The journal College Teaching found that students who were convinced they are right are more likely to perceive bias in their professors, regardless of where the students fall on the political spectrum. http://www.informaworld.com/smpp/content~db=all?content=10.1080/87567555.2010.511312 It appears that some students who have never been exposed to someone playing Devil's Advocate see the tactic as an attack, as opposed to an attempt to think through and validate one's position, as well as an opportunity to examine one's reasoning for weak points. Students who were more flexible and less rigid in their thinking and viewpoints perceived no bias in the same situations. Interesting, no? I'm always fascinated when someone refuses to even consider alternate viewpoints, and when asking questions about their viewpoint is viewed as an attack, that can make discussions a difficult thing. Your thoughts?