Sit so that the white surface or wall is on your right and have your partner sit a few feet in front of you. Hold the bottom of the mirror with your left hand, and put the mirror edge against your nose so that the reflecting surface of the mirror faces sideways, toward the white surface.
While keeping the mirror edge against your nose, angle the mirror so that your right eye sees just the reflection of the white wall, while your left eye looks forward at your partner's face (see diagram). Move your hand in front of the white surface as if passing a blackboard eraser over the surface. Watch as parts of your friend’s face disappear.
It will help if your friend is sitting very still against a plain, light-colored background. You should also try to keep your own head as still as possible.
If you have trouble seeing your friend’s face disappear, one of your eyes might be stronger than the other. Try the experiment again, but this time switch the eye you use to look at the person and the eye you use to look at the wall. (You and your partner may have to switch places so the white wall is to your left. Position the mirror against your nose so your left eye sees the reflection on the wall and your right eye is looking at your partner. Then wave your left hand.)
Individuals vary greatly in their ability to perceive this effect. You may have to try several times, and a few people may never succeed in observing it. Don’t give up too soon! Give yourself time to see the effect.