The Lilac Chaser illusion occurs after staring at the cross for 10-20 seconds. In a while, you start seeing green dots chasing the lilac ones. Eventually, you may even notice how all the lilac dots disappear completely. This phenomenon is often referred to as the Pac-Man illusion because it reminds people of the Pac-Man game where a character needs to eat all the dots inside a maze.

The illusion illustrates the aspects of visual perception, when our brains automatically try to smooth out the changes between the images and create a sense of continuity and stability in the world around us.^[1]

There's no definitive explanation yet for how this unusual visual phenomenon works, although studies suggest it occurs not only in our eyes but partially in our brain too.^[2]

Curiously, low contrast or blurry images make the effect stronger.