Law of Motion Perception

Motion perception is the process of inferring the speed and direction of objects that move in a visual scene, given some visual input.  The brain creates a sense of motion by assuming that shrinking objects are retreating, and enlarging objects are approaching. 

An example of when our brains perceive motion is when we look at something in 3D. 

 

 

Although you need 3D glasses to get the full effect, this short clip tricks our minds into thinking that the ball is coming closer to us.  This is because the ball is enlarging, and our brains interpret that as the ball approaching us.