He laughed when he did so. I was to learn that green Martians only laugh at the pain or suffering of others.

VOA: special.2010.07.17

He decided to send himself and his students to different places including shopping malls and observe when people laughed and write down what made them laugh.

除了他自己，他还派他的学生,去各种各样的地方，包括购物商场,观察人们在什么时候会笑,并写下让他们笑的原因。

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