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Blind Man Navigates Obstacle Maze Unaided

samzenpus posted more than 5 years ago | from the matthew-murdock dept.

Science 191

iammani writes "The NYTimes runs a story about a blind man (blind because of a damaged visual cortex) successfully navigating an obstacle maze, unaided. Scientists have shown for the first time that it is possible for people who are blinded because of damage to the visual (striate) cortex can navigate by 'blindsight,' through which they can detect things in their vicinity without being aware of seeing them."

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191 comments

Huh. (0, Offtopic)

ScrewMaster (602015) | more than 5 years ago | (#26228387)

it is possible for people who are blinded because of damage to the visual (striate) cortex can navigate by "blindsight", through which they can detect things in their vicinity without being aware of seeing them."

Yeah okay ... that's kind of creepy.

Re:Huh. (-1, Troll)

Anonymous Coward | more than 5 years ago | (#26228393)

We assume that your blind nigger is well trained and very gentle. By gentle we mean that he won't bite, kick, or strike inappropriately.

We are going to cover four reliable ways of bringing your blind nigger to orgasm:

1) Masturbation. If he is fully withdrawn you may get him to drop his member by using one finger to lightly trace the opening cleft at the tip of his prepuce.
2) Blowing Him up. While grasping the shaft with one hand use the free hand to cup and massage the base of his member in the area of the scrotum. As he becomes more excited the erectile tissue associated with the glans-penis will engorge.
3) Intercourse - front to back. To do this safely requires the right nigger-to-person size relationship. If he is too long and your legs are too short you may be in trouble. I often have to stand on my toes while he goes at it to keep him from going too deep.
4) Intercourse - face to face. It has never happened to me but there is a good chance of getting an ashy mitt to the face with this, so wear head gear at least until the two of you have some facility with this. Also you will need to wear steel-toed boots. And you will need a few watermelons wrapped in blankets, or something similar in size and shape to that. A raw cantaloupe just won't do - he wouldn't like it, trust me.

All of this is generally difficult to do without watermelons unless your nigger has something to climb onto, and ideally this should be you. Lead your blind nigger to the place (cage, pen, stall, etc.) that you have selected to be your regular playspace. Remove his loin cloth and give him a couple of minutes to acclimate to the setting, piss, take a dump, whatever. He may or may not let down his member in either case.

Re:Huh. (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26228455)

wat

his eyes are fine (4, Informative)

timmarhy (659436) | more than 5 years ago | (#26228397)

his brain is still able to make use of the input comming from the eyes which are undamaged. interesting.

Re:his eyes are fine (0)

morgan_greywolf (835522) | more than 5 years ago | (#26228425)

No, he's not. Without a working visual cortex, nothing from the eyes enters the brain. At all. Most likely, he is using sound or air pressure. Blind people can often maneuver by hearing things like subtle changes in sound of footprints, etc., echoing off of or being aborbed by walls, etc. There are also subtle changes in air pressure as you approach obstacles, and that can often be 'felt' by blind people. The blind usually develop their other senses to a greater extent than sighted people as a means of compensating for the fact that they can't see. It just happens naturally.

Its not that hard (4, Interesting)

Iamthecheese (1264298) | more than 5 years ago | (#26228449)

After some practice I could do it myself. So can you. Start with a hallway with hard walls and walk down it blindfolded using your ears. It may help if you make a high-pitched sound. (at least high-pitched sounds are easier for me) I can only avoid large objects that don't aborb sound myself, but I bet I could get better.

Re:Its not that hard (3, Insightful)

morgan_greywolf (835522) | more than 5 years ago | (#26228459)

I don't doubt it all. Lots of people can. The brain automatically enlists your other senses when one of them isn't working. That's why I think the article is a just a load of BS. I don't think the man saw anything. I think his brain was just able to use his other senses to accomplish the same goal.

Re:Its not that hard (5, Insightful)

memristance (1285036) | more than 5 years ago | (#26228575)

There's only one way to be certain: repeat the experiment.

I would suggest having the blind man and an average-sighted man separately walk down a very well-lit corridor with randomly positioned (i.e., changing every iteration) obstactles 10 times, recording the amount of time each takes and the number of collisions. Reduce the amount of lighting by some increment and repeat the experiment. Continue reducing lighting until total darkness is achieved.

If the blind man is truly navigating by blindsight, both his course times and collision rates should roughly scale positively with those of the sighted man and inversely to the light levels. But then, that would be using the scientific method like the international team of neuroscientists in TFA (whom you are accusing of incompetence) did, so of course you wouldn't believe it...

