想把这句话重新整理一下,改别的句型结构什么的都可以,

sb. conducted an experiment in which the effects of 3 forms of nonverbal behavior（……） on perceptions of power bases（……） were investigated amongst a sample of U.S. students.

如果你是想把括号脱掉,那就改成
sb. conducted an experiment among a sample of U.S. students, trying to figure out the effects of facial expression, visual behavior and body posture have on the perceptions of six forms of power bases, which are reward, coercive, legitimate,referent, expert, and credibility.

Facial expression, visual behavior, and body posture, these 3 forms of nonverbal behavior were investigated among
a sample of U.S. students how they exert effects on perceptions of the six forms of power bases: reward, coercive, legitimate,referent, expert, and credibility.