*Deconfounding Sex and Sex of Partner in Mate-Preference Research.

Much of the previous research examining sex differences in human mate preferences has relied exclusively on heterosexual participants. Consequently, prior work overlooks a critical limitation: In heterosexual populations, participant sex and partner sex are perfectly confounded. Here, we tease apart this fundamental problem by separately examining ideal preferences for male and female partners across two studies-one using a large bisexual sample (n = 442) and another using a sample of both bisexual and heterosexual participants (n = 380). The results revealed that sex differences in mate preferences were largely driven by the participants' own sex. However, both males and females set higher standards overall for the traits of male partners. These findings suggest that a person's mate-preference psychology is shaped by both one's own sex and the sex of the target being evaluated. More broadly, these results expand our understanding of the proximate psychology underlying human mate preferences.