Stereopsis

While reading Oliver Sacks' 'Minds eye' I found myself astonished at how little I actually cared about stereoscopy before. Test show that my stereopsis is feeling quite good; I don't think I ever had trouble with it, but I just never gave it any credit, taking it for granted, as most of us do. I never understood the fuss about 3d monitor, even though I like 3d movies at the cinema (but more on that later)

 However, as I started to experiment with stereoscopic vision, or rather, because I became aware of it through my reading, and started to experiment with it, I was amazed at what magnificent difference it actually makes.
 Try looking at the world with one of your eyes closed and you will probably notice how flat it is without stereo vision. It is, in fact, often hard for me to tell if the object I see is concave or convex if I close one of my eyes while looking at it. In some situations it is virtually impossible to tell the distance between objects, I think it might also prevent from manipulating objects in some situations. Of course human brain can use many 2-dimension cues to help with those tasks, but it is not quite the same.

Here you might be able to see the teapot, a cup and a window frame. Or you might not. But you can never see any of that on this picture (that is - random dot stereogram) if you lack stereopsis.

Now, I feel bad about it, but as I realized that some 5% of overall population lack stereoscopic vision, sometimes being totally unaware of it, I suddenly became proud of my quite imperfect overall  but still strongly stereoscopic vision. As I realized that most people with strabismus fail to develop proper binocular vision, I remembered a story.

There was this smart-pants girl who mocked me for liking Avatar movie; she criticized my taste and criticized the film - she called it bland, naive, second-class and basically just stupid, meant for people who are easily attracted to flashy pictures and don't care much for actual depth, story or proper acting techniques.

I tried to explain that most of us were excited because of the next-gen technology this movie demonstrated, and how I felt amazed by the mastery with witch 3d elements were featured. I actually wanted to touch some pollen as it flew in front of me, the illusion of it being real, 3-dimensional both stunning and surprising.

She would have none of that, saying that these were just flashy pictures seen before and elsewhere many times. She continued on, pointing out that I was fooled and only excited because of the marketing fuss around this movie; she is still strongly convinced that this movie has nothing even remotely interesting from artistic or technological points of view.

I must confess I was a bit baffled at this, but figured that I, indeed, must be the kind of person who gets easily distracted by colorful pictures and somehow managed to overlook the facts about this movie, even though I had always considered myself a bookish kind of person. I wouldn't care for Avatar movie at all, were my senses, my brain not so delighted by stereoscopic depth in some scenes. Even though 3d movies are known for over 50 years now, rarely do we get to see something so - pretty - done with it.

And now of course I realized that MAYBE this girl, who has had noticeable strabismus for her entire life, could have never see what the rest of us, with our binocular sight, could see. She mentioned seeing 'images too bright and colorful' to make sense when she attempted to see 3d movies.That would be it, of course - people with two functional eyes lacking true stereopsis usually end up 'switching' between their eyes many times per second. Now if such person would try to wear 3d glasses - he would naturally see colored images lacking any depth, just being more irritating because of the color difference.

So, for all her pride and knowledge and education and snobbishness she could have been simply unaware of what others saw, yet was strongly opinionated and vocal about her judgement.

I believe this if often the case in many other situations as well.

Colors

I've been reading Oliver Sacks books this week - I find them very insightful and entertaining. One story in particular got me excited.

This was a story about colorblind painter. Well, apparently he was not at the least colorblind for the first 40 years of his life, managed to build himself prominent career and gained some fame in his chosen profession  but then, after minor accident, lost the ability to see the colors.

 As it is further explained in the book ('An anthropologist on mars'), his 'receptors' - his eyes and his brain's ability to analyze wavelengths of colors was undamaged. However, the part responsible for 'understanding' colors, the one that allows us to recognize colors in context, the one, that apparently, lets us see red apple as red both in fluorescent lights and in the sunset (even though 'physically' we get very different wavelengths on our receptors in those circumstances) got fried.

What got me exited is that I remembered this one day when I was heavily loaded on shrooms and weed, and as I was sitting on a bench staring at the concrete pathway in front of me I realized that I can no longer tell its color or, in fact, its texture. I could not make my mind whether I see sandy path with little gentle slopes, nicely yellowish in color, only made grayish by surrounding twilight - or was it gray concrete path with little shadows from the leaves above, only made slightly yellow in color by bright night lights.

 In a moment, I could no longer tell whether I saw little twigs and pebbles lying on it or crevices and shallow depressions. I stared at the black shapes on a light background but I could no longer tell if they were shadows or some real objects, whether they had depth or none whatsoever.

 As I was trying to made my mind about this, my brain started to flash possible interpretations of this simple scene in front of me in sort of stroboscopic succession. One moment I saw a twig, the other moment I saw a crevice. The pathway was sandy, yellow, blue, gray and then pink and then gray again, in no way helping me to understand what I was seeing.
Granted, I KNEW and remembered that I was looking at concrete pathway, so in my mind I remembered it should be gray. Yet I didn't see it as gray, and what's worse, I could not decide about shadows - in everyday life shadows help us navigate the world greatly. But when 'understanding' of colors gets crazy like this, you suddenly start to mistake dark shapes on the ground for some solid objects.

 This confusion is what Sacks' patient described in detail and I was fascinated by the fact that I can now actually tell what part of my brain was most affected in that trip.
While it was fun and enlightening in many ways, I was actually relieved when this effect was gone in some 10 minutes. As my 'V3' started to operate normally I was able to stand up from the bench and continue my walk.

I am somewhat amused by the fact that now, in retrospect, having read this book, I know what was happening to me back then.