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Is seeing believing? (1 Viewer)

Binastro

Well-known member
About two weeks ago I had a migraine aura.
The next day, because of bright sunshine I wore large wrap around polarised dark sunglasses over my distance glasses. These are optically good.

After being out for 15 minutes I removed my sunglasses indoors, and what happened was bleak.
The top 30% of my vision was missing, just black nothingness.
I quickly surmised that what I was seeing was my missing vision due to my eyebrows and forehead.
I assume that my eyes can see 80 degrees off axis in any direction as I can see this sideways.
The missing top vision is completely compensated for by the brain, which sees an overall equal picture.
I thought that my vision would return to normal in ten to fifteen minutes, which is what it slowly did in varying shades of grey. Not fifty, but several.

My optician has never heard or read of this, and says I should repeat it to be scientific, but it is a bit too frightening to try again. Although I am pretty sure what happened.

We definitely do not see what we think we see.

Does the bottom part of our retina have less cells because we don't use this top vision much?

What we see is actually what our brain lets us see.
 
With all due respect to opticians, they're not an MD. I agree with Ed, you need to see someone who knows what he/she is doing. I would start with an opthamologist and possibly a neurologist if this persists or recurs.
 
Yes,
But if you think about it, why don't we see a change in brightness at the line of our eyebrows/forehead in normal vision?
We should see a line or area of different or less brightness, but I don't think that we do. We are not aware of this missing area of vision. I think that our brain fully compensates for this missing area of vision.
There are all sorts of visual disturbance also, some coming with old age.

The only other event I have experienced was maybe 30 years ago, when I never experienced migraine, which came much later.
I was reading a book for a long period against a bright white tablecloth.
I suddenly became totally blind and could see nothing.
I don't usually panic and did not then and just sat there.
After about 15 minutes my vision returned.
I think this was snow blindness.

These two events are the only really troubling ones I have had, except for the migraine auras, which I sometimes get, and are well known. And also some small very brief white lights at peripheral vision.

The optician says that he is frequently asked about visual disturbances and refers people to the eye doctor, but usually nothing is found.
He himself gets visual disturbances, and I suppose other people also experience some.

P.S.
I think that the black top area described was because I don't normally wear such dark large sunglasses, and these fooled my brain when I took them off in normal room lighting. It may be partly because of migraine sensitivity, but the area was exactly where my hand reached my eyebrows when I tested the extent of the blackness.
 
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Actually, I can just detect the line of my eyebrows if I look for it in certain lighting conditions, but normally this goes unnoticed.
The large dark sunglasses probably greatly enhanced this effect.
 
About two weeks ago I had a migraine aura.
The next day, because of bright sunshine I wore large wrap around polarised dark sunglasses over my distance glasses. These are optically good.

After being out for 15 minutes I removed my sunglasses indoors, and what happened was bleak.
The top 30% of my vision was missing, just black nothingness.
I quickly surmised that what I was seeing was my missing vision due to my eyebrows and forehead.
I assume that my eyes can see 80 degrees off axis in any direction as I can see this sideways.
The missing top vision is completely compensated for by the brain, which sees an overall equal picture.
I thought that my vision would return to normal in ten to fifteen minutes, which is what it slowly did in varying shades of grey. Not fifty, but several.

My optician has never heard or read of this, and says I should repeat it to be scientific, but it is a bit too frightening to try again. Although I am pretty sure what happened.

We definitely do not see what we think we see.

Does the bottom part of our retina have less cells because we don't use this top vision much?

What we see is actually what our brain lets us see.

David,

I'm not quite sure that I follow what you're saying, however, these two charts from NASA's Bioastronautics Data Handbook, summarize the typical monocular and binocular visual fields. Viewing forward without rotating the eyes, the brow, cheek, and nose always limit the view, but, of course, this will vary with the individual. If the eyes do rotate (with head fixed) the retinal exposure limits will change accordingly.

