1. On the left side of a piece of paper, write an “X” .

2. About 5 ½ inches away from the “X,” write an “O.” Make sure they are perfectly horizontal to each other.

3. Cover your left eye. Hold the paper about 1 ½ feet away. Look at the “O” with your right eye. The “X” should disappear. If it doesn’t, move the paper back and forth until it does disappear.

There will be an explanation video! Go check at the Video Archives to see the explained version: Blind Spot Illusion (Explained)

Sources used: 

https://atlanticeyeinstitute.com/blind-spot-is-it-normal/ 

https://www.aao.org/museum-eye-openers/blind-spot 

https://www.britannica.com/science/blind-spot