Thaumatrope

Greek name meaning "wonder turner"

"Although the thaumatrope does not produce animated scenes, it relies on the same persistence of vision principle that other optical toys use to create illusions of motion.  Persistence of vision is the eye's ability to retain an image for roughly 1/20 of a second after the object is gone. In this case, the eye continues to see the two images on either side of the thaumatrope shortly after each has disappeared.  As the thaumatrope spins, the series of quick flashes is interpreted as one continuous image."

(why is the video in fast forward? no idea.)