Phi phenomenon is the impression of seeing apparent movement. In its simplest form two lights flashed on and off in quick succession, with the right time interval between the flashes will induce people to perceive the light as moving between two points. This illusion is the basis for our perception of movement in films, cartoons and neon light displays. It was discovered at the beginning of the twentieth century by the first Gestalt psychologists, shortly after the film industry was created.
Definition