Most notably, say the researchers, the physics students in the survey showed the largest bias toward female physics teachers. In biology and chemistry, male students tended to underrate their female teachers, but female students did not. In physics, both male and female students tended to underrate their female teachers.
I don't have access to this publication since my institution doesn't subscribe to it, so I could not tell you more about the content than what's being reported here. If you do have access to it and have read it, I would like to hear a bit more on the content, especially if they have made any proposal on the possible reason for such a bias.
My initial inclination is that in physics, the predominant "role model" of a physicist is typically a "nerdy man" with ruffled hair, a lab coat, and may be horribly absent-minded. So a female physics teacher doesn't fit into what these students probably think a physicist should look like and so, give them less credibility.
We need not only more female physicists to be pushed to the limelight (I guess that's what Lisa Randall is doing), but also more studly and handsome male physicists to dispel the nerdy myth! :)