Persistence of Vision + the Phi Phenomenon

NOTE THE demonstration of the phi phenomenon on the right. This is the illusion of movement by displacement. In the phi phenomenon, speed is not that important (unlike with persistence of vision).         Note too, in the image on the left, that color consistency does not matter, since the colors of the two balls are now different. What matters is the psychological illusion of continuity (hence, continuous motion).
    This is related to the need for visual simplicity, showed by Gestalt psychologists; that is, a single moving ball is more simple than two stationary (still) balls. You see this every night when you go out and see neon lights moving in a straight line. Of course, they're not moving at all: one is blinking at a time in succession.
    Together with persistence of vision, this helps produce the illusion of motion in motion pictures, which, as you know, don't move at all.
    (By the way, I'm aware that what I call the phi phenomenon is more correctly called "beta motion." But almost all textbooks use the term "phi phenomenon" and that's the term we'll use. It's easier than having all the film textbooks removed from the market. :-)
    The next image, on the left, is an example of an early illusion toy called the thaumotrope. The toy is based on the persistence of vision. An image one one side is flashed with an image on the other side so rapidly that the two images blend, as you can see (still images of both sides are attached to this email).
    These two principles, together with stop-motion photography, produce the animated cartoon. You can see a demonstration on the right.
    Many of us have been surrounded by moving images for so long, we have to rediscover the miracle involved. Moreover, the basic illusion of motion pictures (the fact that there is only an illusion of motion) is the basis of all other illusions of motion pictures (narrative continuity, eyeline matches, parallel editing, and so much more). An appreciation of the illusion is the basis of an appreciation of motion pictures themselves.

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