Plateau's spiral

Plateau's spiral 

A white disc on which there is a black band, which winds round and round with each curve outside the previous one and with its origin at the centre of the disc. When the spiral is rotated and fixated at its centre, the circular bands appear to move in and out. When rotation is stopped a motion after-effect (or motion after-image) appears, i.e. the circular bands now seem to move in the opposite direction, and if another stationary object is fixated it will appear to swell or shrink in size in a direction opposite to that seen when fixating the rotating disc. See waterfall after-effect.