Question

how can you identify blind spot

Answer 1

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.
What to do:
To find your blind spots, close your left eye and stare at the cross mark on the other side
of this page 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 it’s not, move farther away; you
should be able to see the dot if you’re a couple of feet away. Now slowly move toward
the piece of paper. 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).
Why does this happen:
The spot disappears because it falls on the optic nerve (see picture below).
As you can see, you have a 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.
Vision scientists study our blind spots and what effects they have on our vision. Their
research tells us some interesting things about how best to talk about what the brain
does, like whether the brain actually “fills things in” or instead simply ignores things
about which it has no information, and much, much more.