Persistence of vision

Persistence of vision
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This article is about the theory on human vision. For other uses, see Persistence of vision (disambiguation).

In the lilac chaser, we see a moving purple dot (a standard illustration of the phi phenomenon). However, if you stare at the image for long enough the dot appears to erase itself. This is because the dot produces an afterimage which is green (the complimentary colour of the original dot). When the green afterimage combines with a purple dot, a gray dot is produced, exactly the same colour of the background. Now, the existence of after image is presumed to be evidence for the persistence of vision hypothesis, but as you can see here, the afterimage actually interferes with the movement of the dot. Thus the presence of after image cannot be the cause of the movement.
Persistence of vision is the phenomenon of the eye by which an afterimage is thought to persist for approximately one twenty-fifth of a second on the retina.
The myth of persistence of vision is the mistaken belief that human perception of motion (brain centered) is the result of persistence of vision (eye centred). The myth was debunked in 1912 by Wertheimer[1] but persists in many citations in many classic and modern film-theory texts.[2][3][4] A more plausible theory to explain motion perception (at least on a descriptive level) are two distinct perceptual illusions: phi phenomenon and beta movement.
Film academics and theorists generally have not. Some scientists nowadays consider the entire theory a myth.[5]
In contrasting persistence of vision theory with phi phenomena, a critical part of understanding that emerges with these visual perception phenomena is that the eye is not a camera. In other words vision is not as simple as light passing through a lens, since the brain has to make sense of the visual data the eye provides and construct a coherent picture of reality. Joseph Anderson and Barbara Fisher argue that the phi phenomena privileges a more constructionist approach to the cinema (David Bordwell, Noël Carroll, Kirsten Thompson), whereas the persistence of vision privileges a realist approach (Andre Bazin, Christian Metz, Jean-Louis Baudry)[5].
The discovery of persistence of vision is attributed to the Roman poet Lucretius, although he only mentions it in connection with images seen in a dream. [6]. In the modern era, some stroboscopic experiments performed by Peter Mark Roget in 1824 were also cited as the basis for the theory. [7]