The Flick in Flicker:
Persistence of Vision and Phi Phenomenon
by Michael Jones

As the most modern of the arts, movies are also the most dependent on science and technology. Born out of the nineteenth century's predilection for machinery, movement, and entertainment, particularly toys employing optical illusions, anticipation of the moving picture had run high since the discovery of photography in the 1830s. Advances in optics and intermittent machine movement made Edison's Kinetograph possible in the 1880s and on December 28, 1895, the movies (as we know them) were born when the Lumière Bros. in Paris charged admission to view their simple documents of everyday life called "actualities."

Their projection system used a "stop/start" intermittent motion and a shutter design which allowed for the regular, interrupted advancement of a projected film strip containing a sequence of tiny stills - much as we still do a century later. Cinema will forever be tied to the technology of the 1800s - as well as its first cousins, the sewing machine and the Gatling gun.

Two phenomena, one optical (persistence of vision) and one psychological (phi), allow us as spectators to complete the illusion of motion pictures. Since an image only strikes the screen intermittently, half the running time of a film we're in total darkness. This flickering image gave rise to the term "flicks" when referring to the movies (and, of course, eventually Flicker). An understanding of these basic principles can enhance our understanding of, and appreciation for, the experimental film - many of which comment on the formal (technical and aesthetic) aspects of the medium.

The Egyptians were acquainted with persistence of vision but a satisfactory explanation waited until 1824, when Peter Mark Roget defined it as the ability of the retina to retain an image of an object for 1/20 to 1/5 second after its removal from our field of vision. (Quickly! Look at a window or other bright field and close your eyes.) As the film projects at 24 frames per second (18 frames per second for Super 8!), persistence of vision or "flicker fusion" prevents us from seeing the lines separating the frames, yet helps us retain briefly the image contained within the frame.

Working with this optical function is a second principle - the "phi phenomenon" or stroboscopic effect. First studied by Max Wertheimer and Hugo Munsterberg between 1912-16, they found that the spectator forms a mental bridge that conceptually completes the action frame-to-frame, allowing us to perceive a series of static images in a continuous movement. Cinema was thus the first art form to rely totally on psycho/optical machine-generated illusions, and as such, may be closer to the circus, the magic and the sideshow, than the realm of the museum and the academic.

(See Parkinson's History of Film, Praeger and Publishers, NY, 1996)