Relooking at persistence of vision

From PhalkeFactory

PERSISTENCE OF VISION REVISITED

By Joseph and Barbara Anderson

Introduction

Several years ago we wrote an article entitled "The Myth of Persistence of Vision" which appeared in the Journal of the University Film Association in the fall of 1978 (Anderson and Fisher). In it we offered a considerable volume of evidence that the concept "persistence of vision" was an inaccurate and inadequate explanation of the apparent motion found in a motion picture. At the time we thought the article had laid the matter to rest. We had pronounced persistence of vision dead. And frankly, we expected never again to hear the term, other than in an historical context. Now, more than a decade later, we are drawn once more to the myth of persistence of vision. Why? Because it is still with us. [1] We read a student paper, and we cringe. We attend the lecture of a seasoned film scholar, and we cringe. We cringe not only because they have chosen to perpetuate the notion of persistence of vision, but because they apparently, even at this late date, do not understand its implications. By this time most film scholars seem to have heard of the inadaquacy of the term "persistence of vision." Some have mistakenly substituted the generally misunderstood term "phi phenomenon" as an explanation of filmic motion, and many still cling to the myth. [2] Why are film people so reluctant to let go of this notion? Can it be that no one read our article back in 1978? Surely not. Tim Lyons, editor of the Journal at the time, has told us the article drew more response than any article published during his tenure. No, the problem must be that we were correct when we proposed that "persistence of vision" functions as a unifying myth underpinning film scholarship. The damned thing is a myth! It won't die. It still functions as a myth today. Those engaged in film study cling to persistence of vision because they need it. For film scholars, it is our myth of creation. It answers our central question of origin: Why, when we look at a succession of still images on the film screen or TV set, are we able to see a continuous moving image? We answer, "Persistence of vision." Persistence of vision is the name given to the miracle by which the still silver halide dust of photography is tranformed into palpable, living motion. And just as the story of Adam and Eve explains not only the mechanism by which people originated and reproduced but also specifies the relationship of human beings to God, the myth of creation for the motion picture contains not only the mechanism for the origin of motion, but implies the relationship of the film to the viewer. The viewer implied by the Myth of Persistence of Vision is a passive viewer upon whose sluggish retina images pile up. Dudley Andrew has observed that "persistence of vision...might be associated with a psychoanalytic view of mind, since the passive eye retains the effects of stimuli like a mystic writing pad, a palimpsest, that is like the unconscious." (Andrew 2) Indeed, in the past decade, psychoanalytic-Marxist film scholars have retained the model implied by persistence of vision: theirs is a passive viewer, a spectator who is "positioned," unwittingly "sutured" into the text, and victimized by excess ideology. So why return to the intellectual battlefield of a decade ago and walk among the tumbled stones? Because the relationship between film and viewer is important. Not only must the mechanism of persistence of vision that purported to explain the illusion of motion be replaced by an accurate description of the illusion, but the concept of a passive viewer implied by the myth must be replaced by the viewer implied by an enlightened understanding of the illusion: a meaning-seeking creature who engages the film as actively as he engages the real world about him. To reject the mechanism of persistence of vision is to reject the myth of persistence of vision and the passivity of the viewer it implies. We are therefore compelled to make a second attempt, fifteen years after the first, to demythologize persistence of vision. Let us pose again the basic question: Why, when we look at a succession of still images on the film screen or TV set, are we able to see a continuous moving image? This question is separable into two even more basic questions. Why is the image continuous, and why does it move? In other words, why do the separate frames appear continuous rather than as the intermittent flashes of light which we know them to be? And why do the figures on the screen appear to move about in smooth motion when we know they are in fact still pictures? It is only with hindsight that the problem seems to divide into such clearly separable categories -- the fusing of the flickering light, called flicker fusion in the literature of perceptual psychology, and the appearance of motion which is referred to as apparent motion. Early writers, without the benifit of hindsight, continually confused the two issues. [3] A typical explanation of persistence of vision went something like this: when the human eye is presented with a rapid succession of slightly different images, there is a brief period during which each image, after its disappearance, persists upon the retina, allowing that image to blend smoothly with the next image. Such an explanation might begin to account for a sense of constancy of the light source (flicker fusion), but it is, of course, a totally inadequate explanation of the illusion of motion in the cinema. The proposed fusion or blending of images could produce only the superimposition of successive views, as in Marcel Duchamp's painting "Nude Descending a Staircase" or a frame from Norman McLaren's Pas de Deux. The result would be a piling up of images, or at best a static collage of superimposed still pictures, not an illusion of motion. It is the obvious inadequacy of the explanation, coupled with its recurrence in film literature for almost a century, that arouses one's curiosity about the origins of the notion and the means by which it has been perpetuated.


