If he splits his head open and there's blood everywhere, I'm less likely to laugh unless I don't like him or something.

如果他摔个头破血流，我就笑不出，除非我很讨厌这个人。

耶鲁公开课 - 心理学导论课程节选

If you are happy, and work on your happiness, you are contributing indirectly to other people's happiness, just like the baby who laughed last time-- made you laugh.

你快乐并努力争取快乐，就是间直接对他人的快乐作出贡献，就像上次大笑的婴儿，把你们逗笑。

哈佛公开课 - 幸福课课程节选

When you're in a group doing something terribly aggressive and you are not--you don't feel like you're at risk you might laugh and laughter is a signal to other members of your group as a signal of solidarity and what you're doing together.

当你在群体在做具有强烈攻击性的行为时,你不会觉得自己有危险,你会笑,你笑是向其他群体成员传达一个信号,你们团结一致，共同进退。

耶鲁公开课 - 心理学导论课程节选