为什么大部分人不能胳肢自己，是因为它在我们意料之内，没有打闹的侵略性，通常这种引自己笑的念头都会嘎然而止。

The general story of why we can't in general is because there's no surprise, there's no mock aggression, and also there may be a general deadening of self-stimulation.

youdao

那天早上被我们看见时，它们似乎并没有饥肠辘辘，一路上它们脚步轻盈，并且不时停下来打闹玩耍。

On the morning we saw them, they seemed not to be hungry, walking quickly but stopping sometimes to play together.

youdao

习惯了被忽略，习惯了旁边人的嘻戏打闹，习惯了自己的没有资格，习惯了上课时转过头看看天空，这样，其实挺好。

Accustomed to being ignored, accustomed to the next play, accustomed to their not eligible, accustomed to class turned to look at the sky, it is actually quite good.

youdao

The general story of why we can't in general is because there's no surprise, there's no mock aggression, and also there may be a general deadening of self-stimulation.

为什么大部分人不能胳肢自己,是因为它在我们意料之内，没有打闹的侵略性，通常这种引自己笑的念头都会嘎然而止。

耶鲁公开课 - 心理学导论课程节选