Early Attempts to Account for Motion in Film


"Persistence of Vision" found its way into film literature in two ways: 1) through a lack of careful scholarship among film writers, and 2) because of a considerable amount of confusion about the nature of apparent motion among early investigators of the phenomenon. In 1926 film historian Terry Ramsaye attributed the discovery of persistence of vision to the English-Swiss physician Peter Mark Roget and reported that Roget presented his finding before the Royal Society in a paper entitled, "Persistence of Vision with regard to Moving Objects" (Ramsaye 10). Thirty years after Ramsaye, another film historian, Arthur Knight, provided the identical citation and recounted the spread of Roget's theory throughout Europe. He listed a number of parlor toys that served to establish the "basic truth of Roget's contention that through some peculiarity of the eye an image is retained for a fraction of a second longer than it actually appears", and went on to assure us that "upon this peculiarity rests the fortune of the entire motion picture industry." (Knight 14) Ramsaye and Knight were apparently referring to a paper presented by Roget on 9 December 1824 entitled "Explanation of an optical deception in the appearance of the spokes of a wheel when seen through vertical apertures" (Roget). In this paper Roget reports that if one views a revolving wheel through a series of vertical slits, "The spokes of the wheel, instead of appearing straight, as they would naturally do if no bars intervened, seem to have a considerable degree of curvature." (Roget 135) While the lateral movement of the wheel was seen, its rotation appeared to cease, the curved spokes seeming to be frozen in one unchanging position. Roget explained that the spokes of the wheel, passing behind the grating, "leave in the eye the trace of a continuous curved line, and the spokes appear to be curved." He likened the phenomenon to the illusion that occurs when a bright object is wheeled rapidly round in a circle, giving rise to the appearance of a line of light throughout the whole circumference: namely, that an impression made by a pencil of rays on the retina, if sufficiently vivid, will remain for a certain time after the cause has ceased. (Roget 135) It is unlikely that any psychologist today would attempt to explain either of these illusions solely in terms of retinal processing, but regardless of the relative accuracy of Roget's conclusions, the point to be made is that the illusion with which Roget was concerned was not an illusion of apparent motion; to the contrary, it is an illusion in which a wheel in real motion appears to stand still, and yet it is on the basis of this explanation that many film scholars accounted for the illusion of motion in a motion picture.

NOTES [1] A sampling of recent texts that perpetuate the notion of persistence of vision are: Steven Bernstein, The Technique of Film Production (Boston: Focal Press, 1988) 3 ("retention of image"). Thomas W. Bohn and Richard L. Stromgren, Light and Shadows, 3rd ed. (Mountain View, CA: Mayfield Publishing Co., 1987) 6. Steven E. Browne, Film Video Terms and Concepts (Boston: Focal Press, 1992) 132. David A. Cook, A History of Narrative Film, 2nd ed. (N.Y.: W.W. Norton & Co., 1990) 1. Louis Gianetti and Scott Eyeman, Flashback: A Brief History of Film (Englewood Cliffs, NJ: Prentice-Hall, 1991)2. Gorham Kindem, The Moving Image (London: Scott Foresman, 1987) 16. Bruce Kawin, How Movies Work (Berkeley: University of California Press, 1992) 48, 550. Lynne S. Gross and Larry W. Ward, Electronic Moviemaking (Belmont, CA: Wadsworth Publishing Co.,1991) 81. Gerald Mast and Marshall Cohen, A Short History of the Movies, 4th ed. (NY: Macmillan, 1986) 9-11, 28. James Monaco, How to Read a Film (N.Y.: Oxford University Press, 1981) 2. Edward Pincus and Steven Ascher, The Filmmaker's Handbook (N.Y.: New American Library, 1984) 2 [2] For an explanation of the "phi phenomenon" see Lloyd Kaufman, Sight and Mind: An Introduction to Visual Perception (NY: Oxford University Press, 1974) 368. [3] Portions of this historical survey were presented in Joseph and Barbara Anderson, "Motion Perception in Motion Pictures," in Teresa DeLauretis and Stephen Heath (eds.), The Cinematic Apparatus (New York: St. Martin's Press, 1980): 76-95. [4] See, for example, Andre Bazin, Qu'est-ce que le cinema? 4 vols. (Paris: Cerf, 1958-62); trans (selection) What is Cinema? 2 vols. (Berkeley: University of California Press, 1967 and 1971); George Sadoul, Histoire generale du cinema (Paris: Denoel, 1948); and George Potonniee, Les Origines du cinematographe (Paris: P. Montel, 1928). [5] Joseph A. Plateau, as quoted in Georges Sadoul, Histoire generale du Cinema, Vol. 1, p. 25: Si plusieurs objets differant entre eux graduellement de forme et de position se montrent successivement devant l'oeil pendant des intervalles tres courts et suffisamment rapproches, les impressions qu'ils produisent sur la retine se lieront entre elles sans se confondre, et l'on croira voir un seul objet changeant graduellement de forme et de position. [6] For discussion of work done by Rudiger von der Heydt and Esther Peterhans on the response of cells in V1 and V2 to illusory contours, see Zeki 76. [7] In the motion picture, a series of rapidly presented, closely spaced images, the duration of each image (34.72 ms with two interruptions of 6.95 ms each), the interval between images or interstimulus interval (6.95 ms), and the spatial displacement from one frame to the next (generally less than 15' of visual arc), fall well within the parameters of short-range apparent motion.