Re:Its not that hard (3, Interesting)

BikeHelmet (1437881) | more than 5 years ago | (#26228751)

Brain Plasticity - his subconscious is figuring out how to make use of some form of input, to give him a sense that something is there.

I bet if he did it over and over, he'd get better at it. It'd strengthen the connections.

Re:Its not that hard (-1, Troll)

arotenbe (1203922) | more than 5 years ago | (#26228819)

Brain Plasticity - his subconscious is figuring out how to make use of some form of input, to give him a sense that something is there.

Alright, then. How about you suggest an experiment that would isolate the correct variable.

Stop coming up with excuses. If you can't suggest a better experiment, don't complain.

Re:Its not that hard (1)

BikeHelmet (1437881) | more than 5 years ago | (#26228973)

Brain Plasticity - his subconscious is figuring out how to make use of some form of input, to give him a sense that something is there.

Alright, then. How about you suggest an experiment that would isolate the correct variable.

Stop coming up with excuses. If you can't suggest a better experiment, don't complain.

No thanks. Someone would just prove it wrong in 5 years, anyway. :P

I wasn't complaining. Seems that all these theories have common roots.

Re:Its not that hard (5, Insightful)

Laser Dan (707106) | more than 5 years ago | (#26229169)

Isn't it obvious or am I missing something here??
Blindfold the blind man and repeat the experiment with/without the blindfold. That will tell if vision is being used in any way.

Re:Its not that hard (5, Interesting)

BradMajors (995624) | more than 5 years ago | (#26228467)

There is a video of a blind person on youtube who seems to be able to navigate just like a regular person through the use of echoes. He carries and uses a clicker to make sounds.

There is a group which teaches the blind to locate objects through echoes.

Re:Its not that hard (5, Funny)

weicco (645927) | more than 5 years ago | (#26229139)

There is a group which teaches the blind to locate objects through echoes.

Bene Gesserit?

Sorry, I'm reading the book Paul of Dune which I just got as a Christmas present. Couldn't help myself... :)

Re:Its not that hard (5, Informative)

GarrettK18 (1200827) | more than 5 years ago | (#26228761)

Full disclosure: I was born 3.5 months premature, and my retinas detached at 4 months.

I call it being able to hear the "sound shadows" of objects, because that's really what they are - an object blocks sound, and that blockage is projected to the ear. With a good cane, I can navigate around tables, columns, and even position myself relative to peoples' voices to keep myself from running into them. It's quite amazing what you can tell with a good hallway, and a constant sound source (soda/vending machines are good). For example, an open, echoy space usually means a stairwell.

Also, randomness ... the first time I went to post, my screen reader [gnome.org] was very sluggish and crashed. I guess Slashdot hates blind Linux users.

Re:Its not that hard (1)

TheModelEskimo (968202) | more than 5 years ago | (#26228809)

Don't worry, Slashdot is the tab that always crashes Firefox for me now, and I'm not blind. I think Slashdot just hates everybody. Before us I guess it was IE users. ;-)

Re:Its not that hard (4, Interesting)

lgw (121541) | more than 5 years ago | (#26228881)

That's very cool. It's also proof of how amazing the brain is - the part that makes a 3D model of your surroundings will adapt to any sort of useful input. With just sonic shadows you're working with very limited data, but even so: the navy has spent a ton trying to develop good passive sonar, and it sounds like you're better at it than the technology. Now if someone could just invent a sonic lens, it would close the gap. The only reason light gives better 3D positional information is the lens (though it would also be helpful to hear sub-millimeter wavelengths, as 20 kHz doesn't give much precision).

Re:Its not that hard (1)

Laser Dan (707106) | more than 5 years ago | (#26229177)

Would a blind person be an awesome sonar operator then?
Just plug 'em into the array with no processing of the signal...

Re:Its not that hard (0)

Anonymous Coward | more than 5 years ago | (#26229315)

Now if someone could just invent a sonic lens,

Yeah, if only [wikipedia.org] ...

Re:his eyes are fine (1)

timmarhy (659436) | more than 5 years ago | (#26228453)

RTFA and you'll see your wrong (too much to ask?). it's a form of vision he is using.

Re:his eyes are fine (0, Redundant)

morgan_greywolf (835522) | more than 5 years ago | (#26228469)

I did RTFA. And I think the article is a load of BS. The visual areas of the brain will light up because the brain doesn't know the difference between what you see with your eyes and what you see with your imagination and memories. IMHO, sight doesn't happen as much in the eyes as it does in the brain.

