Check on the illusion you see them rotating even when they are still.This is called Optical Illusion

Concentrate on the circle you will see one circle coming out and other going in

Which one is the tallest?? You can easily say the third one but it is not true actually they all are of same size

Pronounce the color which is visible to you and not the one which is written.Give it a try i am sure 90% will fail in first try.