Illusory motion

The term illusory motion, also known as motion illusion, is used to define the appearance of movement in a static image. This is an optical illusion in which a static image appears to be moving due to the cognitive effects of interacting color contrasts and shape position.
Another type of motion illusion that causes an optical illusion is when a moving object appears to be moving in a path other than what is perceived by the brain. An example of this can be demonstrated by placing a colored filter over ones eye of the observer, and swinging a ball back and forth in front of them. To the observer the ball appears to be swinging in a circular motion.