We evaluated five competing hypotheses about what predicts romantic interest. Through a half-block quasi-
experimental design, a large sample of young adults (i.e. responders; n = 335) viewed videos of opposite-sex persons
(i.e. targets) talking about th emselves, and responders rated the targetsˈ traits and their romantic interest in the target.
We tested whether similarity, dissimilarity or overall trait levels on mate value, physical attractiveness, life history
strategy and the Big Five personality factors predicted romantic interest at zero acquaintance and whether sex acted
as a moderator. We tested the respondersˈ individual perception of the targetsˈ traits, in addition to the targetsˈ own
self-reported trait levels and a consensus rating of the targets made by the responders. We used polynomial regression
with response surface analysis within multilevel modelling to test support for each of the hypotheses. Results suggest a
large sex difference in trait perception; when women rated men, they agreed in their perception more often than when
men rated women. However, as a predictor of romantic interest, there were no sex differences. Only the responders ˈ
perception of the targetsˈ physical attractiveness predicted romantic interest; specifically, respondersˈ who rated the
targetsˈ physical attractiveness as higher than themselves reported more romantic interest.