Saturday, November 2, 2013

Motion parallax (March - October, 2012)

So, I started therapy with Dr. Richard Kavner. I kept coming for sessions two or even three times a week, though later I reduced it to once a week for financial reasons. When given exercises, I diligently did them at home, but with considerably less enthusiasm than I did during my own experiments. This, by the way, was a huge mistake. I notice over and over how essential can be quantity.

Even though it looked like there was a little bit of improvement, gradually I lost even more enthusiasm. The first 20-30 sessions passed, I decided to continue therapy, and there was no end in sight. My vision was O.K.; however, now, I was "blessed" with double vision, which became a very pronounced issue after an initial period of VT. My right eye was more thoroughly unsuppressed and was actively fighting with my left eye. At the same time, perceptually everything was about the same. It looked like we were just doing a little bit of "polishing"; fundamentally, the "3D" was the same as before.

Whenever I did exercises with various stereograms "hanging in space", I would often receive instructions to sway my body left and right and to see, if the imaginary stereogram were moving "the same direction" or "the opposite direction". I did my best, although this always seemed to me a stupid exercises, as "obviously", if you sway right, everything would move to the left, and vice versa. Gradually, though, I became better at doing those exercises, and recognized, that sometimes the image would move "in the same direction", and sometimes --- "in the opposite".

Then one day, probably in September-October, 2012, I was walking down the street in Brooklyn. There were cars parked along both sides of the street. I was walking and, as usual, looking at the street, the cars, the trees, notice the depth, the distances, and so forth. Now, since I was walking, so to say, forward, the cars were perceptually moving back for me, much like if you look out of a train window, everything will be moving back relative to you. At some point I looked at a car parked on my side of the road, and noticed in the periphery, that the cars on the opposite side were moving forward. They were moving in the wrong direction!

This made no sense. The cars on the opposite side of the road seemed to be moving forward when I was going forward, so long as I looked on the cars parked on my side of the road. However, if I looked further away, perhaps at the buildings on the other side, then all cars seemed to be moving backward, relative to my movement. That is, it mattered where I was looking.

This was an entirely new phenomenon. Prior to that, the direction of my gaze had never made much difference. Of course, if I turned my head or my body, I could look at other things. However, it my no difference, which particular object I was looking at; it was much like moving a mouse pointer on a computer screen: "visual focus" simply meant "attention". Yet in this situation, shifting my gaze while moving changed the direction in which the cars (that I saw in the peripheral vision) were "moving": from backward to forward. It really mattered, what I was looking it; and, in fact, I received immediate feedback as to what I was looking it. Of course, at first it was not easy to trigger this parallax effect: it had to keep looking at a particular car or object for 5-10 seconds before the effect kicked in. But I immediately went for a walk, and after 1-2 hours I was able to reduce the time to less than a second. That is, if I started looking at some object while walking, after about 1 second I felt that the parallax effect started working somewhere in my visual system, and lots of objects in the periphery suddenly started moving, one way or another. On the following days this parallax effect only got stronger; and it has been with me ever since. Now I can hardly imagine, what I "saw" prior to that. The best explanation I have is that prior to discovering this new "parallax effect" I had never been looking at anything, or at least not consistently. True, I had written in this blog about "binocular focus", but I think that I had been very imprecise with my focus, sometimes looking a little in front of an object, sometimes a little behind, and easily loosing focus when either I or the object was moving.

Of all the changes that I have so far experienced in vision therapy, that was perhaps the most significant one. It was almost as surprising as the original discovery of stereopsis. Almost all of the other changes during my vision therapy have been relatively minor, incremental; this one was radical, black-and-white kind of change, after which the new mode of seeing quickly and completely replaced the old one.

If I take off the contact lens on my eye, the fusion get much worse, and the parallax effect does not work that well. But this is still not the same as it was in the past. Now the parallax effect makes complete sense. I could even draw a diagram. Of course, if I am walking along the street and looking on the car on this side, perceptually the cars and the buildings on the other side would be moving in the same direction. Yet a little more than a year ago this was virtually beyond my imagination.

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