Re:his eyes are fine (5, Informative)

Anonymous Coward | more than 5 years ago | (#26228627)

Maybe the problem is that TFA tried to make the science more approachable to people, but you obviously don't understand a single thing about blindsight. This is nothing new at all. In layman's terms, the participant still experiences visual sensation but not visual perception -- they can still see, but they are unaware of it. What is significant in this case is the extent of the damage to the visual cortex. The sensory compensation of congenitally blind people is incredible, but this is an entirely different phenomenon.

Sight doesn't "occur" in the eyes, but there are a number of subcortical structures the information passes through before it gets to the visual cortex. Which, oddly enough, is exactly what they say in TFA, which you claim to have read. They specifically say that the "visual areas of the brain" did NOT "light up", so I have no clue what you're babbling about.

The entire point of the article is that the extent of subcortical visual processing (which we are unconscious of) is greater than most people realise. So feel free to read it again and appreciate what is actually a well-established neurological phenomenon.

Re:his eyes are fine (4, Informative)

sveard (1076275) | more than 5 years ago | (#26228799)

http://www.amazon.com/Physiology-Behavior-MyPsychKit-Neil-Carlson/dp/0205593895/ref=pd_bbs_sr_1?ie=UTF8&s=books&qid=1230187013&sr=8-1 [amazon.com]
Chapter 1 has a short item on blindsight and it's relation to consciousness. You should really read chapter 1 of this book.

IMHO, sight doesn't happen as much in the eyes as it does in the brain.

Well, that's how the brain does its thing. Your eyes, ears, nose, skin, are instruments that extend from the brain. Data that flows from your senses to your brain lacks meaning until the brain processes it.

A few posts earlier you say:
( http://science.slashdot.org/comments.pl?sid=1072951&cid=26228425 [slashdot.org] )

Without a working visual cortex, nothing from the eyes enters the brain. At all.

Blindsight does not imply that the visual cortex does not "work". Have a look at http://en.wikipedia.org/wiki/Primary_visual_cortex [wikipedia.org]

Data still flows from the eyes over the optical chiasm to the primary visual cortex (the cortex around the calcarine fissure in the occipital lobe). From there, there are multiple "streams" of visual data. One of those streams is the one that "enters" consciousness.

It is the absolute certainty with which you refute the previous, and the postulation of the following near-superhuman senses that make you appear rather uninformed and quite arrogant.

Most likely, he is using sound or air pressure. Blind people can often maneuver by hearing things like subtle changes in sound of footprints, etc., echoing off of or being aborbed by walls, etc. There are also subtle changes in air pressure as you approach obstacles, and that can often be 'felt' by blind people.

Take a biological psychology course or your own medicine (your signature)

http://www.scholarpedia.org/article/Blindsight [scholarpedia.org]
http://en.wikipedia.org/wiki/Blindsight [wikipedia.org]

Comedic irony (1, Funny)

Anonymous Coward | more than 5 years ago | (#26228705)

RTFA and you'll see your wrong

Re:his eyes are fine (0)

Anonymous Coward | more than 5 years ago | (#26228473)

You need to RTFA. Not all sensory data collected by the eye is processed by the visual cortex.

Re:his eyes are fine (5, Insightful)

philspear (1142299) | more than 5 years ago | (#26228489)

Without a working visual cortex, nothing from the eyes enters the brain. At all.

It would be really nice if hypothesis and biology worked like that, where biology followed our hypotheses, but it doesn't. It would be interesting to see an fMRI, or see if he could navigate the maze with earplugs or some way of throwing off air pressure. Assuming it can't possibly be his eyes connecting to some other part of the brain simply because textbooks say the eyes connect only to the visual cortex is not a safe conclusion.

Re:his eyes are fine (1)

ceoyoyo (59147) | more than 5 years ago | (#26228519)

Read the article. Carefully. There's good evidence from other mammals that subcortical structures are activated in response to particular visual stimuli, independently of the cortex.

Re:his eyes are fine (4, Informative)

Tekoneiric (590239) | more than 5 years ago | (#26229145)

Most likely those subcortical connections are there as a link to the reflex system. High level visual processing would likely take too much time to process for reflex action. Damage to the subcortical links but not to the visual cortex would likely make for someone that's slower to react to visual stimulus and very clumsy.

Re:his eyes are fine (5, Informative)

ceoyoyo (59147) | more than 5 years ago | (#26228505)

"Without a working visual cortex, nothing from the eyes enters the brain. At all."

Whoopsie. Apparently you didn't know about the body of work showing that there are connections between the retina and subcortical areas as well as the striate cortex. Of course, if you'd read the article, you would have noticed they mentioned that.

Yes, I read your other comments, including the one where you claim to have read the article. To summarize: you don't think it's possible... because .

