Thank you both.
I haven't applied yet, so I can't just flat out say that I disagree with you. However, from talking to quite a few UCSF med students, I noticed that none of them majored in humanities, or anything other than some form of science (there's a short video clip on UCSF's website in which students introduce themselves. There was one students who said he majored in Psych). Also, I noticed that this theme - everything went great, and I still wasn't accepted - is quite prevalent. But at the same time, some applicants, often in hindsight, can point to a factor that they think is the "culprit" for their rejection. May it be OOS, a very traditional student, not enough research, feeling that something in the interview didn't go as well as it could have.
I understand that it's a game of margins for those who do get the interview, and possibly even those who are asked to submit a secondary. And that is why I asked specifically this applicant - who has the same major as I do, and did research that, it seems to me, is unrelated directly to medicine or neuroscience, but is more focused on a behavioral aspect of life. considering the similarities in our educational backgrounds, I was wondering if I could benefit from this applicant's experience.
As for getting interviews at other top schools and being rejected, it could be because a person is from one coast vs. another. It is my impression that schools often will not accept students after an interview if they doubt that the applicant will move from one coast to another to attend their school. This, however, doesn't seem to be the case with RoseHelene, as UCSF was her top choice.
Perhaps I'm a bit too anal about this process at my current stage, but considering my life situation (live in bay area with wife + newborn with bilateral club-foot that is treated in the area, mortgage, family, AKA support network, in the east bay & SF), being accepted elsewhere but not in UCSF will involve very, very dramatic life changes, that I very strongly prefer to avoid.
Thanks again for the feedback, and I will go back to following your application process from the sidelines as I did up until now. Good luck to you!