I've also attached an article I ran across concerning migraine and visual aura. There is also some discussion of visual illusions and aftereffects involving temporary blindness, etc. Very complicated stuff, but I'm skeptical that it has much relevance to 'normal' vision, with the possible exception of habituation, which makes us cognitively blind to constant visual stimulation having no information content.

What do you think?
Ed
 

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  • Binocular Visual Firld.jpg
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Hi Ed,
I just sent you a PM, but you beat me to it, and answered my questions possibly in post 6.
Thanks very much.
 
I made my up vision about 55 degrees with eyes forward not moving, and 85 degrees outward horizontal.
So in good agreement with the two diagrams above.
I also thought the down vision considerable and see that this is so.

So the question is.
Why don't we always see the upper 50 to 90 degrees, which is shaded by our brow, as darker than the rest of the field?

And.
Do we have fewer light receptors in the lower retina?

P.S.
If our brain corrects for dark areas with no input from our eyes, does this have relevance to our views through binoculars. Or does our brain rapidly adapt and process differently the incoming view provided by our eyes?

P.P.S.
The second diagram of binocular vision view, in post 6, is basically what I saw when I got indoors and removed the wrap around dark polarised sunglasses.
 
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I made my up vision about 55 degrees with eyes forward not moving, and 85 degrees outward horizontal.
So in good agreement with the two diagrams above.
I also thought the down vision considerable and see that this is so.

So the question is.
Why don't we always see the upper 50 to 90 degrees, which is shaded by our brow, as darker than the rest of the field?

And.
Do we have fewer light receptors in the lower retina?

This is basically due to the process of visual Habituation. The brain doesn't waste energy processing stimuli that carry no information content. We become functionally blind to it. By the same token I would imagine that someone with migraine could de-habituate (or re-sensitize) in some way, leading to otherwise unusual perceptions.

Frankly, I'll have to look into the receptor distribution and sensitivity over the retina to respond to the second question, but for starters it's probably safe to regard the distribution as symmetrical. As I recall, the color sensors aren't quite symmetrical. I've got a book on the subject written about 1902, but that's way at the back of the bookrack. :brains:

Ed
 
I made my up vision about 55 degrees with eyes forward not moving, and 85 degrees outward horizontal.
So in good agreement with the two diagrams above.
I also thought the down vision considerable and see that this is so.

So the question is.
Why don't we always see the upper 50 to 90 degrees, which is shaded by our brow, as darker than the rest of the field?

And.
Do we have fewer light receptors in the lower retina?

P.S.
If our brain corrects for dark areas with no input from our eyes, does this have relevance to our views through binoculars. Or does our brain rapidly adapt and process differently the incoming view provided by our eyes?

P.P.S.
The second diagram of binocular vision view, in post 6, is basically what I saw when I got indoors and removed the wrap around dark polarised sunglasses.

Two interesting post scripts. The last supports my speculation that for some reason you de-habituated. There is also a strong suggestion that your sunglasses allowed considerable dark adaptation, leading to massive overstimulation when they were removed.

Regarding the first, my opinion is that the eye-brain uses the same mechanisms with binoculars as without — including habituation processes.

Ed
 
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David,

I'm not quite sure that I follow what you're saying, however, these two charts from NASA's Bioastronautics Data Handbook, summarize the typical monocular and binocular visual fields. Viewing forward without rotating the eyes, the brow, cheek, and nose always limit the view, but, of course, this will vary with the individual. If the eyes do rotate (with head fixed) the retinal exposure limits will change accordingly.

I've also attached an article I ran across concerning migraine and visual aura. There is also some discussion of visual illusions and aftereffects involving temporary blindness, etc. Very complicated stuff, but I'm skeptical that it has much relevance to 'normal' vision, with the possible exception of habituation, which makes us cognitively blind to constant visual stimulation having no information content.

