Stereoscopic Vision

November 9, 2010 1:43 PM

Is the average person really that dependent upon stereoscopic vision?

I'm listening to an interview (Fresh Air podcast, 26/10/10) with neurologist and writer Oliver Sacks regarding his experience with going blind in one eye. He describes the transition from stereoscopic to monoscopic vision as rather difficult -- his initial experience was a total lack of depth and difficulty with defining objects in their physical space. He describes having difficulty with stairs, pouring glasses of wine, shaking someone's hand, etc.

Is this really a significant issue for other people? I remember learning about stereoscopic vision when I was a kid and becoming very interested in it, I think primarily because it didn't seem to "work" for me. I could walk around with one eye covered and navigate space as well as with both eyes open. I would experiment with this on summer days where I had a lot of time on my hands, so I would spend hours viewing the world monoscopically with no serious consequences.

I have no memory of identifying something in three dimensional space via stereoscopic vision until my late teens (when I became interested in it again). Even today, it's tertiary to other ways of locating objects in their surroundings. I unconsciously place more value onparallax, perspective, and shading.

Are other people as dependent on stereoscopic vision as Oliver Sacks is, or is his case relatively unique? He does describe himself as a lover of stereoscopic vision, surmises that he had unusually strong stereo vision, etc.



Posting in science and nature because that's as close as I can get?

posted by TeslaNick to science & nature (29 answers total)

This book talks about how the writer's life changed for the better when she acquired stereoscopic vision, just to give you the reverse perspective.

I had a lazy eye when I was a kid, and losing stereoscopy (because of the eyepatch treatment) led me to fall down the stairs fairly often.
posted by Sidhedevil at 1:48 PM on November 9, 2010

I can't see stereo, never have, and it doesn't really bother me at all. I gather depth cues from other sources (eg: knowing how big something is). Only real drawback was catching things.
posted by aramaic at 1:56 PM on November 9, 2010

I remember my grandfather, in poor health for some time and for some reason with lessened depth perception, trying to casually set down a glass of water and it almost spilled because he didn't account for the thickness of a coaster.

If you're really focusing on it, I imagine that the movement of your head or changing light will help you understand the depth of the world. You can understand much from how light falls on items, but from these anecdotes, it seems the fine tuning is important - the difference between missing a step and walking down stairs, between a glass tipping over and being set flat.
posted by filthy light thief at 1:56 PM on November 9, 2010

(And on no preview, knowing the difference between a world in stereo and a world mono makes the loss or gain more important.)
posted by filthy light thief at 1:57 PM on November 9, 2010

If you practised as a child, that might be why you can see easily monoscopically. Children's brains are so plastic, that I bet you learned to use perspective and shading cues very fast when you experimented.
posted by lollusc at 2:01 PM on November 9, 2010

According to Oliver Sacks in the New Yorker, about 5-10 % of the population have little or no stereo vision. He describes a woman whose life changed when she acquired it. The article impressed me when I read it for the first time, because it made me realize that I'm among that 5-10%.
posted by Wordwoman at 2:05 PM on November 9, 2010

I took a perception class in college, and one of the professor's favorite exam questions was, "Why do we have two eyes?" There were, if I recall, seven answers, and stereoscopy was only one of them. (I forget them all, but as you mentioned some of them include differences in parallax, muscular convergence [crossing your eyes cues your brain as to depth], differences in occlusion, etc.)

So having only one eye would heavily impact the way your brain perceives the world, and the loss of stereoscopy is only one of the reasons. So yes, generally, losing vision in one eye would be a problem because you would lose all sorts of visual information, including many depth cues, but also lots of other information.
posted by ChasFile at 2:11 PM on November 9, 2010

Sometimes I have to go around without one contact lens in, which essentially gives me stereoscopic vision because my uncorrected eye is legally blind (20/800). It definitely affects the way I feel oriented in space -- depth perception is all messed up, and I feel disoriented.

