Optical Illusions are images or pictures that we perceive differently than they really are. Put another way, optical illusion occur when our eyes send information to our brains that tricks us into perceiving something that does not match reality. Some optical illusions are physiological. This means that they’re caused by some sort of physical means in the eyes or the brain. Optical Illusion is often classified into categories including the physical and the cognitive or perceptual, and contrasted with optical hallucinations.