Have you ever seen an illusion and immediately gotten a headache? If so, then you’re a weakling.

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. Illusions have a long history, going as far back as the ancient Greeks.

In 350 BC, Aristotle wrote that “our senses can be trusted but they can be easily fooled”. He noticed that if you watch a waterfall and shift your gaze to static rocks, the rocks appear to move in the opposite direction of the flow of water, an effect we now call “motion aftereffect” or the waterfall illusion. Tracking the flow of the water seems to “wear out” certain neurons in the brain as they adapt to the motion. When you then shift your gaze to the rocks, other competing neurons overcompensate, causing the illusion of movement in the other direction.

In the 19th century, studying illusions had a real boom because of the increase in scientists studying perception. A school of these scientists created simple illusions that showed how the brain perceives patterns, shapes and colors. This allowed us to understand more greatly that our eyes can play tricks on us.