21 Mind-Boggling Optical Illusions That Will Melt Your Brain

17. How Many Complete Circles?

This totally messes with your eyes. The contrasting black and white squares make it difficult to get a grip on what you are looking at. There are complete circles in this photo, can you count how many?

16. Bug Eyed Celebrities

http://www.dailymotion.com/video/x29ancs_you-won-t-believe-this-optical-illusion_fun Another one that requires you to keep staring at the centre for the illusion to take effect. Keep looking directly at the cross and watch these famous faces change into bug eyed freaks in your peripheral vision. A bit like walking through a hall of mirrors.