Re:his eyes are fine (3, Informative)

iocat (572367) | more than 5 years ago | (#26229273)

Actually, if you look at the video found here [blogspot.com] , you'll see that your theory of human echo-location is totally inadaquate to describe what he is doing -- he avoids the walls, but also an overhead projector on the floor and some really small items.

If you RTFA (I know, a big assumption -- Google can take you to the no-registration-required SciAm version), they say that scientists suspect there are other pathways where the info is getting into his brain, even though his visual cortex is totally destroyed on both hemispheres. This is the first blindsight demo with NO visual cortex, and thus seems to suggest strong that there are some alternate pathways going on. He can also react to facial expressions.

Re:his eyes are fine (2, Informative)

MillionthMonkey (240664) | more than 5 years ago | (#26229313)

"No, he's not. Without a working visual cortex, nothing from the eyes enters the brain. At all. Most likely, he is using sound or air pressure."

The signal from the optic nerve doesn't go exclusively to the primary area of the visual cortex- it forks at the lateral geniculate nucleus before it gets there and some also goes to subcortical targets which provide functions like the flinching reflex. These are older pathways and modern vision evolved by eavesdropping on the signal.

Ben Underwood (0, Redundant)

futuresheep (531366) | more than 5 years ago | (#26228401)

Navigating by sound.

http://www.benunderwood.com/ [benunderwood.com]

http://www.cbsnews.com/stories/2006/09/06/eveningnews/main1977730.shtml [cbsnews.com]

Ben had cancer in both eyes. But he discovered a way to beat his blindness. When he was about 6, he started "clicking," and quickly realized that the sound he made with his tongue bounced off things around him, giving him an idea what was there.

Re:Ben Underwood (4, Informative)

Gabrill (556503) | more than 5 years ago | (#26228423)

TFA specifically states that they ruled out echolocation.

Since you apparently read TFA (1)

NotQuiteReal (608241) | more than 5 years ago | (#26228617)

Did they also rule out long whiskers? Or perhaps other unsightly hair. A blind person might not have the best grooming habits.

(Am I going to hell for posting this on Christmas eve?)

Re:Since you apparently read TFA (1)

multisync (218450) | more than 5 years ago | (#26228925)

Maybe he's got really long, Howard Hughes-like toe nails that he's subconsciously using to detect the boxes and tripods.

(Happy Christmas!)

Re:Ben Underwood (1)

quantaman (517394) | more than 5 years ago | (#26228661)

TFA specifically states that they ruled out echolocation.

Well they said they found no evidence that he was, I'd still like if they elaborated that they gave him earplugs or something, even footsteps could give him enough audible info to navigate.

Ideally I'd like some mention of a control using a blindfold or something. From the sounds of it he wasn't truly blind, the eyes worked fine but signals either weren't getting to the brain, or weren't getting processed by the visual cortex. They seem to be suggesting the visual info is still somehow being processed to aid navigation.

Re:Ben Underwood (1, Informative)

Anonymous Coward | more than 5 years ago | (#26228733)

From the sounds of it he wasn't truly blind, the eyes worked fine but signals either weren't getting to the brain, or weren't getting processed by the visual cortex. They seem to be suggesting the visual info is still somehow being processed to aid navigation.

.

Congratulations, you found the point of the article. Many have failed to do so.

How old are you? (1, Insightful)

Anonymous Coward | more than 5 years ago | (#26228805)

Take away a 50+ yo man's sight, and in most cases he won't be compensating all that well with hearing. It's partly accuity -- us old farts don't hear all those nice directional high frequencies as well as we used to; and it's partly about what it takes to learn a skill.

Best to start early, because it will take years of practice to do it well and it may well be that your adult mind, after 50 years of primarily visual processing of spatial information, will have a hard time using auditory inputs for that purpose.

Re:Ben Underwood (1)

GarrettK18 (1200827) | more than 5 years ago | (#26228811)

Ben Underwood , while a very inventive individual and cause for many "feel-good" stories in the media is, imo, a pussy. I'm going to laugh my ass off when he goes to an unfamiliar town (with no cane, mind you) and gets very disoriented. I spent almost a year with these guys [lbc-ruston.com] , and they taught me a thing or two about echo-location and traveling.

Failed attempts (0)

Anonymous Coward | more than 5 years ago | (#26228415)

If this is the first time they've successfully shown it...Think about how all the times they tried and failed.

