O'Connor JJM & Feinberg DR. The influence of facial masculinity and voice pitch on jealousy and perceptions of intrasexual rivalry. Personality and Individual DIfferences. 52(3): 369-373.

The assessment of same-sex individuals as intrasexual competitors may depend in part on the perceived mate value of potential rivals. Men's and women's preferences for vocal and facial masculinity suggest that feminine women and masculine men may be perceived as more threatening intrasexual competitors. We tested the influence of men's and women's vocal and facial masculinity on preferences for who should accompany romantic partners on a weekend trip and on jealousy in response to imagined flirting. We found that men and women preferred their partners to be accompanied by people who had less masculine/feminine voices, and were more jealous in response to people who had relatively more masculine/feminine voices. Women, but not men, rated faces with exaggerated sex-typical characteristics as undesirable travel companions for their romantic partners and reported more jealousy in response to imagined flirting from such faces. We also found that participants who rated masculine male and feminine female stimuli as more attractive also perceived such stimuli as greater intrasexual threats, demonstrating individual differences in competition-related social perceptions. Our findings indicate that perceptions related to intrasexual competition are related to cues to underlying mate quality, which may aid in effective mate guarding.