A three-by-three grid of blue-ish dots is shown. The background is muted gray-ish blue. Oddly, the dot on which you concentrate will appear a darker purple. And this color change will follow you! If you look at a different dot, then the new dot will turn purple, with your original dot returning to its original color.

Decidedly weird.

#opticalillusion #illusionfun #illusions #purplemath