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Science

Blind Man Navigates Obstacle Maze Unaided 191

Posted by samzenpus
from the matthew-murdock dept.
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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Blind Man Navigates Obstacle Maze Unaided

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  • his eyes are fine (Score:4, Informative)

    by timmarhy (659436) on Thursday December 25, 2008 @01:23AM (#26228397)
    his brain is still able to make use of the input comming from the eyes which are undamaged. interesting.
  • by memristance (1285036) on Thursday December 25, 2008 @01:25AM (#26228407)
    Blindsight is 20/20.
  • http://en.wikipedia.org/wiki/Zatoichi [wikipedia.org] My favorite Japanese movies. Gotta love Shintaro Katsu's portrayal of a blind man.
  • by Oswald (235719) on Thursday December 25, 2008 @01:48AM (#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."
  • by BitHive (578094) on Thursday December 25, 2008 @02:07AM (#26228569) Homepage
    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    For those whose curiosity hasn't entirely been replaced by fashionable knee-jerk skepticism, your optic nerve does not only terminate in what we think of as primary visual cortex, it sends projections to other areas as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: (Score:3, Insightful)

      by Kingrames (858416)
      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 discoverin
  • Uhno (Score:5, Informative)

    by ShakaUVM (157947) on Thursday December 25, 2008 @02:17AM (#26228611) Homepage Journal

    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.

    • by Belial6 (794905)
      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!
  • ...FTW.
  • by LenE (29922) on Thursday December 25, 2008 @02:26AM (#26228645) Homepage

    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

    • by mutende (13564)
      Look at this guy navigating by clicking his tongue: http://www.youtube.com/watch?v=NI9cGYWKs_8 [youtube.com].
      • by LenE (29922)

        My daughter, who is now four years old, is very attuned to large spaces that echo. She can hear them coming and as she approaches, she usually shouts "Ha!" to hear it come back to her.

        That being said, she doesn't need to click her tongue to sense walls and such. Even in quiet rooms, there is enough ambient noise from her motion and things around, that she can sense the location and more importantly the nearness of objects. When she "looks" at something, she is rarely looking straight at it. She lowers h

        • by Reziac (43301) *

          She may also be sensing air currents with the fine hairs on her face and neck.

          One of the ways you can readily spot a blind cat is that it will ALWAYS keep its whiskers stretched forward -- not to touch things with, but to sense micro-currents that surround objects, so as to avoid running into them. These cats can be good enough at it that their owners won't believe the cat is blind. I once had a very old cat who was both totally blind and stone-deaf, and he navigated entirely via this whisker-based "air sen

    • by Mal-2 (675116)

      I'm not surprised by the fact that her poorly processed vision can actually be a hindrance at times. Personally, if I try to walk through an unfamiliar dark room (whether it's really dark or my eyes just haven't adapted yet), I'll fumble around and walk haltingly. If I close my eyes, it's like my brain "gives up" on trying to use the eyes, and much of the weirdness goes away. I may still walk into things, but I'll do it with confidence.

      I think your daughter might be better off just closing her eyes when the

  • by DynaSoar (714234) on Thursday December 25, 2008 @02:26AM (#26228649) Journal

    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.

    • by Plekto (1018050) on Thursday December 25, 2008 @03:42AM (#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.

      • by DynaSoar (714234)

        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 peopl

        • by sjames (1099)

          The same visual technique can also be used to spot dim satellites. Start out fully de-focused looking over the entire sky. Before long, you'll feel an 'urge' to look to a particular place. DO NOT do so. Instead, look near that point but not quite focused. Then you can see the rather dim light moving slowly against the background. It may appear to blink out occasionally if you let it get too close to your central vision (it is a constant brightness, the blinking is a visual artifact).

          • by DynaSoar (714234)

            The same visual technique can also be used to spot dim satellites. Start out fully de-focused looking over the entire sky. Before long, you'll feel an 'urge' to look to a particular place. DO NOT do so. Instead, look near that point but not quite focused. Then you can see the rather dim light moving slowly against the background. It may appear to blink out occasionally if you let it get too close to your central vision (it is a constant brightness, the blinking is a visual artifact).

            It's also how those with very good or well corrected vision can see Mizar's visual double Alcor (the star in the center of the Big Dipper's handle). The separation is enough, but Alcor is much dimmer and difficult to perceive, especially with current levels of light pollution.

            It's not the same. I've been an amateur astronomer for over 4 decades and am very familiar with the technique. It's based on the fact that the more light sensitive rods are squeezed out of the central visual field by the color sensitiv

            • by sjames (1099)

              It's not the same. I've been an amateur astronomer for over 4 decades and am very familiar with the technique. It's based on the fact that the more light sensitive rods are squeezed out of the central visual field by the color sensitive cones, making things only a few degrees off center appear brighter. The off-center technique still results in conscious perception. Blindsight/night vision does not. OTOH, that makes night vision suck for astronomy; it does no good to look if you don't know you're seeing it.

              It isn't exactly the same, but the part of finding the satellite IS based on the alternative visual pathways. The rest is significant training of both conscious and unconscious pathways to prevent attempts to track to the center of vision.

              Beyond potential for rehab, the big reason neurophysiologists are interested in blindsight is that it affords the opportunity to map out which part of the visual systems does what for us. Very few people are even aware of it at all other than having visual perception. Sail

            • by Reziac (43301) *

              [blink] I'm a little nearsighted (20/40 and 20/80) but I can see that double star without even thinking about it. With correction, it's perfectly evident.

              However, I'm one of those freaks with obscenely precise colour vision; I also see VERY well in the dark (and tend to see better by looking straight at something than by the "not quite at it" technique). I suspect the two abilities are related. -- Conversely my neighbour, while not per-se colourblind, has poor colour vision with some deficit in yellow, and

    • by sjames (1099)

      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.

      Actually, that is a combination of using other senses, stepping in a way that allows you to adapt to unanticipated terrain, and learning a different mode of vision that avoids tracking objects of interest with the fovea (which provides detailed color vision but is less sensitive to low light than the peripheral vision). I've done it many times.

  • Obi-Wan Kenobi would be proud.

  • See It Now (Score:5, Interesting)

    by hyades1 (1149581) <hyades1@hotmail.com> on Thursday December 25, 2008 @02:46AM (#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 Col Bat Guano (633857) on Thursday December 25, 2008 @02:47AM (#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).
  • by iammani (1392285) on Thursday December 25, 2008 @02:55AM (#26228745)
    Heres a video of the man walking through the obstacles - from BBC
    http://news.bbc.co.uk/2/hi/health/7794766.stm [bbc.co.uk]

    Ps: Found this after 'Submit'ting to slashdot
  • Video at NPR (Score:2, Informative)

    by eefsee (325736)

    A video of the blind man walking down the corridor accompanies this story at National Public Radio [npr.org].

  • Somebody check this guy's midichlorians.
  • Isn't this a basic use of the Bronikov-method [biopcglobal.com]?
  • 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

  • Everyone knows that blindsight is an extraordinary ability, which can be used to operate effectively without vision. It might be a form of sensitivity to vibrations, acute scent, keen hearing, or echolocation. It even makes concealment and invisibility (even magical darkness) irrelevant to the creature with blindsight.

    Don't believe me? Well, it's RAW [systemrefe...uments.org].

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