Dolcet berries... (0)

Anonymous Coward | more than 5 years ago | (#26228479)

Wil McCarthy's "Queendom of Sol" science fiction series released a few years back had Blindsight used as the basis of an advanced martial arts discipline in the final volume, "To Crush The Moon" [wilmccarthy.com] . (Read them in order or you'll be very confused). He swore he wasn't just making the phenomenon up at the time. So... guess he wasn't.

Blind awareness? (1, Interesting)

IrritableBeing (1281212) | more than 5 years ago | (#26228507)

So how can someone be aware of something in the vicinity without seeing or touching it? Are they saying that this guy has developed some type of sixth sense? Or is this an ability that everyone has.. like when you're sleeping and someone gets real close to you, you wake up as if your subconscious detected them.

If this is true, then we should try to tap into this ability more often. You know, train ourselves to be able to use it on command or 24/7. I can think of a few instances where this could come in handy.

Re:Blind awareness? (0)

Anonymous Coward | more than 5 years ago | (#26228699)

If you had RTFSummary, you'd know that there is nothing wrong with his eyes, his blindness is entirely due to brain damage and that his ability to navigate was not due to other senses, but information from the eye being received in subcortical areas and relayed without conscious knowledge.

Sighted Persons Unable to Navigate TFA (5, Funny)

Oswald (235719) | more than 5 years ago | (#26228509)

Doctors remain baffled at the inability the majority of Slashtards to read and comprehend a simple article summarizing a medical experiment, despite apparently functioning visual systems. "They just wouldn't quit insisting that the subject of the experiment used echolocation to navigate the obstacles in the hallway, no matter how clearly and explicitly the article explained that the possibility had been ruled out," say baffled researchers. "We don't think their brains are wired correctly."

Re:Sighted Persons Unable to Navigate TFA (4, Funny)

sagematt (1251956) | more than 5 years ago | (#26228587)

I didn't bother to read the whole FA because I am blind, you insensitive clod!

Re:Sighted Persons Unable to Navigate TFA (0)

Anonymous Coward | more than 5 years ago | (#26228601)

Slashdotters have long been known for their ability to navigate replies on a topic without seeing TFA.

Re:Sighted Persons Unable to Navigate TFA (1)

jesdynf (42915) | more than 5 years ago | (#26228999)

Alright, you. I use this phrase vary sparingly -- but, I did indeed Laugh Out Loud. So there you go.

It's Ch'i energy (-1, Offtopic)

lena_10326 (1100441) | more than 5 years ago | (#26228511)

We sense it. We transmit it. Assuming we've solved all the mysteries of the body is naive. http://en.wikipedia.org/wiki/Ch'i [wikipedia.org]

Re:It's Ch'i energy (-1)

steelfood (895457) | more than 5 years ago | (#26228637)

I haven't read TFA because the genius who submitted it used a registration-required link. But I'm guessing it's more of a mix between vibration perception and echo location.

When somebody or something moves, it create vibrations, in the air, and on the ground. On certain types of flooring, I can sense when somebody is approaching me with my eyes closed, because I can feel the tiny vibrations that their step creates. If the movement is fast, I can feel the air displacement. It's not accurate, but it's enough that I usually turn towards where the movement is.

And, barring that, there's always the ability for one to create their own vibrations and hence echoes. You can create it by stomping (to determine where walls are), or by snapping. Again, it's not accurate, but it's probably enough.

As for the chi theory, I'm going to go ahead and say it's not chi. In fact, I'm not going to go into depth about what I think chi is, but I'm not sure this fits within the concept of chi at all.

Re:It's Ch'i energy (0)

Anonymous Coward | more than 5 years ago | (#26228669)

It's Ch'i energy

His qi energy...IT'S OVER 9000!

Re:It's Ch'i energy (1)

justinlee37 (993373) | more than 5 years ago | (#26228765)

We sense it. We transmit it. Assuming we've solved all the mysteries of the body is naive.

I think you are the one making "assumptions."

Re:It's Ch'i energy (-1, Flamebait)

bussdriver (620565) | more than 5 years ago | (#26228891)

Don't bother suggesting things modern science does not understand yet. This is slashdot, home of the rigid narrow minded science types who practice their brand of science like a religious zealot.

One has to experience it to believe anything is going on; its just too "out there" to believe otherwise... but many just dismiss it without testing it; won't even try to explore it. Its a common problem in science; as one can see some of the dismissed and harassed were later vindicated (no, that is not the norm but its far more common that theories are dismissed without serious investigation.)

I've tried a bunch of stuff; just for curiosity. Most was bunk; some was fun even though it was bunk-- like I went on a ghost hunt TV show (cameraman #1) and found it entertaining between long periods of NOTHING. No, there were NO GHOSTS the whole time; but watching them act up over nothing... that was an experience.

