I stumbled upon this link this morning. It's an interesting test about real and fake smiles. You get to see 20 short clips of people smiling into the camera. Then you have to tell if it's a real or a fake smile. You can watch each clip only once.
If you're animating characters it's always important to think about 'fake' or 'real'. You have to be able to animate both. But what makes the difference between those two smiles...? Go do the test ;)
Spot The Fake Smile
And don't forget to tell me your score. ^^v
I got 18 out of 20
I guessed those wrong...