I would guess the reason you didn't find this disorienting as a child is more about cognitive bias than vision. You were purposefully changing your vision and you were educated about the kind of adaptations you could make and the changes you could expect. That's much different than unwillingly losing part of your vision functionality.
posted by yarly at 2:13 PM on November 9, 2010

Born cross-eyed, I've never had stereo vision. I can't play any game involving catching or hitting a ball, and never ask me to reach across the table and fill a glass. I don't drive but that's for a whole set of reasons of which eyesight fail is only one (I do ride a bike).

In recent years though I've been watching with dismay the resurgence of 3D movies, games and other entertainment, because it's all gibberish to me.
posted by zadcat at 2:17 PM on November 9, 2010

Like Sidhedevil did, my daughter wears an eye patch for part of each day to treat amblyopia. Even after almost 18 months of daily patching, it is clear that operating without stereoscopic vision affects her depth perception and her movement through space.

Some of that can be attributed to the fact that her stronger eye is covered. But the doctor made it clear that while she is wearing the patch, and he explicitly stated "without stereo vision," she would have to be extra-careful with physical activity. Watching her dance with and without the patch is remarkable.
posted by Lulu's Pink Converse at 2:18 PM on November 9, 2010

Find out first-hand: get an eye patch, wear it around the house. You're then dealing with two things -- loss of stereoscopic vision, and a limited field of view -- but in our experience one will always go hand-in-hand with the other.
posted by davejay at 2:23 PM on November 9, 2010

Never had stereoscopic vision, never noticed it as a problem (except in school, when playing games that involved hitting a moving ball with any object smaller than a tennis racket - tennis itself I'm fine with). I can navigate in the world without any trouble, and I'm guessing that my brain learned to adapt well enough at a young enough age that it's just never been a problem. (Except for 3D movies, which, ugh.) So yeah, I'd say that it's totally possible your brain just learned to do the same thing, even when it could use stereoscopic vision if it needed to.

I can't actually conceive of what stereoscopic vision would be like - it's like trying to imagine another colour - and if it was possible to take a pill and acquire it tomorrow, I probably wouldn't. Having the ability to switch eyes at will is useful to me in a way I'm quite fond of!
posted by Catseye at 2:31 PM on November 9, 2010

I've never had stereo vision, you kids and your fancy newfangled doodahs.

When I was in my early 20s I developed the habit of going around with one eye closed, probably in an effort to reduce distraction. I stopped when I realized how weird I must look. But the only difference to me was that my field of vision was narrower.
posted by tel3path at 2:35 PM on November 9, 2010

I've been blind in one eye my whole life. I still drive, pour beverages, walk up and down stairs, etc. without incident. I am kind of clumsy, but I don't think that's a vision thing, I think that's just garden-variety clumsiness.

A few things I've noticed I have a hard time doing: watching 3-D movies (yeah, that's impossible but no big loss), those "Magic Eye" books, putting mustard on hot dogs from one of those pumps (I have to get my eye directly above the pump). I also tend to rest the pitcher/bottle/whatevs on the lip of the glass when I pour.

BUT: I can shoot a gun like nobody's business! First time I tried, I hit the neck of a beer bottle from 20 feet away.
posted by rabbitrabbit at 2:43 PM on November 9, 2010 [1 favorite]

Data point: A friend of my father's lost an eye at a fairly young age. He ended up teaching art at my high school. He was also an accomplished artist - mainly etchings/drawings of architecture and landscapes, i.e. stuff that depends on getting perspectives right.
So, stereoscopic vision is apparently not even necessary for drawing/sketching 3D stuff.
posted by The Toad at 2:50 PM on November 9, 2010

I would say the average person benefits greatly from stereoscopic vision.

I unconsciously place more value onparallax, perspective, and shading.

Unless you're moving around you're going to need both eyes to perceive differences in parallax. Perspective is easy to misjudge and is the basis of some optical illusions- is that a large object far away, or a small object close up?

