The idea is to focus on the dot in the centre and then move your head constantly towards and away from the monitor. when you move your head toward the moniter you will get to see the black dots appearing small from the actual size, and when you move your head away from the moniter you will get to see the black dots appers to be much bigger from the actual size of the dots.
This is similar to the Rotating Circle Illusion. This Circle Illusion Continuesly appears to glow, confused person may ask you a question, Is that circle is Glowing?
This is similar to the Rotating Illusion which always keep rotating. In real the image is not Moving at all but while looking up the Illusions closely it look like Moving or Rotating
How many F's are there:
