Cognitive dissonance or revenge? Student grades and course evaluations

I tested 2 competing theories to explain the connection between students' expected grades and ratings of instructors: cognitive dissonance and revenge. Cognitive dissonance theory holds that students who expect poor grades rate instructors poorly to minimize ego threat whereas the revenge theory holds that students rate instructors poorly in an attempt to punish them. I tested both theories via an experimental manipulation of the perceived ability to punish instructors through course evaluations. Results indicated that student ratings appear unrelated to the ability to punish instructors, thus supporting cognitive dissonance theory. Alternative interpretations of the data suggest further research is warranted.