"The I" synoptic viewer
In 1907 a Polish optical scientist named Moritz von Rohr unveiled a strange device named the Synopter, which he claimed could make two-dimensional images appear 3D.
"The I" ensures that both eyes see an image or computer screen from exactly the same perspective. With none of the depth cues associated with binocular disparity, the brain assumes it must be viewing a distant 3D object instead of looking at a 2D image. As a result, the image is perceived as if it were a window the viewer is looking through, and details in the image are interpreted as objects scattered across a landscape.
The perceptual trick, called synoptic vision, is apparent on any nearby two-dimensional image, but is especially marked where other depth cues exist. For instance, the brain will naturally assume an animal in the 2D image is in the foreground if it is large, and far away if it is small.
Read the paper in the New Scientist. here.