FOR a century, moving images have been captivating millions around the world. Yet many of the attractions which bring people into cinema theatres and, more recently, which fix their eyes to television screens for hours on end, are only illusions. We say 'movies' but no movement exists in film -- it is produced in the spectator's mind. The mechanics of this illusion is explained today with reference to two optical phenomena: The persistence of vision, described theoretically by Peter Mark Roget in 1824, and the so-called phi-phenomenon, also known as 'stroboscopic effect,' discovered by the gestalt psychologist Max Wertheimer.(1)
These two effects permit the human brain to perceive a series of related static images (more precisely, motion phases) as a continuous motion. It is this illusion that permits the existence of moving pictures and, more recently, television. Unlike the motion pictures, which need only the illusion of motion, the electronic images of television and video create both the illusion of motion and image. These illusions are the sine qua non prerequisite of the audiovisual media. Without them, they would not exist. Yet they are not the only illusions which the film and television media produce.
There is also the illusion of depth (or the third dimension).(2) Both the celluloid film and the electronic image are by definition two-dimensional; they are projected and observed on a two-dimensional surface. Despite this, film (and television) audiences have the perception of depth -- or rather illusion of depth. The intensity of this illusion varies according to the technology and technique applied by the filmmaker. Since the early years of motion pictures, filmmakers have been aware of this phenomenon which they control through a variety of techniques. For example, the introduction on a massive scale of the long take technique (also called synthetic editing) through Orson Welles' Citizen Kane(3) brought about an increased illusion of depth. This technique has become one of the fundamental stylistic characteristics of the post-World-War-II cinema world-wide.(4)
The illusion of motion and depth in motion pictures, (including the illusion of image in tele-media) are fundamental factors in film and television's intrinsic disposition to produce in the viewer an intense illusion of the real world. The affinity between the projected image and the surface reality creates a strong persuasive pressure on the audience who easily accepts the film image as the image of reality.(5) This effect has been defined by the German film historian and theoretician Siegfried Kracauer: "Struck by the reality character of the [resultant] images, the spectator cannot help reacting to them as he would to the material aspects of nature in the raw which these photographic images reproduce."(6) Paradoxically, this "reality character" of the film image may have little to do with the truth.
There are further reasons why the film audience tends to submit easily to the power of the cinematic illusion; one of them is the very nature of film viewing. In the cinema a person watches the screen in relative isolation -- cut off from the outside world by the darkness of the auditorium and seating arrangement. This creates a distinctive atmosphere which the German psychologist Hugo Mauerhofer calls the "cinema situation."(7) The "cinema situation" intensifies the hypnotic power of the film image.
The intensity of the film-viewing experience can be illustrated by the fact that screen images may produce strong physiological reactions by the viewer, including increase of heartbeat rate, nausea, and vertigo. It is common knowledge that already during the first public film projection by the brothers Lumière in 1895, some front-row viewers panicked at the sight of the approaching locomotive in the Arrival of the Train. Extreme audience reactions (nausea) have been reported in connection with some horror films such as William Friedkin's The Exorcist (1973). Nausea and vertigo have also been reported by audiences viewing images of vigorous motion (via aircraft, boat, rollercoaster, etc.), particularly those produced by large-screen and experimental projection systems such as Omnimax and Circorama; most of these systems stress the illusion of three-dimensionality. The extreme psychological effects of projected images provided the inspiration for the writer Anthony Burgess and director Stanley Kubrick who portrayed them through the "Ludovico Treatment" in their 1971 film Clockwork Orange.