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What Makes Someone More Likely to Cheat?

When offered justification, many people take it.

Key points

  • New research explores the circumstances under which people are less likely to use relationship-protective strategies.
  • Exposure to others’ infidelity leads people to experience less commitment to their relationship and greater desire for attractive others.
  • Environments in which infidelity is common may make people feel more comfortable when considering having affairs themselves.
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Source: Gurit Birnbaum's album

Alternative lifestyles, such as swinging, open relationships, and polyamory, have become increasingly acceptable. And yet, most people in Western cultures seek or have a monogamous relationship1. Monogamy's hegemonic dominance does not mean, though, that desires for people other than the current partner cease to exist. The high frequency of sexual fantasies that involve alternative partners will attest to this2.

People who are involved in monogamous relationships commonly resolve the conflict between their desire for alternative partners and the wish to maintain the current relationship by using strategies that help them override the temptation. For example, they may ignore attractive people or perceive them as less desirable than they are3.

In our latest research4, we focused on the circumstances under which people are less likely to use such relationship-protective strategies. We suggest that a peer environment that gives the impression that infidelity is acceptable may be one such circumstance, as knowing that others are having affairs may make people feel more comfortable when considering having affairs themselves.

Three studies on infidelity and social contagion

Research has indeed shown that social norms, which dictate what behaviors are accepted as normal, affect how people resolve a conflict between short-term temptations and long-term goals in other situations, such as alcohol consumption, gambling, and stealing. For example, exposure to cheating behavior of in-group members increased participants’ likelihood of cheating themselves5.

In the present three studies, we wanted to explore whether this social contagion would be observed when it comes to intimate relationships. Specifically, we examined whether exposure to norms of infidelity would decrease the commitment to the current partner while increasing the desire for alternative mates. In all studies, we exposed romantically involved participants to others’ cheating behavior. We then recorded their reactions while they were thinking of or interacting with attractive others.

In the first study, we exposed participants to research findings that indicated either a high or low prevalence of infidelity. The participants then described in writing the first sexual fantasy that came to their minds. Independent judges read these fantasies and rated the levels of desire experienced in them towards both the current and alternative partners.

In the second study, we explored whether the predicted effect of exposure to norms of infidelity on the desire for alternative partners would be observed using a different, more objective measure of the desire for alternatives. In addition, we wished to show that this effect could be attributed to exposure to other people’s infidelity per se rather than to exposure to other people’s unethical behavior in general (e.g., cheating in other domains). For this purpose, participants read confessions that described incidents of cheating on either one’s current partner or academic work.

Participants in the infidelity condition, for example, read the following confession:

“I met a gorgeous man during an interview at his workplace. I got the job and started working with him. After a few weeks, he invited me for dinner. I didn’t think twice and accepted his invitation. We kissed passionately after dinner. It was the best kiss ever! I don’t live with my boyfriend, so he knows nothing about it.”

Participants in the academic cheating condition, for example, read the following confession:

“I'm a student who works around the clock to fund my studies. So sometimes, when I have to write an essay, which I find challenging or time-consuming, I copy it from other students. When things get tough, I may even pay someone to write the essay for me. I just want to graduate and get this degree.”

Then participants evaluated pictures of attractive strangers of the other gender, indicating whether the pictured individual might be a prospective partner. The number of selected partners was used as an index of interest in alternative partners.

In the third study, we explored whether exposure to norms of infidelity would increase not only the desire for alternative partners but also the efforts devoted to seeing them in the future. To do so, participants read the results of a survey indicating a high prevalence of cheating on either current partners or academic work. Then an attractive interviewer of the other gender interviewed them online.

We asked the participants to send a message to the interviewer at the end of the interview. Participants also rated the interviewer’s sexual desirability and their commitment to their current relationship. Independent judges read the messages sent to the interviewers and rated the efforts made by the participants to interact again with them.

What did we find?

Following exposure to others’ infidelity, participants experienced less commitment to their relationship and a greater desire for alternative partners. These findings suggest that environments that foster a greater prevalence of infidelity lessen the motivation to protect the bond with the current partner, possibly setting the stage for unleashing the desire for alternative partners. Such environments may make people more vulnerable to, if not outright “infect” them with, infidelity.

Overall, our research indicates that environments in which infidelity is common may provide the justification for abandoning long-term priorities of relationship maintenance in favor of pursuing tempting alternatives. Of course, environments in which infidelity is prevalent do not necessarily turn people into cheaters. Even so, if someone is already vulnerable to cheating or if opportunities for infidelity arise, these environments can give the extra push needed to resolve the conflict between following moral values and succumbing to short-term temptations in a way that promotes infidelity.

This post also appears here.

Watch my TED Talk on why humans make sex so complicated here.

Facebook image: Dusan Petkovic/Shutterstock


1. Conley, T. D., Ziegler, A., Moors, A. C., Matsick, J. L., & Valentine, B. (2013). A critical examination of popular assumptions about the benefits and outcomes of monogamous relationships. Personality and Social psychology Review, 17, 124-141.

2. Birnbaum, G. E., Kanat-Maymon, Y., Mizrahi, M., Recanati, M., & Orr, R. (2019). What fantasies can do to your relationship: The effects of sexual fantasies on couple interactions. Personality and Social Psychology Bulletin, 45(3), 461-476.

3. Lydon, J., & Karremans, J. C. (2015). Relationship regulation in the face of eye candy: A motivated cognition framework for understanding responses to attractive alternatives. Current Opinion in Psychology, 1, 76-80.

4. Birnbaum, G. E., Zholtack, K., & Ayal, S. (in press). Is infidelity contagious? Online exposure to norms of adultery and its effect on expressions of desire for current and alternative partners. Archives of Sexual Behavior. ResearchGate

5. Gino, F., Ayal, S., & Ariely, D. (2009). Contagion and differentiation in unethical behavior. Psychological Science, 20(3), 393–398.

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