Researchers "planted" fit and unfit looking women around a college gym. Then they timed how long it took for the female student to approach a piece of equipment next to them. Women tended to choose machines next to the unfit woman faster, we are talking about one minutes vs. three minutes.
The researchers hypothesized that the reason participants were more reluctant to work out next to a fit peer was more about judging ourselves and how we looked in comparison.
I think I need some video footage to actually believe these results. My own personal experience is that if there is a machine open I am going to use it. I will not use it if there is someone really smelly next to me, but that is about the only reason.
I always go into competition with the person next to me, regardless of their body composition. It is just human nature. What do you think? Do you find yourself preferring to work out next to one type of person?