Five autostereograms create the visual illusion of a three-dimensional (3D) scene from a two-dimensional image in the human brain. In order to perceive 3D shapes in these autostereograms, the brain must overcome the normally automatic coordination between focusing and vergence.
INSTRUCTIONS TO VIEW STEREOGRAMS:
1. Hold the picture up to your nose and relax your focus.
2. Your eyes should be focused afar. Do not try to focus on the picture.
3. Slowly pull the picture away from your face, while still maintaining a distant focus.
4. Allow the picture to come into focus.
5. Repeat 1-4 until this works.