Past life regression. interesting stuff. nothing checks out and one is quite creative in that state. (well, 1 lady's story did check out perfectly which was odd...like lottery level odds.) Speaking of which, hypnosis itself had quite a few skeptics...

Re:It's Ch'i energy (0)

Anonymous Coward | more than 5 years ago | (#26229099)

Umm, it still does, on the level of sodium penethol: you condition yourself to drop your guard and you've effectively invited yourself to believe and create whatever you want. It will not change long-term behavior, but it will mess with your head when it tries to reconcile the conflicts in your memory.

BSD's final Christmas (-1, Offtopic)

Anonymous Coward | more than 5 years ago | (#26228513)

Fact: *BSD is dying.

"Spirit," said Scrooge, with an interest he had never felt before, "tell me if *BSD will live."

"I see a vacant seat," replied the Ghost, "in the poor chimney-corner, and a crutch without an owner, carefully preserved. If these shadows remain unaltered by the Future, *BSD will die."

"No, no," said Scrooge. "Oh, no, kind Spirit! say it will be spared."

"If these shadows remain unaltered by the Future, none other of my race," returned the Ghost, "will find him here. What then? If it be like to die, it had better do it, and decrease the surplus operating system population."

Scrooge hung his head to hear his own words quoted by the Spirit, and was overcome with penitence and grief. It was sad to see any operating system die, even one so obviously flawed and useless as *BSD.

God bless us, every one.

Re:BSD's final Christmas (0)

Anonymous Coward | more than 5 years ago | (#26228755)

That was actually kinda sweet.

Turn in your nerd badge (4, Interesting)

BitHive (578094) | more than 5 years ago | (#26228569)

Whoever tagged this "badscience" should take an introductory neuroscience course sometime.

For those whose curiosity hasn't entirely been replaced by fashionable knee-jerk skepticism, your optic nerve does not only terminate in what we think of as primary visual cortex, it sends projections to other areas as well, though these areas do not contribute to what most of us think of as "sight"

Re:Turn in your nerd badge (2, Insightful)

Kingrames (858416) | more than 5 years ago | (#26228917)

It should be no surprise that a blind man can navigate a maze. Blind men have successfully navigated mazes faster then others for quite a while.

That's because their navigational algorithm is much simpler. put your hand on the right wall and follow it.

You'd be surprised how much easier things can get when you eliminate useless data. This, however, seems to be a more noteworthy experiment in that it was more than just a regular old maze with two ends.

Perhaps this will be the first step in discovering psionic potential? If so, sign me up for multiclassing.

Uhno (4, Informative)

ShakaUVM (157947) | more than 5 years ago | (#26228611)

This is hardly the first time blindsight has been demonstrated. I recall Ramachandran at UCSD doing experiments on it a while back.

One of the more mind blowing things I read in 2008 was the discovery of a third type of visual receptor besides rods and cones. Essentially there's a third type of receptor that only detects sort of gross levels of light, and feeds directly into the system which regulates your circadian rhythm and is used for some other purposes. People that were completely blind were able to tell when light levels were fluctuated in a large way, like walking in front of a TV, and be totally puzzled how they knew that, since it didn't register as sight at all for them.

The fact that these neuroscientists would call it the first evidence for blindsight means that either they really didn't read their papers very well, or it was a bad article summary on Slashdot.

Re:Uhno (1)

Belial6 (794905) | more than 5 years ago | (#26228685)

Or maybe they just heard the incredibly load buzzing that TVs emit when they are turned on.

I jest about doubting you, but I'm serious about the TVs. Those things are loud!

Re:Uhno (1)

daniel_newby (1335811) | more than 5 years ago | (#26229423)

One of the more mind blowing things I read in 2008 was the discovery of a third type of visual receptor besides rods and cones. Essentially there's a third type of receptor that only detects sort of gross levels of light, and feeds directly into the system which regulates your circadian rhythm and is used for some other purposes.

Those are the photosensitive retinal ganglion cells [wikipedia.org] . In addition to driving the circadian rhythm generators, they also control pupil size in response to light. IIRC, research in cats found that they do connect to the visual cortex, although how the signals are perceived is not yet known.

My daughter confirmed this story for me a year ago (4, Interesting)

LenE (29922) | more than 5 years ago | (#26228645)

My daughter had a stroke before she was born, and as a result, she suffers from Cortical Visual Impairment (CVI), like the subject of this story. At nine months of age, she couldn't tell light from dark, which really screwed up our sleep cycles. Her eyes were fine, but her brain could not process the signals that they were sending to her.

