13. 如果一個人一半的面部表情比另一半明顯，那么這可能不是真實的情緒

The vast majority of facial displays of emotion are bilateral - that is, they show up on both sides of the face equally. Next time you tell a joke, look to see if her smile is symmetrical when she laughs.
大部分表達情緒的面部表情都是對稱的，也就是說，臉部兩側的表情是對等的。下次你再講笑話時，看看對方的笑容是否是對稱的。