Motion perception is the way in which the human mind processes information regarding the movement of objects around it. It also includes the idea of processing the motion of the human body through its surroundings. In addition to allowing the mind to perceive which object is moving through which space, motion perception is also crucial in determining the distance between objects and their sizes.
The relationship between how the brain interprets movement around it and how the world is actually moving is the study of motion perception. Components of motion perception are the human body, mind and the visual systems that receive the information. Most individuals process the information they see without thinking about it. The human mind can instantly understand what in the environment is stationary, what is moving, and at what rate respective to each other those moving items are traveling.
When an individual is standing still and sees a dog getting closer, he or she instinctively knows that the dog is in motion, covering the ground between and moving nearer. Similarly, if the individual is walking with the dog beside him or her, and the dog is remaining stationary in its position respective to the person, the brain understands that the dog is also moving at the same rate of speed as the person. However, when an individual is walking down the street and sees the trees along the sidewalk growing larger, getting closer and finally disappearing from the line of sight, it is understood that those trees are stationary and their relative positions are changed by the movement of the person.
Motion perception also refers to the human brain's ability to interpret motion when there is none present. This can be most visibly demonstrated with the example of watching a movie projected onto a screen through a film reel. The film reel itself is made up of hundreds of individual pictures in which there is no movement. However, when they are projected onto the screen at a high rate of speed, the motion perception abilities of the brain translates the single images the eyes see as having fluid movement.
All components of vision work together in order to allow the human mind to put together an accurate picture of what is going on in the nearby environment. Peripheral vision, or the ability to see something out of the corner of the eye, is poor at detecting details but excellent at seeing motion. Individuals who cannot perceive motion have a very rare condition called akinetopsia.