Tired eyes
Color in a gray photo
Start the timer and stare at the black dot until the photo turns gray. What colors do you see?
For a few seconds the gray photo is in color: a blue sky and red-brown temples. Move your eyes and the colors are gone.
Why? The colors you stared at tire your eye’s cells for them, so on the gray photo you see their opposites, which are the photo’s real colors. Your brain paints them into the shapes it sees. John Sadowski made this kind of picture famous.
Picture: Nirajan pant, colors changed by Science Playground, CC BY-SA 4.0 · Wikipedia(opens in a new tab)