Oxytocin administration leads to a preference for masculinized male faces.

Preferences for sexually dimorphic traits in men's faces are consistent with a trade-off between cues to indirect (genetic) and direct (prosociality) benefits, associated perceptually with relative masculinity and femininity respectively. As the neuropeptide oxytocin (OT) has been shown to promote social perception, we hypothesized that temporary OT elevation would result in a preference for masculinity in men's faces, by reducing the apparent social costs of masculine traits. In a double-blind, placebo-controlled study, 96 participants received either 24 IU OT or placebo. They then completed a computer task in which they used the mouse to alter the shape of displayed men's and women's faces, making them look more or less masculine. Participants were instructed to make each face as attractive as possible. OT administration led to a trend for a relative preference for masculinity in men's faces but did not affect preferences for femininity in women's faces, and this effect occurred irrespective of the participant's sex. We tentatively speculate that OT may 'mask' negative personality attributions normally associated with masculine male faces. These results may be pointing to the role of personality attribution in attractiveness judgements, and the role of OT in social perception.