Tired eyes
Healing grid
Stare at the red dot for 30 seconds without moving your eyes. What happens to the messy squares at the edges?
They seem to line up neatly, as if the grid healed itself. Move your eyes and the mess is back.
Why? Away from where you look your eyes see little detail, so your brain guesses, and its best guess is “more of the same”: the neat grid in the middle. Ryota Kanai found this in 2005; this is our drawing.
Picture: Drawn by Science Playground, after Ryota Kanai