Psychologists are taking a closer look at how the trait known as sociosexuality influences romantic relationships. New research suggests that individuals predisposed to casual sex are not necessarily predisposed to becoming cheaters.

“We became interested in this topic because we wanted to understand why some people in romantic relationships are more successful at shielding off potential alternative partners and protect their relationship, whereas others are not so successful and more likely to have an extradyadic sex (cheating),” explained David Rodrigues of the University Institute of Lisbon, the study’s corresponding author.

The study investigated the interaction between relationship commitment and sociosexuality. Individuals with a restricted sociosexuality favor forming extended bonds with a partner, while those with an unrestricted sociosexuality favor casual sex with little emotional entanglements.

Previous research has found that unrestricted individuals are more likely to cheat on their partners in general. The findings from the new study, however, suggest that commitment can override the desire for casual sex among those with an unrestricted sociosexuality.

“We contrasted two theoretical lines: on the one hand, there is a lot of research showing that people more predisposed to have casual sex (i.e., more unrestricted in their sociosexually) are more likely to attend and pursue attractive others,” Rodrigues told PsyPost. “But at the same time there is a lot of evidence that people who are more committed to their relationship are more likely to use pro-relationship mechanisms such as derogation (i.e., not being so attentive to others and considering them as less attractive). We wondered whether romantic relationships were at risk right from the start when (at least) one of the partners have a more unrestricted sociosexuality, or if highly committed individuals were also more likely to derogate an attractive alternative partners even when sociosexually unrestricted.”

The study was published in April issue of the peer-reviewed journal Archives of Sexual Behavior.

An initial survey of 566 Portuguese heterosexual adults found that men and single individuals tend to be more open to casual sex than women and romantically-involved individuals, respectively.

In a follow-up experiment, 168 Portuguese heterosexual adults were shown a picture of an attractive opposite-sex person and asked to rate their attraction. The researchers found that romantically-involved individuals reported less attraction to the person than single individuals. Importantly, this was true regardless of sociosexuality.

“I think our study served to show that we are not solely motivated by biological factors, but there are also important social factors that can influence our decisions and our behavior,” Rodrigues told PsyPost. “Indeed, we found an interaction between sociosexuality and relationship commitment, that both factors are not mutually exclusive, and individuals are not necessarily predisposed to more extradyadic sex. It is possible, nonetheless, that these individuals have a harder time resisting temptation, but our results showed that even individuals more predisposed are able to resist temptation for the good of their relationship.”

The study found also that more committed individuals reported less sexual infidelity even when sociosexually unrestricted.

But Rodrigues admitted the study had some limitations to take note of.

“We think there are some caveats to our research,” he said. “First of all, our sample was mostly comprised of women. Although research has been showing that gender differences are decreasing in regards to sexual behavior, more empirical findings are still needed to understand why this is happening. For instance, one could argue that the lack of gender differences are due to a greater financial independence from women. However, our sample comprised young adults and some of them were probably still studying at the time of their participation.”

“Another important aspect of the sexual norms within the relationship and feelings of jealousy. Whereas individuals in monogamous relationships without previous extradyadic sex encounters should feel jealousy when there is a sign that the partner is attracted to another person, those in non-monogamous relationships might not. However, it would be interesting to understand what happens with those in a monogamous relationships who has prior extradyadic sex.”

“I would like to thank the people who work with me,” Rodrigues added. “Recent research has re-sparked the interest in the field of romantic relationships and how individual and relational factors interact in the course of a romantic relationship. This has several implications, namely for clinical psychologists working with individuals or in couple’s therapy to understand individual differences and how different relationship configurations can help improve relationship quality and increase mental health.”

The study, “Sociosexuality, Commitment, and Sexual Desire for an Attractive Person“, was also co-authored by Diniz Lopes.