There follows the description of several vision exercises which help in seizing bioptical effects. As shown beforehand, some persons spontaneously see these effects, while others require training. Some persons with normal binocular vision perceive only a part or none of the bioptical combinations.
On a table M we place two objects (O1) and (O2), for instance two plastic containers. They should not be identical but very similar in shape. In front of them an obstacle (P) made of cardboard is placed, so that only the upper part of those objects is visible from a distance of 2…4 meters. The person who undergoes the vision test should sit at the distance of 2…4 meters and close his or her eyes, while a screen E is placed in front of one of the eyes. Another person displaces one of the objects, for instance (O1), to a farther position. The tested person opens both eyes and sees objects O1 and O2 with one only eye.
When screen E is removed, the person should notice the modified position of object O1, hence notice the difference between vision with one eye and the binocular vision. The exercise is repeated for different positions of object (O1). If no difference is perceived, the person has no 3-D vision.
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