Northwestern Panel Interview? I went Sep '03.
Definitely was a refreshing change of pace from one-on-one interviews. My interview was with two guys from the West Coast and we were interviewed by two physicians and a medical student.
One physician was clinical, the other was research, and the medical student (I believe) was a M4.
The interview sounds like it's rough, but as long as you keep relaxed and let other people have a chance, it's no big deal. This isn't your time to grandstand. I think the panel's also looking to see how well you listen to the other two interviewees. Questions were pretty random, and the committee 'sniped' us with them (i.e., they would call us out randomly and ask us a different question). The Q's ranged from 'If I walked into your room, what would I find in the CD player, on the coffee table, and in your refrigerator?' to 'Name a current conflict in medicine that is important to you, and what your suggested solution is' and even some questions about the ethics of a Starbucks tax. The good thing about answering questions one at a time is it lets you have a chance to recuperate, and you don't always feel like the spotlight's on you.
The cooperative section is just that - you need to show you can work spontaneously with your group. We needed to come up with a list of 'professional' traits doctors should have, and defend each. The ranking was important. We pretty much came to consensus in front of them and then took turns explaining each point.
I had imagined sitting down at a desk in a large lecture room with three (or more!) interviewers glowering down at our little table, but it took place in a small seminar room with comfortable seats and good lighting. No stress, if you don't let the description psyche you out, like it almost did me.
My advice is to come into Chicago early and wander around the GC, the park, etc. Ride the ferris wheel for the sake of having done it, and just relax. The committee is trying to get to know you, not trying to shoot you down.
But, yes, I do agree - if you totally can't mesh with a new group of people, or you feel the need to stomp over your group members in order to puff yourself up, I think the committee will take that as a red flag. So, don't do it.
Hope that helps! Good luck!
04DukeBio