Wednesday, December 20, 2006
Our Natural Blind Spots
Cover your right eye with your hand. Focus your left eye on the right dot. While your eye is still covered, move your entire head slowly in towards the screen, keeping your left eye focused on the right dot. Partway in, you will notice that the other dot disappears in a field of white.
You can also cause this to happen with the other eye. Cover your left eye with your hand; focus your right eye on the left dot. Move in until the other dot disappears.
This happens because you have two natural blind spots where the optical nerve attaches to the back of each eye. Your brain fills in the white background based on information from the surrounding area so that it doesn't look like there's a hole in your vision.
So we all go through life with two blind spots that we rarely notice - at least until something appears where it should not have been.
Play with your blind spots some more here.