What you need:
Paper, sketch pen, ruler
What to do:
1. Draw a small x’ on the right side of your paper.
2. Measure five inches on the left side of that X and in the same line, draw a big dot.
3. Hold the paper in front of you at arm’s length, using your left hand. Close your right eye with the other hand. With your open left eye, look only at the X.
4. While looking constantly at the X. start to gradually move the paper towards you.
5. Repeat these steps with your right eye open and the left one shut.
What happens?
Even though you’re concentrating on the x with your open eye, you can still see the dot. As you move the paper closer to you, there comes a point where the dot completely disappears. But past that point, it reappears! The point at which the dot vanishes is your blind spot! Why?
At the back of your eye, there is a thin, sensitive layer called the retina. This retina is full of cells that receive light colour and other details that your eye sees. Now, the information gathered by these cells has to be sent to the brain so that it may process what the eyes have spotted. This is done via a bundle of nerves that pass through the retina. At the point of passage of these nerves, there are no cells that detect light or colour. This is your blind spot.
When you move the card, there comes a point where the light reflected from the dot hits this spot on your retina and you can’t see it!
The reason we don’t often realize that we have a blind spot is because the brain tends to fill in details with what it thinks should be there. That is why, when the dot disappears, the brain fills in that space with the background colour of your paper, which is what surrounds the dot and the cross.
Picture Credit : Google
