Comments on: Benefits of Stereo Vision You Didn’t Know About http://reubenkrabbe.com/wordpress/benefits-of-stereo-vision/ Whistler Ski and Mountain Bike Photographer Thu, 06 Oct 2011 07:48:06 +0000 hourly 1 http://wordpress.org/?v=3.0 By: Josh Krabbe http://reubenkrabbe.com/wordpress/benefits-of-stereo-vision/comment-page-1/#comment-3734 Josh Krabbe Thu, 18 Mar 2010 06:09:48 +0000 http://reubenkrabbe.com/wordpress/?p=408#comment-3734 Alright, here's something weird. I close one eye, hold a finger approximately 30 cm in front of my face. I then focus on the other end of the room... What happens? Well, according to what you might think, and what Reuben is suggesting I see the finger out of focus when focused at a longer distance. What I noticed though. That finger appeared (at least to me) to be more out of focus in the horizontal plane than in the vertical plane. Now each eye is circularly symmetrical in the vertical and horizontal planes, or at least to a very good first approximation. That means there shouldn't be a difference in horizontal and vertical focusing of one eye, but because the brain normally processes images with the help of it's stereo partner, perhaps when it looses that help there's a difference in it's image-processing power. The visual cortex is perhaps better prepared (probably, walking around with one eye closed a lot would un-train this) to deal with stereo vision than non-stereo vision. Here's what I propose... We've got a visual cortex that is trained to process images in stereo and it's so good at it. The neural pathways and shape and image reconstruction algorithms running in our brains are trained to do the correction in the vertical with a lesser degree of stereo-provided help. When we loose the input to the stereo-helper, those neural pathways aren't trained as strongly to operate the same way. Who knows the exact source of this confusion, perhaps the brain has some measure of the expected depth of that finger, and the focal point, it expects to see it doubled side to side but then doesn't. Perhaps it's shape forming capabilities are based on a reliable subset of rods and cones that isn't uniformly distributed across the two retinas. The gist of it is this: What that visual cortex is well-trained to process, it doesn't get. It's interesting to note then, the effects of how the brain deals with this incomplete information, I'm sure it could be trained otherwise, but unless I'm going to try to make a living from what I can see this isn't really a worthwhile investment of my time. It brings to mind this clip from an excellent podcast. Start at about 16 minutes, and listen until at least the end of the section on phantom limbs. http://rkp.me/phantomlimb Of course I'd recommend listening to the whole show. Alright, here’s something weird.

I close one eye, hold a finger approximately 30 cm in front of my face. I then focus on the other end of the room…

What happens?

Well, according to what you might think, and what Reuben is suggesting I see the finger out of focus when focused at a longer distance. What I noticed though. That finger appeared (at least to me) to be more out of focus in the horizontal plane than in the vertical plane. Now each eye is circularly symmetrical in the vertical and horizontal planes, or at least to a very good first approximation. That means there shouldn’t be a difference in horizontal and vertical focusing of one eye, but because the brain normally processes images with the help of it’s stereo partner, perhaps when it looses that help there’s a difference in it’s image-processing power. The visual cortex is perhaps better prepared (probably, walking around with one eye closed a lot would un-train this) to deal with stereo vision than non-stereo vision.

Here’s what I propose… We’ve got a visual cortex that is trained to process images in stereo and it’s so good at it. The neural pathways and shape and image reconstruction algorithms running in our brains are trained to do the correction in the vertical with a lesser degree of stereo-provided help. When we loose the input to the stereo-helper, those neural pathways aren’t trained as strongly to operate the same way. Who knows the exact source of this confusion, perhaps the brain has some measure of the expected depth of that finger, and the focal point, it expects to see it doubled side to side but then doesn’t. Perhaps it’s shape forming capabilities are based on a reliable subset of rods and cones that isn’t uniformly distributed across the two retinas. The gist of it is this: What that visual cortex is well-trained to process, it doesn’t get. It’s interesting to note then, the effects of how the brain deals with this incomplete information, I’m sure it could be trained otherwise, but unless I’m going to try to make a living from what I can see this isn’t really a worthwhile investment of my time.

It brings to mind this clip from an excellent podcast. Start at about 16 minutes, and listen until at least the end of the section on phantom limbs. http://rkp.me/phantomlimb Of course I’d recommend listening to the whole show.

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