I imagine you could use differences in focus to help you perceive depth without both eyes, but it would only work at short distances, and would have similar problems to using perspective.
posted by Pruitt-Igoe at 2:53 PM on November 9, 2010 [1 favorite]

My father was blind in one eye, and you would have never known it. But there's a mental aspect, as well.

It really, really, REALLY aggravates him when he runs into situations where lack of stereoscopic vision hinders him in a way he can't control or adapt to. First time at a 3D movie at Disney World, and he pitched an embarrassing fit, berating a Disney employee. He becomes quickly belligerent whenever we play sports where his weakness is an issue. A simple foot race is no big deal. Tennis, however, or ping-pong, are psychological ordeals I simply will not repeat with him. God help you if, fairly or unfairly, he thinks you're taking advantage of him.
posted by Cool Papa Bell at 3:00 PM on November 9, 2010

I had a weird misconception about stereoscopic vision when I was younger, which is that without it the world is some sort of crazy Picassoland devoid of perspective and 3-dimensional space. I was so confused as a kid after wandering around with one eye closed to find that everything looked dissapointingly similar. This in turn led me to think that maybe I was different, maybe I didn't have correct stereoscopic vision and other strange conclusions. It wasn't until I was randomly forced to spend a couple days with only one contact in rather than both that started to notice differences. It doesn't really affect perception much at all, but processing tasks (as many who cannot see stereoscopically have commented already). Anything that requires you to unconsciously and quickly calculate distance is impossibly harder. To me the difference is closer to comparing a pro athlete with an amateur.

It's interesting because it really highlights the difference between how we perceive and process space. Try closing one eye and drawing a picture of what is around you. It's still possible. You construct space on the page through perspective technique anyways. Hitting or throwing a baseball is a totally different game.
posted by tmthyrss at 3:04 PM on November 9, 2010 [1 favorite]

I'm another one who's been monoscopic all my life and there have been no issues for me other than optometrists enjoying watching my eyes take it in turns and the knowledge that I'll never see a dolphin coming popping out of a stereogram. No problem with depth perception at all and can happily play badminton with as greater degree of success as my stereoscopic opponents. I guess if you've never known different then it's easy because as people above say, the brain of a child is plastic and adapts very well.

I may form a band called "My Stereoscopic Opponents"
posted by merocet at 3:09 PM on November 9, 2010

Machine vision algorithms include methods to get depth info from the movement of one camera, since two close in time shots of the same scene is really the same information that two camera's give. Perhaps in you trials your readilly pulled on a similar tactic, especially since you mention moving about.
It could be that some brains are wired in a way easier to do that tactic than others, but quite hard to test this ut.
posted by oblio_one at 3:38 PM on November 9, 2010

I've got a good friend who lost one of his eyes at about 12 or so, and the only complaints he's got is that he can't enjoy 3D movies (he's spent some time in the effects business, so it matters), and that he doesn't have a spare.

And he had reason to get philosophical about it recently, 'cause another friend's son lost an eye in a BB gun accident recently, so there was much communication and discussion on the topic.
posted by straw at 3:44 PM on November 9, 2010

I had a hell of a time with certain sports- baseball was really hard, and squash and racquetball were nearly impossible. Other than that, really not a big deal.
posted by jenkinsEar at 4:03 PM on November 9, 2010

I lost the vision in one eye at the age of 30 - I found it to be a difficult transition for about eighteen months. After the transition period it's pretty much no biggie. I don't play games that involve objects being thrown at me or games having to throw objects at targets (basketball for example) or watch 3D movies and that's about the extent of the effect on my current life. During the transition period I would spill things, trip over curbs, trip over chairs, trip over pretty much everything. Oh, and even now it drives me BONKERS when people throw things at me - especially keys.

I think the biggest thing is, if you lose it as an adult, the anxiety about the change in your vision and the effect it will have on your life. It seems/seemed to me that it changed everything and then nothing at all. There was a very intense period of physical and mental adjustment and then I adjusted and now it's just fine, not optimum, but fine.
posted by PorcineWithMe at 4:07 PM on November 9, 2010

I have never had stereoscopic vision. I am not able to focus on something, but instead, everything is in focus all the time.

