Warning: this will hurt your eyes

This is an optical illusion – via Michael Shermer. Don’t stare at it for too long or you might begin to feel dizzy.

This radial sunburst illusion is known as the Asahi figure, and the researchers analyzed people’s eyes while they stared at it, and a number of other similar optical illusions. And just as if they were staring at an actual light source, their pupils contracted.