A Psychologist Explains Why Infidelity Is Contagious

Why do some people gravitate towards short-term pleasures rather than long-term relationships?

By Mark Travers, Ph.D. | September 13, 2022

A new study published in the Archives of Sexual Behavior shows that environments that are rife with infidelity reduce the motivation to protect the existing bond between two partners, making them vulnerable to the possibility of considering alternative partners.

I recently spoke to Gurit E. Birnbaum, a faculty member of the Baruch Ivcher School of Psychology in Israel and lead author of the paper to understand how exposure to environments that foster infidelity cause people to look for alternative partners. Here's a summary of our conversation.

What are the practical takeaways from your research for someone who is prone to engage in infidelity rather than maintaining satisfying long-term relationships?

People should be more aware of the power of situations and the impact they may have on decision-making in the intimate sphere.

Couples in monogamous relationships who live in an environment in which infidelity is acceptable and are prone to engage in affairs (because of certain relationship and personality characteristics) might be offered counseling that encourages refocusing attention on one's primary partner and has proven useful in intensifying sexual desire and the emotional bond between partners (motivating responsiveness and efforts to make the partner feel special, for example).

Enhancing the emotional connection between partners and the desire they experience for each other may render them less susceptible to being affected by threats to their bond, which arise both within and outside their relationship.

What inspired you to investigate the topic of infidelity?

I'm fascinated by how people in monogamous relationships reconcile their conflicting needs for security and separateness. The need for security that such relationships provide may clash with the sense of uncertainty and novelty that fuels desire and is typical of interactions with new partners.

Consequently, people often face a conflict between temptations that lurk outside the relationship and the intent to maintain sexual exclusivity within the current relationship. Those who are committed to their current partner deal with this conflict by using relationship-protective strategies, such as ignoring suitors or perceiving them as less attractive than they are.

These strategies, however, are not always effective, as the high infidelity rates will testify. In this study, we sought to investigate what makes people less resistant to the temptation of alternative partners.

Are there any personality traits that might be associated with infidelity?

Yes, past research has shown that several personality characteristics, such as neuroticism, narcissism, and attachment insecurities, make people more prone to engaging in extradyadic affairs, possibly for different reasons (having a sense of entitlement vs. relieving separation anxiety by securing alternative partners, for example).

Could you briefly describe the methodology of your study?

In the present three studies, we explored 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.

  1. In the first study, we exposed participants to research findings that indicated either high or low prevalence of infidelity. The participants then described in writing the first sexual fantasy that came to their mind. Independent judges read these fantasies and rated the levels of desire experienced in them towards both the current and alternative partners.
  2. In the second study, we explored whether the predicted effect of exposure to norms of infidelity on desire for alternative partners would be observed using a different, more objective measure of desire for alternatives.

In addition, we wished to show that this effect could be attributed to exposure to other people's infidelity 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 read, for example, 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 read, for example, 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 examined 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 were some of the key findings of your study?

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.

You mention that there are certain circumstances that make people gravitate towards attractive alternatives. Could you expand on 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.

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 temptations in a way that promotes infidelity.

More generally, exposure to other people's unethical behavior may change how people perceive the social norms surrounding this behavior (what is commonly done or acceptable in a society). Perceptions of high norms of dishonesty enable people to justify misbehaviors they are about to commit as less immoral.

This justification helps them dismiss the dissonance between long-term goals that support moral values and short-term temptations that violate them in a way that increases the chances of engaging in unethical behavior while keeping a clear conscience.

Did you find any gender differences or other demographic differences?

We found that compared to women, men were less committed to their current relationship as well as expressed in their sexual fantasies a greater desire for both the current and alternative partners. The latter finding is consistent with past research showing that men have a higher sex drive overall than women.

But men and women did not differ in the extent to which they experienced interest in alternative partners following exposure to norms of infidelity. That means that perceiving infidelity as common liberates both men and women from the shackles of their morality, unleashing their desires for alternative partners to the same extent.

Do you have plans for follow-up research? Where would you like to see research on infidelity go in the future?

Yes, I have several series of studies (some of them use virtual reality) examining what makes people more resistant to temptation. We investigate strategies that encourage romantically involved individuals to enact relationship-protective responses toward alternative partners and help inoculate them against their allure. I'd be happy to tell you more about these studies when they are published.