When it comes to men making decisions on condom use for casual sex, there may not be more to it than meets the eye.

In a survey of 51 heterosexual men between the ages of 19 and 61 published in BMJ Open, researchers found that men’s intentions to use a condom during casual sex varied based on the perceived attractiveness of their potential partner. Specifically, the more attractive a woman seemed to each participant, the lower their intention to use a condom during sex—even if the woman seemed to have a relatively higher risk of having a sexually transmitted infection.

Though the study was small, the finding backs up several others that have found that perceived hotness of a potential sex partner is a key determinant in people’s decisions on whether to have sex and have safe sex (for men and women). And together, the studies suggest that discussions about people’s biases on particularly steamy flings could improve sex education.

For the study, a group of researchers in the UK started with having 51 heterosexual males take a survey about their sex lives, which revealed a wide range of experiences. For instance, the group's average age at first sexual encounter was around 18, with a minimum of 14 and a maximum at 30 years old. The group’s average number of sexual partners was around nine, with one participant reporting zero and another reporting 60.

Next, each participant was shown black-and-white pictures of 20 women’s faces and asked:

Please rate the attractiveness of the following woman

If you were single, how likely would you be to have sex with this woman should the opportunity arise?

If you were single and you were to have sex with this woman, how likely is it that you would use a condom?

How likely is this woman to have an STI?

The higher a woman’s attractiveness rating, the more men were interested in having sex with her and the less interested they were in using a condom. And attractiveness didn't link up with perceived STI risks. In fact, some men were most attracted to women they thought had a high risk of STIs, while others were highly attracted to ladies who they perceived would have a low risk of those infections.

Nevertheless, attractiveness was key to condom use. “Men who are more attracted to ‘riskier’ women are just as disinclined to wear a condom when they have sex with these women as men who are more attracted to ‘safer’ women,” the researchers found.

The findings are particularly significant in light of rising rates of STIs in the US, particularly chlamydia, syphilis, and gonorrhea. Tailored and targeted sex education campaigns that take attractiveness biases into account may help, the researchers suggest.

BMJ Open, 2016. DOI:10.1136/bmjopen-2015-010883 (About DOIs).