Eventually, she did regain some amount of vision, but her hearing is still her primary way of "seeing" things. Whenever we go into places that are pitch dark, my wife and I are walking into things left and right. My daughter, on the other hand, cruises right around like a bat. She hears walls and other obstructions, and corrects her course to avoid them. Her object avoidance skills greatly diminish when she can use her eyes to see, as her brain has to work much harder to decode what she sees with her eyes.

-- Len

Blindsight, Deafhearing and Alien Limbs (4, Informative)

DynaSoar (714234) | more than 5 years ago | (#26228649)

There are two distinct causes of blindsight (and deafhearing and alien limb syndrome), damage to the primary sensory cortext but not the secondary or assosiation cortices, and damage to the association cortex, but not the sensory.

The latter is easy to explain. The person can perceive, but can't incorporate the fact of it into their conscious experience. They can't "own" the perception. This is very often found in damage to the somatosensory cortex which leaves partial paralysis. Often the person can't perceive the limb attached to their body as 'theirs'. Sensations in the limb do not become perceptions for them. Similarly, vison and hearing can occur, and the brain can make use of the data, but the person can't perceive it because it's not coming from "them".

The former is harder to explain. There seems to be a parallel visual (and auditory) system through which information can pass and the brain make use of, but which bypasses the association cortex. The person can't perceive normally, but if tested they react as if they can. They can, for instance, consistently "guess" the number of fingers shown them. There is a similar system for somatosensory. Perception of touch to, say, the hand, has highly detailed "maps" elsewhere on the body. For the hand it's on the cheek and on the back just below the shoulder. Just why this secondary pathway exists is a mystery. But it does, in most people.

Around 20 years ago in Coevolution Quarterly there was an article about a 'school' in (IIRC) New Mexico that taught people to use their blindsight to navigate in the desert at night. The secondary visual pathway that persons with the second form of blindsight use, exists intact in everybody. It's not something you develop because of damage, it's something that's there in case you need it but below the level of consciousness so as not to interfere with normal perception. Occasionaly hunters, hiker/campers or survival technique practioners will hear of a person who can literally run through a pitch black forest without running into anything. These people have the ability to react to the subliminal perception from the secondary visual system in what occurs to them as instinctive reactions because they don't consciously perceive anything.

Re:Blindsight, Deafhearing and Alien Limbs (4, Interesting)

Plekto (1018050) | more than 5 years ago | (#26228893)

There's also other differences as well. Some women, for instance, have see a fourth set of colors, which gives them a much greater low-light ability (a couple for every thousand women, IIRC) as well as do great things in the visual arts. Other people have vision that extends a bit beyond the normal ranges as well. A good example if this is the typical "normal" body temperature. It was obtained by sampling a large number of people and averaging the result. Vision, hearing, and other senses are similar. So it's not surprising that the occasional blind person can actually tap into these if theirs happen to naturally be more developed than normal.

By tapping into the secondary pathways like this, I can "see" about twice as well as most people in the dark(though it's not really "seeing" like reading a paper or like a cat does). And, as DynaSoar mentioned, I can literally run through areas at night and not hit things as long as there is even a tiny amount of light.(doesn't work in caves/absolute pith black - tried that - heh)

Note - the skill can be learned, though some see better at night than others. I suspect their vision is shifted a bit more towards the infrared or their iris' are a bit larger. It took me about 2-3 years to develop it when I was growing up. My friends and I always spent a lot of time playing outside at night and some of us got pretty good at avoiding things in the dark. The hard part was learning to just trust your instincts. It's a odd feeling, though, as you only notice things a split second before you normally would hit them if you're moving faster than walking speed.

I found that a trick to doing this - and you can try this as well - is to learn to defocus your eyes during the day. Animals do this to track movement. It's a common trick hunters also use to track and find game. If you can then also do this at night, it basically shuts off a lot of your brain's trying to strain itself in low light. Since the average person's brain normally focuses intently upon just a small area in front of them, expanding that to your entire field of vision makes a huge difference.(though as noted, you can't focus on specific objects at the same time) Often, even if you can't actually see details, your eyes will notice things like faint reflections, movements, and so on.

My ex? She's nearly completely blind about 5 minutes after dusk. Opposite end of the scale as it were.

Re:Blindsight, Deafhearing and Alien Limbs (1)

DynaSoar (714234) | more than 5 years ago | (#26229271)

Plekto, are you reading my mind? I purposefully withheld mention of my own night vision. You supplied not only details of it, but of how I developed it. Your accounting tells the tale so exactly it's almost spooky. But given the mind that I have, it ends up as considering how much more likely I am to be able to find and test enough people in a similar task in order to determine why some have this and others do not.

