This really does work! I tested it. Tell me what you think.
DIRECTIONS AND LINK BELOW:
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).
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.
You can repeat this experiment by closing your right eye and staring at the spot with your left eye. Notice that the cross will now disappear at a particular distance.
http://www.umds.ac.uk/physiology/daveb/brainday/blind.htm
Please note that you need to be level with the monitor and don't try to look at the dot, only the + sign.