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Shifting in a Triangle
#46
arocarty Wrote:
David Wrote:I think the visual system requires a certain amount of data in order for it to be able to orient and focus correctly. And I think the only way it can get enough data to orient itself is if there is a fast enough stream of data. And I think a new set of data for that data stream is created each time the eyes make a tiny shift. That last part might be known and verified somewhere online, but I admit that's a lot of maybes.

It may not be that the data set is always so new; with a very tiny shift it would be almost identical, but that it is then processed and transmitted in turn by different photocells. So, even though there's sometimes an almost identical image on the retina, the refreshment requirement is being fulfilled because different cells are taking turns processing the input with each movement.

That being said, however, the rods in the periphery require a somewhat larger shift to be refreshed, which is why the peripheral can fade out some time before the central cones, which are structurally closer together. So what satisfies central vision may not always satisfy the peripheral (and cause some form of 'tunnel vision').

How fast is fast enough? Like many other aspects of the visual system, there's probably a lot of inter-individual variation. We don't have direct control over our involuntary fixation movements (MIcro-saccades, tremor, and drift). We do have control over voluntary saccades, but even with those, we don't want to compromise too much detail for speed. Bates observed that trying to shift more than a few times a second would begin to cause strain. So in terms of our voluntary movements, it can be counterproductive if we try to shift too fast.

I didn't know that about the rods requiring a larger shift. That does make sense, with the way you can create tunnel vision by looking at a small area for too long without glancing away far enough. And one glance will do it - I believe Bates mentioned that people with good vision will periodically glance away from a small area they're studying even if they don't realize they're doing it. I feel like I should be studying those kinds of things already known in optics and physiology and neurology and wade through the useless stuff (useless for our purposes, anyway) in order to find important things like that.

As far as fast enough, I don't remember offhand Bates saying a few times a second (any idea?), but that does sound roughly right. It's always nice to verify things like that, even if Bates did put a lot of time into the research. I don't know, I have a hard time counting. I think faster than 3 or 4 times a second is possible, but that's certainly enough to start with anyway, and a lot better than 1 per second. At some point the saccades and microsaccades kind of start meshing together as the distance and frequency of each gets closer, so that makes it hard to count too.
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"Half of our funny, heathen lives, we are bent double to gather things we have tossed away." - George Meredith
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#47
this was already said in the blogs.... also the information you gave us was shown in the book, Perfect Sight without glasses, except the information below the picture of the eye chart. but i don't know where you got the below information from. the above, i didn't understand it when i've read it from the book though.
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#48
David Wrote:That does make sense, with the way you can create tunnel vision by looking at a small area for too long without glancing away far enough. And one glance will do it - I believe Bates mentioned that people with good vision will periodically glance away from a small area they're studying even if they don't realize they're doing it.

Yes, interspersing longer glances away will help keep those peripheral cells more engaged. Sometimes, when driving, for instance, I find myself getting hung up on fixating too long on a tiny spot (like the little tail
light of the vehicle in front of me), I'll make a few shifts from one side of the road to another, and I find it helps gets my 'full' field of vision back on track, more engaged.

David Wrote:As far as fast enough, I don't remember offhand Bates saying a few times a second (any idea?), but that does sound roughly right. It's always nice to verify things like that, even if Bates did put a lot of time into the research. I don't know, I have a hard time counting. I think faster than 3 or 4 times a second is possible, but that's certainly enough to start with anyway, and a lot better than 1 per second

I probably took that a little out of context. Bates talked about it in his book in the chapter on Shifting and Swinging. He was mainly referring to being able to realize the swing, if shifting was too fast:

Chapt. 15

"Shifting may be done slowly or rapidly, according to the state of the vision. At the beginning the patient will be likely to strain if he shifts too rapidly; and then the point shifted from will not be seen worse, and there will be no swing. As improvement is made, the speed can be increased. It is usually impossible, however, to realize the swing if the shifting is more rapid than two or three times a second."

Shifting can certainly be done a little faster than that, but the swing may not be realized. Not so big a deal with those who have normal sight. They aren't usually aware of the swing anyways, and don't really have to be, when all is working in good order. But for the sake of restoring vision, with Bates it was a vital feedback mechanism, evidence that one was shifting correctly, not just moving the eyes (moving the attention, seeing best where one is looking). I spent an inordinate amount of time on shifting and swinging (probably a year or two), without much benefit. I got very good at being able to swing things, but looking back, it was a manufactured swing, one which I was able to do because I had really good mechanical control over my eyes, and could
flick them with a lot of agility.. at the time I didn't realize that what was really needed was to move my point of attention, and let go of the eyes, from a mechanical standpoint. I found myself straining much less when I just forgot about the swing, and let what happens, happen, swing-wise.

David Wrote:At some point the saccades and microsaccades kind of start meshing together as the distance and frequency of each gets closer, so that makes it hard to count too.

Yes, exactly. The smallest scale of our voluntary saccades overlap the largest scale of involuntary microsaccades, so that even researchers cannot distinguish if it was voluntary, or involuntary... a gray area, where
they just have to discount the data. Our small, voluntary saccades ARE good training and rehearsal for the involuntary system. Assuming one can shift on that scale without straining.

Regards,

Andrew
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#49
minjja, I just wanted to let you know I saw your picture, and actually it's a nice one to use. Very realistic situation. But I'm just delaying because I'm still considering different patterns of looking at things and am not sure what I want to give an example of yet.
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"Half of our funny, heathen lives, we are bent double to gather things we have tossed away." - George Meredith
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#50
David Wrote:minjja, I just wanted to let you know I saw your picture, and actually it's a nice one to use. Very realistic situation. But I'm just delaying because I'm still considering different patterns of looking at things and am not sure what I want to give an example of yet.

OK David I´m patient Wink
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#51
I know this topic is dead, but I have a quick question David. When I try to attempt this, it's very hard for me to go move my eyes down. It frustrates me. My eye movement is not fluid it's not rythmical. That's a better word. Also, I was having effects like a camera. You know when they're kind of zooming in and zoom out? Trying to focus? Also, if u could teach me how to find details. I cannot find the post! Anyway, thanks in advance
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#52
Mandodesi524 Wrote:I know this topic is dead, but I have a quick question David. When I try to attempt this, it's very hard for me to go move my eyes down. It frustrates me. My eye movement is not fluid it's not rythmical. That's a better word. Also, I was having effects like a camera. You know when they're kind of zooming in and zoom out? Trying to focus? Also, if u could teach me how to find details. I cannot find the post! Anyway, thanks in advance

I will assume you can normally turn your eyes down just fine to look at something like you normally do, as long as you aren't concerned about doing any exercise like this. Jonathan Barnes mentioned something in his book Improve Your Eyesight about how you can walk along the street thinking about something and not even think about walking for the longest time. But as soon as you think about the mechanics of walking, what muscle does what, how to move each part of your leg, the whole process goes wrong. Vision is like that too, in the sense that you can't take control of your eyes and try to force them to make smooth movements. The way to effectively fix the way you move your eyes is by being more involved mentally in the process of looking for and seeing details. When you normally look from one thing to another a far distance apart, you do so very rapidly and easily, not in a slow controlled movement. There's no reason to take time with it because you instinctively know how to turn and look at something instantly. That's one thing that I think virtually everyone does right in between staring.

If you notice your focus moving in and out, instead of paying attention to that function of your eyes, keep your attention on what you're seeing and the mental process of looking. That's a crude description without specifics, but it's a guideline to consider.
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"Half of our funny, heathen lives, we are bent double to gather things we have tossed away." - George Meredith
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