One point of contention, there are not "some women that see in 4 colors". There are some people called tetrachromats who have four color receptors. They do not see four colors, they see the same appx. 3.5 million colors. They just have better color acuity (they can tell the difference between two colors better).

See It Now (4, Interesting)

hyades1 (1149581) | more than 5 years ago | (#26228721)

If you ever want to see this in action, there's a very simple experiment you can do. Put a quarter inside a ring of five loons (Canadian $1 coins). Put another quarter inside a ring of five dimes. The quarter surrounded by dimes will look larger than the other one.

Reach out and pick one up. Put it back. Pick the other one up. Put it back. You'll notice that even though your eye is telling you the two quarters of different sizes, your fingers will automatically spread out just the right amount to pick up either coin.

The illusion works for your regular visual system. The unconscious one gets the answer right.

By Neruos (0)

Anonymous Coward | more than 5 years ago | (#26228725)

Nothing new here. The blind people who have hearing, normally gain heighten hearing after awhile. This in turn, develops out to like sonar. You know how you feel someone sneaking up on you, although you don't hear or see them (but you have that sense that someone is there). That is echoing presense.

A blind person with no visual input or noise input, can not navigate unless they have a start, finish and repeation.

Re:By Neruos (1)

jcr (53032) | more than 5 years ago | (#26228899)

For as long as I can remember, I've been able to tell when I was near a wall in a dark room, or with my eyes closed. I don't know if I'd describe it as sonar per se, but I can also tell if someone is standing close to me, no matter what our relative positions are.

FWIW, the last time I tested it with a tone genererator, my hearing topped out somewhere around 25Khz. I'm sure it's far lower now, but I can still tell if there's a CRT monitor powered on anywhere within fifty feet of me or so.

-jcr

This works because... (2, Interesting)

Col Bat Guano (633857) | more than 5 years ago | (#26228727)

...the brain has a layered architecture. The more primitive brain has its own visual processing system. Evolution has built connections with this system and the parts of the brain that deal with awareness. Lose this connection and you can still "see", but not be aware of them (at a very high level).

well how about smileys (1)

vkoivula (1432063) | more than 5 years ago | (#26229049)

Soon we are going to have a story of a blind man that reacts to smileys even thought he can't read.

vision without "seeing" is possible (0)

Anonymous Coward | more than 5 years ago | (#26229201)

I used to suffer from severe migraine, migraine is NOT "just a headache", but a very unpleasant and disabling complaint that leaves you feeling very ill and disoriented with a severe intolerance to light, or, as in the case of my more serious attacks, I lost the use of my vision completely.

the weird thing was that I could still move about (cautiously) and knew where a lot of obstructions where (even mobile things like doors or other people) but I couldn`t see a thing, just some sort of crazy disjointed fractal kaleidoscope effect that had no discernible relationship between what was going on around me and the muddle that was what I was "seeing"

so my personal experience is that you CAN not see anything intelligible and still be able to detect things, it`s weird because you would think that seeing something was the act of knowing it was there, but at some level I think the brain treats "object" and "visual object" as different things, the information is probably split off before it gets to the visual cortex.

I don`t think it had anything to do with "sonar" either, I could tell a person I knew was walking towards me from inside a building in a busy environment, no chance I could so much as hear their footsteps from inside with other people moving about, so I could not have recognised anything distinctive about their steps for example

see it to believe it (1)

mrbobjoe (830606) | more than 5 years ago | (#26229301)

"You just had to see it to believe it" said Beatrice de Gelder

Oh now that's just cruel.

Bilaterality of blindsight is special (2, Interesting)

GeertNimage (1017394) | more than 5 years ago | (#26229397)

It is not mentioned very clearly in the NYT article, but it is mentioned in the original Current Biology paper: this patient has BILATERAL lesions in both the left and right visual cortices. IMO, this is what makes this case especially interesting.

Of course, blindsight has been demonstrated many times before, but always in patients with unilateral lesions. This has some methodological advantages (the patients can act as their own control), but the unilaterality has also been criticised. Maybe these patients make microsaccades, maybe some light is reflected by the nose into the other eye halves, etc. In short, maybe some information reached the intact hemisphere.

This is not possible in the present patient, and that is especially interesting. AFAIK, this is the first and only patient with a bilateral blindsight.

-- Geert

I bet ya 5 altarian dollars that ... (1)

nargileh (1113371) | more than 5 years ago | (#26229449)

the obstacle avoidance rate would increase if you hire people with surprising bodies or opinions to leap out from behind the obstacle and exhibit and/or explain them at the crucial moment.

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