English: 1. Put the screen in the center of your face about 15 inches (40 cm) away from you.

2. With your right eye closed, focus on the red circle with your left eye, and slowly move your face closer while still focusing on the circle.

3. At some point, the black square on the right will vanish from your sight. The image of the black square is now hitting the blind spot of your retina and now information about the shape or colour of the black square is being sent to your brain.

4. Notice that, even though the black square has vanished, while you continue to look at the red circle you don’t perceive a blank spot. You perceive a rectangle entirely filled with yellow.

5. If you close your left eye and look at the black square with your right eye, and repeat the process, the red circle should disappear in the blind spot of your other eye.

6. Notice that, while you look at the red square, you perceive the rectangle on the right to be filled up with only yellow circles, with no gaps.