It takes work both at the individual level and it takes work at the group level.

不仅个人需要下功夫,群体也要下功夫。

耶鲁公开课 - 心理学导论课程节选

These results are surprising and disturbing and I said there is work to be done at an individual and group level and this young man challenged me to be more explicit about that.

这些结果都出乎意料，而且让人不安,我说过个人和群体都要下功夫,这位同学要我明确地说怎样下功夫。

耶鲁公开课 - 心理学导论课程节选