Cognitive Daily

ResearchBlogging.orgPhilosophers have wondered for centuries whether someone who was blind from birth would “see” the world in the same way as people with normal vision. After all, there’s much more to perceiving the world than properly functioning eyes. Think of it: otherwise all you’d need to do is strap a camcorder to a car and you’d never have to learn how to drive!

But there are surprisingly few cases of people who were born completely blind and then had their sight restored after many years of blindness. If a patient can be cured, it’s usually done quite early in life. But a few cases have emerged in recent years, the most promising of which was a woman from India who goes by the initials S.R.D. She was born almost completely blind, able to tell day from night but otherwise unable to perceive anything visually. At the age of 12, she underwent surgery to correct her vision, which was successful in one eye. Almost overnight she was able to experience a whole new visual world, and she has had vision that was correctable to near-normal for the past 20 years.

Although researchers weren’t aware of S.R.D.’s case until recently, her mother told a team led by Yuri Ostrovsky that it took several months for her daughter to be able to recognize basic objects and navigate the world using sight. Eventually she completed seven years of school, married, and now works as a maid. She can get around her town by herself and walks without a cane.

But what Ostrovsky’s team wanted to know was whether S.R.D.’s visual system was truly normal. Using a laptop computer, they gave her ten different tests of the visual system, including visual memory, shape matching, depth perception, face/nonface discrimination, face identification, and gaze estimation. They gave the same test to another woman from India who had accurate vision and the same education level and social status. They also tested several Americans with similar visual acuity to S.R.D. (about 20/200).


Overall, the researchers found that S.R.D. could complete nearly all of the tasks just as accurately as the others, although anecdotally it took her about 5 to 10 seconds longer than the people who had never experienced blindness. There were two exceptions. She wasn’t quite as good at recognizing faces (though she still was more than 75 percent accurate), and she had a peculiar difficulty in judging gaze direction. Take a look at these photos:

i-e2aa8d15c87c481fb9b98ded75250939-ovstrovsky.jpg

For photo 1, S.R.D. would accurately say that I’m looking to the left, just like everyone else would. But in photo 2, she wouldn’t be able to perceive that I’m also looking to the left. She could only judge gaze direction based on head orientation, not eye orientation. Even people with equally poor visual acuity as S.R.D. were easily able to do this task. We’ve discussed gaze direction before, and it looks like what S.R.D. is doing is defaulting to the most basic system for judging gaze — head orientation. People who’ve always had normal vision still make mistakes when the eye-orientation and head-orientation conflict. Somehow S.R.D. just never learned to use eye-orientation when head-orientation is ambiguous.

Still, all in all, S.R.D.’s vision was strikingly normal, even after being completely blind for the first 12 years of her life!

Update: Michael Bach and others bring up an interesting point in the comments. There have actually been several studies of individuals who have had sight restored after being born blind. But S.R.D.’s case is unique because of the length of her visual deprivation and the time that passed since vision was restored. Take a look at this graph from the article:

i-a5c4728684e1fd12129b5a3394954c5d-ostrovsky2.png

It shows both of these factors for a number of different studies, and as you can see, in all other cases, either the study was conducted very shortly after vision was restored, or the individual didn’t experience blindness for a very long time. Finding a case like S.R.D.’s is quite unusual!

Yuri Ostrovsky, Aaron Andalman, Pawan Sinha (2006). Vision Following Extended Congenital Blindness Psychological Science, 17 (12), 1009-1014 DOI: 10.1111/j.1467-9280.2006.01827.x

Comments

  1. #1 Peter
    November 11, 2008

    I’m reminded of something I once read by Oliver Sachs (which is, luckily, online):
    http://www.oliversacks.com/marsex.htm

  2. #2 Marina Martin
    November 11, 2008

    I’d be far more interested in her perceptions of beauty, or if she could differentiate between what we’d consider “normal” and “not normal” visually … i.e. if she was shown a photo of a green human, would she be able to identify it as not real?

  3. #3 Rafael C.P.
    November 11, 2008

    This is a very interesting topic. If you stop to think about it, they (healed blind people) didn’t even know what is that “vision” thing (maybe it’s not SRD’s case, since she could see luminosity). Imagine you wake up and have a new sense. No, you can’t imagine! If you try, you’ll be trapped thinking in terms of your existing senses (like imagining having a sonar but all you can think of are *images* representing it). The mistery of qualia!

  4. #4 Rafael C.P.
    November 11, 2008

    Ah, one more thing. About the gaze recognition, it needs good vision resolution. Did they try to make she recognize other small details like this? Maybe her cortex is full of other sensory data (12 years!!) and vision will never get the same area of normal sighted people, so it can’t be very precise and detailed (like normal sighted people are not very precise with audition).

  5. #5 John L.
    November 11, 2008

    You’re actually looking to your right in the pictures. Whomever is viewing you would see you looking to their own left.

  6. #6 Mary
    November 11, 2008

    The Washington Post had an article about 2 or so years ago about the spatial sense a (particular) blind person had. It showed drawings by this person that had reasonably accurate perspective and spatial relations. Amazing really; I don’t remember the details.

  7. #7 Stuart
    November 11, 2008

    Robert Kurson wrote a book called “Crashing Through” about a man whose sight was restored after many years of blindness. He had a lot of difficulty with his depth perception and also with recognizing faces.

  8. #8 Ronnie
    November 12, 2008

    My fiance lost sight in his left eye at age 11 in an accident. He has no depth perception but is a phenomenal artist and has won many awards for Black/Grey tattooing.He now paints quite beautifully.He had been told that his sight could be restored 10 years ago but isn’t sure what he would gain or lose and if he would have to “relearn” sight. I’m curious myself as well as wondering about personality changes involved with losing/restoring sight??