What do you think?
Ed

Bin, Ed,

I think the answer is as plain as the nose on your face! :-O

It's funny (as in strange) that when you trace the origins of many of the world's sayings, that they are actually great fonts of wisdoms, passed down through the ages as story telling and culturally ingrained and normalised through repetition, and the often humorous contexts of usage, thus offering positive psychological reinforcement. They are often used jokingly as 'throw away lines' ...... :brains: 3:)

Up until I read this thread I was happily reading and going about daily functioning without any awareness of the blurry area of vision that is my nose - now, thanks to you b*ggers ;) it's difficult not to notice! :eek!: ..... hopefully, we will have a return to normal programming soon! :smoke:

Btw Bin, I have noticed the two phenomena you mentioned, previously, as well as a myriad other even stranger things! :cat:


Chosun :gh:
 
The brain is designed to notice / act on changes that our senses observe. It's all down to our evolution and fight or flight responses to our surroundings.

You may suddenly feel cold or hear an annoying sound, but you wouldn't go the whole day thinking "the temperature is the same, and there are no annoying noises", your "unconscious" brain measures the constants, and just filters it out. You have enough other things to worry about!

When people are scared, their eyebrows raise to increase the coverage. When angry, they frown to focus on the threat, or protect the eyes, can't remember exactly.

I'm trying to remember this from a very interesting psychology book I read years ago, so may have got it slightly wrong, but pretty sure that was the general idea.
 
Hi Chosun,
Perhaps a nose job would help.

I am glad at least you have experienced the two phenomena I had.
My observation skills seem to be intact and I am not mad, at least not madder than normal.

My optician described visual disturbances of old age that the person only told his doctor son, as he knew the son would not think him mad. They are now named after him.
There can be few people who have such lengthy discussions with the optician/opthalmologists as I do. I think many visual disturbances are just not talked about by patients.

Concerning common sayings.
'As the crow flies'
Do crows fly in straight lines?
 
Bin, Ed,

I think the answer is as plain as the nose on your face! :-O

It's funny (as in strange) that when you trace the origins of many of the world's sayings, that they are actually great fonts of wisdoms, passed down through the ages as story telling and culturally ingrained and normalised through repetition, and the often humorous contexts of usage, thus offering positive psychological reinforcement. They are often used jokingly as 'throw away lines' ...... :brains: 3:)

Up until I read this thread I was happily reading and going about daily functioning without any awareness of the blurry area of vision that is my nose - now, thanks to you b*ggers ;) it's difficult not to notice! :eek!: ..... hopefully, we will have a return to normal programming soon! :smoke:

Btw Bin, I have noticed the two phenomena you mentioned, previously, as well as a myriad other even stranger things! :cat:


Chosun :gh:

Hi Chosun,

Don't be spooked, but it goes further than that. Move your index finger away from your nose while focusing at the wall behind it. You should experience double vision, i.e., see two index fingers rather than one. Because your eyes are diverged (to focus on the wall), the left and right images fall on non-corresponding points of the retinas, so 'visual fusion' does not take place. Normally, these double images are suppressed from consciousness by the brain, although they are always present and constitute a very large proportion of binocular stimulation. It is said that the suppressed double image data are employed by the brain to create spatial depth perception, so they don't go to waste.

Is seeing believing, or is it the other way round? Does this explain why 'blind drunks' have double vision? |!|

Ed
 
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The brain is designed to notice / act on changes that our senses observe. It's all down to our evolution and fight or flight responses to our surroundings.

You may suddenly feel cold or hear an annoying sound, but you wouldn't go the whole day thinking "the temperature is the same, and there are no annoying noises", your "unconscious" brain measures the constants, and just filters it out. You have enough other things to worry about!

When people are scared, their eyebrows raise to increase the coverage. When angry, they frown to focus on the threat, or protect the eyes, can't remember exactly.

I'm trying to remember this from a very interesting psychology book I read years ago, so may have got it slightly wrong, but pretty sure that was the general idea.

