Spot The Fake Smile...

This experiment is designed to test whether you can spot the difference between a fake smile and a real one. It has 20 questions and should take you 10 minutes. It is based on research by Professor Paul Ekman, a psychologist at the University of California. Each video clip will take approximately 15 seconds.

http://www.bbc.co.uk/science/humanbody/mind/surveys/smiles/

I got 18 out of 20 correct.