Anyway, despite my lack of stereoscopic vision, I still bicycle at great speeds without injuring anyone. I also pour drinks (with great amounts of concentration).

I can reach out and grab stuff, but that's mostly because I pick up on shadows and other light-based cues. I also am familiar with the size of objects in my environment. This allows me to judge the distances based on size of the object.

However, I am terrible at ball based sports as catching/swatting/otherwise manipulating a ball not in my control is very hard for me to do.
posted by 47triple2 at 5:02 PM on November 9, 2010

Due to some chronic eye infections when I was very, very small, I had about a year without much vision at all. I can only assume it was at some critical development period, because I did not have much in the way of depth perception via stereoscopic vision and had to rely on other cues (detail and texture, mostly) as a kid, but I wasn't great at things coming at my head.

Then, around nineteen, due to neurological insult, I started processing in stereo. This was extremely disorienting for a while. Everything leapt out at me or was plummeting away. After a couple of months, I adjusted and my eyesight, according to the usual eye charts, was better than before. I could catch things now, which was nice.

I occasionally have some eye problems that require one eye or another to be taped up. I switch back and forth from mono to stereo and back pretty quickly now, maybe half an hour of oddness. Narrower field of vision is definitely an issue and near-distance things, between, say, a foot and five feet, are problematic. I generally compensate with a very slight head turn.

I still do not like stuff being thrown at my head.
posted by adipocere at 7:01 PM on November 9, 2010 [1 favorite]

Depth perception isn't an on/off thing, either. I didn't know this until a few years ago, when I had to undergo an exceptionally thorough physical exam as part of a pre-hire process. They gave me a depth perception test where your score ranked between 0 (none) and 10 (super awesome).

I didn't care, because I was going for a sysadmin job, and honestly. But the nurse was very kind, and sort of helped me cheat. She was all, "Are you sure you don't see, maybe, a 2?"

I don't have any neurological issues. My eyesight is terrible (+7.5) but it's equally terrible in both eyes. I just have virtually no depth perception.

It's not that big a deal, although the new fad for 3D movies is wasted on me. And please do not toss something for me to catch, I'll happily walk over and take it from your hand, thank you!
posted by ErikaB at 7:24 PM on November 9, 2010

rabbitrabbit, I'm a good shot too! I have a nice handful of trophies on my shelf. You only have one eye open when you shoot, anyway.
posted by tel3path at 12:18 AM on November 10, 2010

I'm also monoscopic although both eyes work -- the left one's just always been much weaker and for whatever reason the eye doctors always prescribe the same lens for both eyes.

I've read that people like us learn to use environmental cues to navigate in a 3D world. Never had a problem (though maybe this lack explains my failures with all that hand-eye athletic stuff like tennis and baseball). But 3D movies are an irritation, like those stupid Magic Eye posters they used to have at the mall, with people staring at blobs saying, "Can't you see it?"

Only real trouble is at the DMV when they have you read the eye chart with one eye covered, then repeat with the other eye covered -- now I just memorize the chart, while waiting in line.
posted by Rash at 2:53 PM on November 10, 2010

My boyfriend has been blind in his right eye from birth, and for most things you'd never know. He tends to brake a little hard at stoplights because he can't quite judge the distance and errs on the conservative side, he has a hard time getting a screwdriver back into a screw head when it slips out, and he catches thrown objects about as gracefully as I do (I'm a natural klutz). He also doesn't realize, when I'm driving and he's navigating, that the sun is reflecting off the face of his iPhone and into my eyes, because reflections from the right are a non-issue for him when he's driving. Complaining about the prevalence of 3D movies is a bonding activity for us, as he can't see them and they make me seasick and headachy.

It's unnoticeable enough in daily life that his dad used to yell at him for using the wrong eye to sight down a gun until he finally pointed out that he *had* to use the wrong eye.
posted by telophase at 3:02 PM on November 10, 2010