If you were to look at a spiral that is rotating clockwise for a couple of minutes and then look at a stationary object (e.g., your hand), you would perceive the illusion that:
A) the stationary object was rotating clockwise
B) the stationary object was rotating counter-clockwise
C) the stationary object had disappeared
D) the stationary object was getting closer to you

Question

Quizplus · Accepted Answer

This phenomenon is known as the motion aftereffect or the waterfall illusion. Staring at a visual pattern moving in one direction for an extended period of time can cause the brain to adapt to that motion and perceive a stationary object as moving in the opposite direction (counter-clockwise in this case).

If You Were to Look at a Spiral That Is