Thanks for the advice!
I just had a few other questions: Did the student interviewer read your application before interviewing with you? Was it mostly to see if you fit well with them? or just an opportunity to get to know the school? Are there any qualities Pitt is specifically looking for in candidates?
In general, I think that student interviews are very difficult to do well. Possible, but difficult. I put a lot of advice about interviewing on my blog:
http://harvardmedgirl.blogspot.com/2009/06/practice-interview-questions.html
Interviewing with a student is tricky, because it is functionally equivalent to trying to impress yourself. As I mentioned, my student interviewer was practically as new to Pitt as I was. So here you are, sitting down with somebody who went through the hell of AMCAS and interviewing just a few months ago. Can they really attests to what qualities would make you a promising physician? Why would they know more about it than you? Because of two months they spent in medical school learning biochemistry and anatomy? They are not bearded experts on the subject.
To succeed with a student interviewer, follow these general guidelines:
1. ACT VERY PROFESSIONAL - err on the side of seeming boring. We naturally relax around our young peers. An interview setting is not appropriate for that.
2. TALK ABOUT WORK AND RESEARCH - ask them about their work and their research. Students really like to talk about their work, they enjoy being interviewers. Prepare some questions in advance. For example, "Did you consider doing a combined degree program?" or "What do you think about the five-year medical scientist training program? Do you know anybody who is doing it?" Have at least five of those questions ready.
3. BE SOMEWHAT COOL - students will ask you what you do in your spare time. I suppose they could be evaluating how you would fit into their community. You want to sound interesting, but don't say "I party all the time until I'm blue in face". Don't say anything you would not say to your mother-in-law. Interesting activities could be collecting pho recipes, traveling to see ancient images of Cadeceus, or enjoying political posters. Something edgier than gardening, you know?
Anyway, I say so jokingly, but of course it's as serious as your future career. Consider that committee members will read feedback from the students. Imagine what would prompt you to write positively about a person.