Throughout the years, people have been fascinated with optical illusions. These mesmerizing pictures can be traced back as far as Aristotle, who is documented as the first to notice what neuroscientists today call the motion aftereffect illusion. He noticed that after looking at a moving stream attentively for some time, if he looked at static rocks beside it, they appeared to be floating upstream.
What exactly is an optical illusion? The definition from Optics4kids.com reads: “Optical Illusions can use color, light and patterns to create images that can be deceptive or misleading to our brains. The information gathered by the eye is processed by the brain, creating a perception that in reality, does not match the true image. Perception refers to the interpretation of what we take in through our eyes. Optical illusions occur because our brain is trying to interpret what we see and make sense of the world around us. Optical illusions simply trick our brains into seeing things which may or may not be real."
A simple picture that can trick our brains into seeing things that may or may not be real seems like science fiction rather than science fact, but it is indeed scientific fact. The different parts of the eye work together as a team, taking in images and sending that information to the brain. The brain is inclined to put images we see into familiar forms or patterns. This comes from life experience and knowledge of the world around us. For example, the brain identifies the wheel of a car as being round. If the wheel does not look round from a different angle or perspective the brain will still interpret the wheel as round. Seeing the wheel as round is the information that the brain has been given over and over, and so that is the perception it uses when the angle or perspective is different.
Apryl L. Peroney is education coordinator, Carnegie Science Center.