#17: Afterimages

Focus on the middle stripe of this flag for 20-30 seconds. Try not to blink. Then look at a white screen and you should see the flag of the USA in the correct colors. Sometimes it helps to blink once or twice after the background changes. What’s Happening: Your eyes have red, green, and blue sensors that get “tired” if you stare too long. When you look away, they’re out of balance, so you see a color-flipped afterimage for a few seconds until your vision resets.