Notice: An illusion is a distortion of the senses, revealing how the brain normally organizes and interprets sensory stimulation. While illusions distort reality, they are generally shared by most people. Illusions may occur with more of the human senses than vision, but visual illusions, optical illusions, are the most well known and understood. The emphasis on visual illusions occurs because vision often dominates the other senses. Some illusions are based on general assumptions the brain makes during perception. These assumptions are made using organizational principles, like Gestalt, an individual's ability of depth perception and motion perception, and perceptual constancy. Other illusions occur because of biological sensory structures within the human body or conditions outside of the body within one’s physical environment.
Trick of the Day: The moon when close to the horizon looks bigger than when it's in heart of the sky. That's because when it's close to the horizon, your eyes sees it in comparison to other parts of the horizon, such as trees, mountains and houses, and that's what makes it look bigger. For more tricks and illusions of the day check Tricks of the Day.