye.

nucl34rgg

I don't think they "see" black. They don't see at all. There is no visual sensation.

madness

http://en.wikipedia.org/wiki/Blindsight
http://en.wikipedia.org/wiki/Akinetopsia
http://en.wikipedia.org/wiki/Prosopagnosia

I think these kind of disorders demonstrate how specific aspects of our visual awareness can simply disappear with damage to the correct brain areas. A person who doesnt have the right brain area is simply missing that part of their awareness, and for congenitally blind people whose visual cortex never developed, I believe they are missing all sensation of vision. This is the same as a sighted person asking what they see behind their head.

sWozzAres

As I understand it, blackness is not due to the absense of light - rather it more like a background signal that your retina sends to the brain to signify that there is nothing there. Without it you could see hallucinations, or think you were dreaming, you would be very confused so this background signal blocks out internal imagery to stop you going crazy!

There is an interesting discussion on the subject in Three Laws of Qualia (P.440) where they talk about Charles Bonnet syndrome.

Patients with this disorder typically have damage to the retina, to the optic nerve, optic radiations, or sometimes even to area 17, producing blindness in either a large portion or in the entire visual field. But remarkably, instead of seeing nothing, they experience vivid visual hallucinations.

These patients had a sharply circumscribed region in the visual field where they were completely blind; i.e., they had a blind spot, or scotoma. The remarkable thing is that their hallucinations are confined entirely to the blind region.

One possibility is that the normal person, unlike the Charles Bonnet patient, has real visual input coming in from the retina and optic nerve. This is true, by the way, even when the eyes are closed, because there is always spontaneous activity in the retina, which may function to provide a null signal informing the higher centers that there is no rose here, and this prevents her from literally hallucinating the rose. (Indeed, this may be one reason why spontaneous activity in the peripheral receptors and nerves evolved in the first place.) Again, all this is very fortunate, otherwise your mind would be constantly flooded with internally generated hallucinations, and if you begin confusing internal images with reality, you will be quickly led astray.

Then there is the issue of synesthesia. The idea being that newborns experience synesthesia (mixing of the senses) and it's only through experience that they learn to differentiate sense information into vision/hearing/touch etc

Maybe a blind person who has experience of vision might hallucinate (periodically). A blind person with no experience of vision might have the visual areas in the brain taken over by other senses, so they have no ability to perceive any visual qualia.

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Coin	Borges, the Argentinian writer, went blind late in life, and made much of that when he did go blind, the color yellow stayed long after all other vision had gone. He described it like as the blindness set in, it was at first like everything was gradually over months disappearing into a yellow pea-soup fog. Eventually all sight went, and all he could see was an undifferentiated field of yellow.

whirled-peas	I read that when blind people take hallucinogens they can see the multi-colored show just like everyone else. I imagine it doesn't work for people who have been blind from birth, since those neurons had to die from lack of stimulation. I'd be interested to know if people who've gone blind find that their dreams slowly lose any visual content.

Radrook	What's the difference between not seeing anything because of blindness and not seeing anything because of being in a totally dark room?

sanko	It depends upon what kind of blindness he have .If its corneal things are just obscure he can feel strong light but as light deemers he feel more darker ,and total black in deem light .For retinal they sees black but they many times sees flashes,patterns of colours

WhoWee	A person I know that lost sight in one eye (accident). She see's nothing - like trying to see with her ear.

Markface	Depending on the severity and degree of blindness. Majority of blindness isn't disfigurment to the eye itself, rather the processing and path of neurons moving to the ocipital lobe in the brain. Disfigured paths can result in inverted imagery, inability to view moving objects, etc. Completely severed paths or damage to the ocipital lobe results in blindness, in which nothing is seen.

SHISHKABOB	maybe it works like this: cover one of your eyes with your hand, what do you see? The vision through the covered eye is sort of removed, and all you have left is the remaining eye's vision. Maybe what blind people see is like what I see through the covered eye.

nucl34rgg	I don't think they "see" black. They don't see at all. There is no visual sensation.