New study finds infidelity fears drive both affectionate gestures and controlling behaviors

New research has confirmed that having participants imagine their partner cheating on them increases their jealousy. This, in turn, makes them more likely to use strategies intended to retain their partner by either inflicting costs (e.g., inducing jealousy, making threats) or providing benefits (e.g., giving gifts, showing affection). The research was published in Evolutionary Psychology.

Since the early days of human evolution, children have depended on both parents for care. This parental investment was facilitated by the tendency of humans to form monogamous, long-term romantic relationships. While such relationships are rare among sexually reproducing animal species, they are the norm in most human populations.

However, the formation of long-term romantic relationships and the reliance on them introduce unique challenges. One of the most significant challenges is infidelity—that is, a partner engaging in a romantic or intimate relationship with someone else and violating agreed-upon boundaries. To counteract this persistent threat, humans evolved jealousy, a negative emotion characterized by distress in response to a real or perceived threat to a valued relationship.

Study author Steven Arnocky and his colleagues sought to examine whether the perception that one’s partner might engage in infidelity would evoke feelings of jealousy. They also wanted to determine whether jealousy mediates the link between an experimentally induced threat of infidelity and mate retention behaviors. The researchers hypothesized that perceiving a threat of infidelity would lead participants to engage in mate retention behaviors that would persist over the following month.

The study involved 222 participants recruited via MTurk, including 97 women. The average participant age was 33 years, and 75% of participants identified as heterosexual. The researchers compensated them $1 for their time.

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Participants were randomly assigned to one of two groups: the infidelity threat condition or the control condition. Those in the infidelity threat condition watched a one-minute TikTok video of a therapist discussing the prevalence of infidelity in committed relationships. After watching the video, they were asked to imagine that their romantic partner had become interested in someone else, was having sex with them, and was falling in love with that person. This exercise was designed to induce feelings of a perceived infidelity threat.

Participants in the control group watched a one-minute TikTok video featuring a negative food review. Afterward, they were asked to recall a time when they were excited about a meal but then found it disappointing.

Following these tasks, participants completed assessments of state jealousy (e.g., “At this moment, how jealous do you feel in your current romantic relationship?”) and mate retention behaviors using the 38-item Mate Retention Inventory Short Form.

The results showed that imagining a partner’s infidelity increased participants’ jealousy. In turn, participants who felt more jealous reported a higher likelihood of engaging in mate retention behaviors over the following month. These behaviors included both benefit-providing strategies (e.g., giving gifts, showing affection) and cost-inflicting strategies (e.g., inducing jealousy, making threats).

Benefit-providing mate retention behaviors enhance a partner’s satisfaction and commitment through actions such as giving gifts, expressing affection, or offering emotional support. In contrast, cost-inflicting mate retention behaviors aim to deter a partner from leaving by exerting control, inducing jealousy, or making threats—actions that can create emotional and physical distress.

“Participants exposed to an experimental infidelity threat condition reported higher state jealousy scores than those in the control condition. Jealousy, in turn, predicted more intended benefit-provisioning and cost-inflicting mate retention to be performed over the following month. These findings, which extend beyond extant cross-sectional tests of this model, support the perspective that jealousy plays a crucial role in responding to threats to mating relationships by motivating greater mate retention efforts,” the study authors concluded.

The study contributes to the scientific understanding of jealousy’s role in human behavior. However, its findings are limited by the use of MTurk participants, who may not be fully representative of the general population. Additionally, all measures were self-reported, leaving room for reporting bias to affect the results.

The paper, “An Experimental Test of Jealousy’s Evolved Function: Imagined Partner Infidelity Induces Jealousy, Which Predicts Positive Attitude Towards Mate Retention,” was authored by Steven Arnocky, Kayla Kubinec, Megan MacKinnon, and Dwight Mazmanian.