Blind Spots

DurkaDurka
#1
http://serendip.brynmawr.edu/bb/blindspot1.html
This is pretty cool, follow the instructions below

Look around
. Do you see a blind spot anywhere? Maybe the blind spot for one eye is at a different place than the blind spot for the other (this is actually true), so you don't notice it because each eye sees what the other doesn't. Close one eye and look around again. Now do you see a blind spot? Hmm. Maybe its just a little TINY blind spot, so small that you (and your brain) just ignore it. Nope, its actually a pretty BIG blind spot, as you'll see if you look at the diagram below and follow the instructions.

Close your left eye and stare at the cross mark in the diagram with your right eye. Off to the right you should be able to see the spot. Don't LOOK at it; just notice that it is there off to the right (if its not, move farther away from the computer screen; you should be able to see the dot if you're a couple of feet away). Now slowly move toward the computer screen. Keep looking at the cross mark while you move. At a particular distance (probably a foot or so), the spot will disappear (it will reappear again if you move even closer). The spot disappears because it falls on the optic nerve head, the hole in the photoreceptor sheet.
So, as you can see, you have a pretty big blind spot, at least as big as the spot in the diagram. What's particularly interesting though is that you don't SEE it. When the spot disappears you still don't SEE a hole. What you see instead is a continuous white field (remember not to LOOK at it; if you do you'll see the spot instead). What you see is something the brain is making up, since the eye isn't actually telling the brain anything at all about that particular part of the picture.
 
hermanntrude
#2
a bit of white screen has to be the most boring hallucenation I ever had.
 
darkbeaver
#3
That is very interesting. My eyes lie to my brain. How come?
 
hermanntrude
#4
Quote: Originally Posted by darkbeaverView Post

That is very interesting. My eyes lie to my brain. How come?

it's a conspiracy

or perhaps your brain can't handle the truth
 
DurkaDurka
#5
Quote: Originally Posted by hermanntrudeView Post

a bit of white screen has to be the most boring hallucenation I ever had.

you better brew your self some chemicals in your lab to make the white space a little more exciting then.
 
karrie
#6
Quote: Originally Posted by darkbeaverView Post

That is very interesting. My eyes lie to my brain. How come?

They lie to your brain because it would presumably be too distracting for us to see an actual blind spot all the time. Imagine constantly trying to look around a 'hole' in your vision. But, as it is, we do tend to compensate for the blindshopts (caused by where the optic nerve leaves your eye), even if we don't do it consciously, by rarely letting our eyes settle on one item for any serious length of time like that.
 
darkbeaver
#7
Quote: Originally Posted by hermanntrudeView Post

it's a conspiracy

or perhaps your brain can't handle the truth

My brain obviously can't handle the truth. It is, in fact, a conspiracy of brain cells to conceal the truth from me. But it lies to me all the time. If I travel by car on a familiar route to carry out an errand at some destination I (we) will frequently not remember the trip, we just sort of arrive in the parking lot. Most of what we assemble mentally on such a trip is drawn from memory of previous trips.
 

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