Look through your hand

Principle
The experiment is based on binocular fusion, in which the brain combines the images from both eyes to create a single perception. The right eye sees the image through the tube, while the left eye sees the hand and the surroundings next to it. The brain merges these different images into a coherent scene. Instead of a blocked field of vision through the hand, the impression is created as if one could "see through the hand" because the brain integrates the information from both eyes in such a way that the hand becomes virtually "invisible" in order to minimize the disturbance in vision.