  9. #9 Michael Bach
    November 12, 2008

    Interesting findings, though very different from those by Gregory 1963: Recovery from Early Blindness (PDF available at the top right). A dark story there, and that subject was not able to deduce 3d-shape; and then he took his life because his good coping with blindness was no longer a success story for him (sorry, this is strongly abridged). The difference may be due to the fact that Richard’s subject was 52 years of age in contrast to 12 here, and her 20 years of subsequent learning.

  10. #10 lylebot
    November 12, 2008

    There was an article about this in the New Yorker a while back. It was a profile of someone who had been thought to be blind since childhood. A doctor realized that it was actually a correctable condition. IIRC, the patient’s visual cortex had not finished developing at the time of the blindness diagnosis, and it was decades in between that diagnosis and the corrective procedure. It’s a rather sad story of someone who can suddenly see but can barely process anything.

    (Actually, I think it was the Oliver Sacks article linked above, but that link is just an excerpt from the entire piece.)

  11. #11 Nagendra Pratap Singh
    November 12, 2008

    Hard to say anything without being there. Maybe the woman’s eye misses small details as the eye direction but can see a much larger object like a head. Something like myopia or even more because the muscles were never trained.

  12. #12 Pablo
    November 12, 2008

    Actually what happened is quite known: http://www.nlm.nih.gov/medlineplus/ency/article/001014.htm

  13. #13 Nigel
    November 13, 2008

    This is interesting stuff. Baron-Cohen draws a link between an impairment in following other people’s gaze direction and autism. I wonder if there are any signs of autism in this patient (it is not mentioned in the article). I believe I read somewhere that autism is more common amongst the congenitally blind than in the general population, presumably in part because they cannot get the social cues from seeing gaze direction that other children do, and which are probably a significant factor in helping sighted children (even those who will become blind later in life) to learn about other minds. However, not all congenitally blind children are autistic, so probably many are able to compensate for the loss of this gaze direction information early in life with social cues picked up by the other senses, and that may be so in this case.

    Incidentally, Molyneux’s Question by Michael J. Morgan (Cambridge University Press, 1977) is an excellent book that discusses the history, psychology and philosophical ramifications of congenitally blind people restored to sight in considerable and sophisticated depth. He considers not only the case reported by Gregory (mentioned in one of the comments above) but many others, going back to the 18th century (when the relevant cataract removal operation was first performed), and explores the broader implications of these cases for the theory of vision and spatial perception.

    With regard to Ronnie’s comment, it is my impression for what I have read about this (in Morgan’s book and elsewhere) that the sort of vision and personality problems described by Morgan (and Gregory) in blind people restored to sight are specific to congenitally blind patients. If your fiancĂ© was normally sighted until 11 I doubt whether there is any reason to expect him to respond in the same sort of unsatisfactory way (although there might be other issues, of course).

  14. #14 Edward Clayton Rowe
    November 15, 2008

    I find the statistics on facial recognition the most fascinating.
    Was this a test of whether the subject recognized non-photographic images as faces, or whether she recognized separate photographic images as representations of the same person?
    Now, I’d add that, as a caregiver for individuals diagnosed with autism, I often noticed a dissonance between head orientation and attention, which I usually interpreted as part of the “social maladjustment” of the diagnosis.(I.E.”I’m not looking at you, but I am paying attention to you.”)Indeed, that dissonance was often the way we recognized such individuals in public, since our program tried to avoid the situations where vans full of clients trooped into stores and restaurants (“social norming” was the term that was used).
    Thanks to Pablo for the comment to Ronnie’s thread. I’m writing a sf story about a personality downloaded into a fresh and healthy body. This personalty has had age-related deterioration of sight and hearing. The personality quirks he has then acquired in response to that deterioration could then be expected to extinguish themselves when they are no longer positively reinforced,when they are no longer part of his coping strategy.(Not an easy concept to communicate in fiction, but, hey, that’s the real challenge.)

  15. #15 Lisa
    November 20, 2008

    I’d like to know if 20/200 is SRD’s corrected vision, or uncorrected, and was she wearing corrective lenses during the test? If so, did this correct her vision to 20/20? If that’s the case, we can probably rule out lack of visual accuity as the cause of her inability to recognize pupil orientation. If not… well, I honestly couldn’t say, since my own vision is 20/400-something without glasses, and not quite 20/20 with them. Take my glasses off, and I can’t even tell whether someone’s actual head is facing right or left, let alone their pupils! Move them more than about 30 feet away, and it becomes more a question of “What person? Where?”

  16. #16 Dave Munger
    November 20, 2008

    Lisa: It’s corrected to 20/200. But remember, she’s looking at a computer screen just 30 inches away, not someone 30 feet away. I’m not sure how big the pictures were, but they would certainly be bigger than my example photos. People with similar visual acuity could easily do the task. My vision is much worse than 20/200 and I can do the task when the photo is bigger than about six inches across.

  17. #17 Ronald
    May 22, 2009

    This is very interesting. My daughter has been blind from birth with ROP (detatched retinas). Her eyes are otherwise healthy but she has seizures. At 16 yrs old her mental level is several years lower but she has learning disabilities with the consept of letters and numbers (braille is essentially a number/letter memory thing). Her memory is excellent (amazing at times!)and her social skills are OK. I have often noticed and commented to the professionals that some of her actions mimic autism. They claim that is not uncommon because they are trying to stimulate other senses. Also I had read that persons that have never seen have not developed the ‘sight’ regions of the brain and that if vision was restored they might not be able to develop useful vision. Maybe that’s why there seems to be more research into aids for the blind than cures for the problem. Also I assume technological advances come quicker from fringe research (laser location, measurements and the like in real time)rather than surgical procedures for the fragile eye we sighted take for granted.
    Thanks for the insight (no pun intended!).