Very interesting.
 
Hi Chosun,
Perhaps a nose job would help.

I am glad at least you have experienced the two phenomena I had.
My observation skills seem to be intact and I am not mad, at least not madder than normal.

My optician described visual disturbances of old age that the person only told his doctor son, as he knew the son would not think him mad. They are now named after him.
There can be few people who have such lengthy discussions with the optician/opthalmologists as I do. I think many visual disturbances are just not talked about by patients.

Concerning common sayings.
'As the crow flies'
Do crows fly in straight lines?

Hey Bin :hi: ..... I have a lovely little cute nose! |:d|

I think Peter's comment is spot on, in that we have evolved to notice changes, and unless you are a compulsive liar - pinocchio style (o)< , the nose should be a pretty constant thing ..... and thus that visual information is usually mentally processed out.

I tend to observe nature by listening and feeling the 'vibe' firstly, and then looking for visual movement after that. It is interesting though that if we are focused on one lot of expected changes, that we can easily miss other changes. The first time I ever saw the "Gorilla" experiment, I definitely missed it - I did however get the throw count right! :cat: This is an interesting analysis, update and extension, here: http://www.smithsonianmag.com/scien...roblem-with-inattentional-blindness-17339778/

Even though my programming has largely returned to normal, now doing Ed's finger experiment has me questioning how many fingers are on each hand?? --- I think it's starting to give me concussion! |:S|

If this keeps up I may need to move to Tasmania, or at the very least Lithgow ......

Stone the crows! By crikey they DO travel in straight lines!! :-O ...... they certainly fly in straighter lines than galahs (flammin' or not :) @_@



Chosun :gh:
 
Hi Chosun,

Don't be spooked, but it goes further than that. Move your index finger away from your nose while focusing at the wall behind it. You should experience double vision, i.e., see two index fingers rather than one. Because your eyes are diverged (to focus on the wall), the left and right images fall on non-corresponding points of the retinas, so 'visual fusion' does not take place. Normally, these double images are suppressed from consciousness by the brain, although they are always present and constitute a very large proportion of binocular stimulation. It is said that the suppressed double image data are employed by the brain to create spatial depth perception, so they don't go to waste.

Is seeing believing, or is it the other way round? Does this explain why 'blind drunks' have double vision? |!|

Ed

Hi Ed,

This indeed is rather freaky! |8.| :cat:
It is amazing that holding your forefinger up and moving it away from your nose while focused on a wall gives 2 very clear forefinger images - all the way to the limits of your arm's extension! It gives you a real sense of having two separate and spaced eyes in your head - well obviously, derr! Ah-mayzing how we are normally only 'conscious' of the 'one' unified vision of the world! :-O

What's even more perplexing with this experiment is that when reaching the limit of your arm's extension, and maintaining focus on the wall - change your fingers so that you are now making a 'V' (victory style with forefinger and middle finger) ..... you will now see not 4, but 3! fingers!! :eek!: ...... I think I really do feel a case of concussion coming on ...... |:S| :bounce:


Chosun :gh:
 
I tried it with two fingers and saw four. With three fingers I got six but after I saw two big middle fingers I figured it was a sign to end the experiment! Perception, the grand illusion.

Hi Chosun,

Don't be spooked, but it goes further than that. Move your index finger away from your nose while focusing at the wall behind it. You should experience double vision, i.e., see two index fingers rather than one. Because your eyes are diverged (to focus on the wall), the left and right images fall on non-corresponding points of the retinas, so 'visual fusion' does not take place. Normally, these double images are suppressed from consciousness by the brain, although they are always present and constitute a very large proportion of binocular stimulation. It is said that the suppressed double image data are employed by the brain to create spatial depth perception, so they don't go to waste.

Is seeing believing, or is it the other way round? Does this explain why 'blind drunks' have double vision? |!|

Ed
 
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