Kinetic Depth Effect

In visual perception, the kinetic depth effect is the phenomenon in which the three dimensional structure of an object can be perceived once the object starts moving, even when no other visual cues to depth are available. The psychologists Hans Wallach and Dorothy O'Connell demonstrated in the 1950s that a person's visual system can identify an object's three dimensional structure purely from motion, for example by watching the shadow that a rotating wire shape casts onto a screen. Researchers have offered two explanations for how such three dimensional perception arises: one, associated with Gestalt psychology, holds that the visual system follows built in rules of organization that translate the changing pattern of stimulation on the retina into a three dimensional percept, while the other points to the role of past experience, though this account does not fully explain how prior experience shapes the perception of new images. The kinetic depth effect usually appears together with other depth cues, most notably motion parallax, in which objects farther from an observer appear to move more slowly than closer ones, but it can also appear on its own even when motion parallax is absent.