Studies show that students live up to the instructor's expectations, unconsciously trying to prove the expectations correct .
If a professor makes a sexist joke, a female student might well find it so disturbing that she is unable to listen to the rest of the lecture . Suggestive pictures used in lectures on image processing are similarly distracting to the women listeners and convey the message that the lecturer caters to the males only. For example, it is amazing that the ``Lena" pin-up image is still used as an example in courses and published as a test image in journals today 
``Dealing with prejudice can drain a person's energy and motivation. After an oral exam in an honors university physics course, my professor said, `You know, you are a girl, but you are good.' My reaction: why continue in a field where the established scientists will expect incompetence from any woman? It is easier to break into a field where people will judge me first on my merits."
D. P. O'Leary