Synchronicitously, when I saw your blog I was half way through re-reading “The Myth of Persistence of Vision” (http://tMoPoV.notlong.com) which one of my holography gurus recommended to explain aspects of my experiments in holographic movies AND which yesterday’s firstname.lastname@example.org was discussing in a debate about the Pulfrich effect and last weekend’s Super Bowl in amongst the fact that the recently departed Lux Interior was a well-regarded stereophile. And tMoPoV recommends Norman McLaren's “Pas de Deux”, [it's cheating to only watch the end], which my dance guru recommended I make a holographic movie of in the first place. Small world.
"The Myth of Persistence of Vision" by Joseph and Barbara Anderson is a paper which goes to great lengths to explain that the apparent motion of objects in a film is produced by a processing area in the brain, and has nothing to do with "images persisting on the retina". The latter has been trotted out as a reliable old warhorse for approximately a hundred years, is found in modern film books and film courses, and is quite wrong.
The relevant passage is:
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.
In other words, if persistence of vision were true we would see people moving in real life as if they were a tube shape carved out in the air – like Marcel Duchamp, above, descending a staircase in the same manner as his earlier nude.
The movie mentioned, Pas De Deux, is by Norman McLaren (1967), and is of two ballet dancers filmed against a black background to an accompaniment of pan pipes. Optical effects are used to make previous images of them persist as the new images appear, which produces the effect I'm rather denigrating by calling a "tube shape" and I'm sure it won't help at all to describe it as the type of trail you see moving objects leave when you're tripping. (Allegedly.) If you can take 13 minutes of black and white trippy ballet, it's a beautiful piece of animation. A still does not do it justice, as it's a film specifically about motion, but what the hell, here is one.
The movie is available for watching here.
And Lux Interior, RIP.