In what might change the way you look at women — or men, for that matter — from now on, researchers have found that men go for women with more feminine-looking faces when they're looking for a short-term relationship.

More specifically, the researchers investigated how a man in a relationship perceived women's facial features when they were interested in a fling. The study included 393 men — 207 in a current relationship — who were shown 10 images, each with two photos of the same woman. However, both images were slightly doctored, to portray the woman as more masculine in one, and more feminine in the other.

They were then asked to rate each pair of photos by attractiveness, and to list which ones they would rather date in short- or long-term relationships. They found that the men who were in relationships were more likely to choose feminine female faces for short-term relationships. However, the men who weren't relationships also chose the feminine faces for a short-term hook up.

They also found that these results interacted with a second experiment, which found that the more attractive a man thought he was, the more likely he was to choose feminine faces.

"There are several possible explanations; perhaps some men are inclined to take a long-term partner whilst still attempting to cheat with other, more feminine, women," Anthony Little from the University of Stirling, Scotland, said in a release. "Or maybe once a long-term partner is secured, the potential cost of being discovered may increase a man's choosiness regarding short-term partners relative to unpartnered men."

They also added that the unpartnered men may choose less feminine women because they can increase their short-term mating success by relaxing their standards.  

The findings are similar to studies conducted on women, which found that they preferred men with more masculine features for short-term relationships. In one study, researchers wanted to see if women were more attracted to masculine faces at the height of their menstrual cycle.

They used a much smaller group of women — only 25 — at both high and low fertility days, and asked them to rate photos on a seven-point scale in terms of sexual attractiveness, as if they were rating a potential short-term partner. They also had a separate group of women rate the photos in terms of masculinity and then another group rate them in terms of symmetry.

They found that whether or not the women were menstruating, they were all more likely to choose the more masculine face for short-term relationships.

Sources: 

Little A, Jones B, Feinberg D, et al. Mens Strategic Preferences for Femininity in Female Faces. British Journal of Psychology. 2013. 

Peters M, Simmons L, Rhodes G. Preferences across the Menstrual Cycle for Masculinity and Symmetry in Photographs of Male Faces and Bodies. PLOS One. 2013.