Infidelity May Be Contagious, One Study Finds

Researchers say knowing other people are unfaithful can make you unfaithful, too.
Relationships psychology science cheating infidelity marriage partner
Are you the company you keep? Photo: Priscilla Du Preez, Unsplash

Many things can lead to infidelity—a lapse in judgment, one too many drinks, a long time coming. But researchers from one study say that it could be something that rubs off on you. 

In a study published in the journal Archives of Sexual Behavior in August, researchers found that exposure to others’ infidelity predisposed people to be unfaithful in their own romantic relationships.


The thinking is as follows: Learning about the supposed prevalence of infidelity might decrease a person’s commitment to their own relationship and increase their desire for an alternate partner. 

“In our latest research, we focused on the circumstances under which people are less likely to use [strategies that help them avoid the temptation to cheat]. 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,” wrote Gurit Birnbaum, one of the authors of the study. 

Birnbaum and the other researchers conducted three different studies on heterosexual monogamous relationships. In all studies, they exposed the participants to others’ cheating behavior and recorded their subsequent reactions while they were thinking of or interacting with others. 

In the first study, undergraduate students who were in committed relationships lasting at least four months watched one of two videos—a video that estimated that infidelity was present in 86 percent of relationships, and a video that estimated that it was present in 11 percent of relationships. The researchers then asked the participants to write about a sexual fantasy. Independent judges evaluated these fantasies for levels of desire towards the current and alternative partners.


The study showed that learning that the prevalence of infidelity was either high or low through the videos did not affect the participants’ desire for their current or alternative partners.

But the subsequent studies returned different results.

In the second study, involving undergraduate students who were in committed relationships lasting at least 12 months, the researchers exposed participants to either an act of infidelity or another act of “unethical behavior in general,” like cheating on schoolwork.

For example, participants in the infidelity condition read:

“I met a gorgeous man during an interview at his workplace. I got the job and started working with him. After a few of [sic] 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.”

While participants in the academic cheating condition read:

“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.”

The participants then viewed pictures of “attractive strangers of the other gender,” and indicated whether they would consider the pictured individuals as prospective partners. The number of people they said they would consider as partners was used as an index of interest in alternative partners. 


Those who read about romantic infidelity responded “yes” to more photos than those who read about academic cheating, indicating an interest in more new partners. 

In the third study, the researchers examined not only whether exposure to others’ infidelity would increase the participants’ desire for other partners, but also whether they would exert more effort to see these other partners in the future.

To do so, undergraduate students who were in committed relationships lasting at least four months read the results of either one or two surveys. One estimated that the prevalence of romantic infidelity was 85 percent, while the other estimated that 85 percent was the prevalence of academic cheating. 

The participants then used an instant messaging platform to interact with a research assistant whose photo was an “attractive” member of the opposite sex. The research assistants asked about the participants' hobbies and interests, and at the end of the interview said, “You definitely raised my curiosity! I hope to see you again, and this time face to face.” The participants were then asked to respond to that message as well as rate their interviewer’s sexual desirability and their commitment to their current relationship. Independent judges evaluated the participants’ responses for the efforts the participants said they would make to see their interviewers in person. 

Results showed that participants who were exposed to the romantic infidelity survey and found their interviewer attractive were more likely to send messages to their interviewer expressing a desire to meet again. Participants who were exposed to romantic infidelity also indicated less commitment to their current relationships compared to those exposed to academic cheating. Additionally, the researchers found that men were less committed to their current relationships than women, regardless of whether they were exposed to romantic infidelity or academic cheating. 


The researchers took these results to mean that exposure to the infidelity of others makes people less likely to commit to their current relationships and more likely to seek other partners. 

“Following exposure to others’ infidelity, participants experienced less commitment to their relationship and 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,” wrote Birnbaum.

An individual who says they would seek an alternate partner or shows signs of wanting to see another individual in person is not the same as actually having an affair. But the researchers wrote that environments in which infidelity is common may justify “abandoning long-term priorities of relationship maintenance in favor of pursuing tempting alternatives.” 

The authors reportedly speculate that "exposure to adultery norms may, for example, render long-term goals less prominent and thereby reduce guilt feelings or soften resistance toward infidelity by lessening the motivation to protect the current relationship." They also said, however, that more research is needed to clarify how exactly knowing about or being around others’ infidelity affects people’s own keenness to be unfaithful.

“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,” Birnbaum wrote.

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