A study about preference for making relatively vs. absolute more money?
I've found Neighbors as Negatives: Relative Earnings and Well-Being by E.F.P. Luttmer (2005), although I'm not sure it's the right one. I've heard about your study as well, but I thought it was older than 2005. You can read the study I linked and look up the references. There are quite a lot that touch the same subject.