Another cool illusion featured and explained by COGSCIdotNET is the Reverse Spokes Illusion. This particular effect was discovered by Anstis and Rogers, and it works in a way so that grey lines (or “spokes”) separating the pizza into slices, appear to be rotating clockwise. However, on a closer inspection you can clearly see that this is not the case!
What is happening here is that the grayish color-wave traverses the wheel in a counterclockwise direction, and the spokes occasionally get gobbled-up by the pizza slices. This occurs because two of the pizza slices are of the same color as the spokes!