Study: Many of Us Can Spot a Cheater Within 5 Minutes

Can we tell if someone is unfaithful to a partner just by watching the couple communicate with each other? A new study suggests that we may in fact be able to pick up

clues of infidelity by watching couples interact for only a few minutes. In the first study, 51 undergraduate students, all of whom were in relationships, independently completed questionnaires about their own infidelity. When completing this questionnaire, they were asked to think about the person, other than their current partner, they were most attracted to. To ease participants into privately admitting to infidelity, researchers asked them questions that gradually indicated higher levels of unfaithfulness, starting with relatively innocuous questions assessing the mutual attraction between the participant and the attractive alternative partner.5 Two key questions asked participants to rate their level of emotional infidelity (“How emotionally intimate were you with this person?”) and sexual infidelity (“How physically intimate were you with this person?”).

Each participant then interacted with their partner in a task where one wore a blindfold while the other gave instructions, telling the blindfolded person how to draw something. These three-to-five minute interactions were videotaped for later coding.

Could outside observers spot the cheaters just by watching these videos?

To test the accuracy of observers, six coders watched each video and rated how likely they felt the participant was to engage in various unfaithful behaviors—“How likely is it that this person has shown interest in an alternative to his/her partner?”; “How likely is it that the person flirted or made other advances on someone other than the partner?"; and, “How likely do you think it is that this person has had sexual intercourse with someone other than his/her partner?" Results showed a moderate but significant correlation between the coders’ ratings and the participants’ own indications of unfaithful behavior. Additional analyses ruled out the possibility that the results were due to the cheater’s gender or level of dominance.

We are actually surprisingly good at determining others’ personality from just a “thin slice” of behavior. In one study, students who watched silent, nine-second clips of professors lecturing were able to predict, with some accuracy, their actual students’ evaluations of their teaching.1 A brief two-second glance at someone’s photo was enough for people to successfully determine if they had a violent past.2 Dozens of other studies have confirmed the surprising accuracy of our snap judgments.

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Researchers have suggested that our ability to make these somewhat accurate judgments quickly is automatic and adaptive.3 One instance of the adaptive value of making accurate snap judgments is in detecting infidelity.4 If you want to make sure your mate is not cheating, it helps to be able to spot a cheater.

From an evolutionary perspective, those who are adept at detecting cheaters would be more successful in reproduction, as an inability to detect infidelity could put males at risk of investing in another man’s children, and females at risk of mating with men who will not invest resources in their offspring. In two studies, Lambert and colleagues investigated if we are able to detect people’s unfaithfulness by simply watching them interact with their romantic partners for a few minutes.

These results suggest that the coders were somewhat accurate in spotting the cheaters.

In a second study, the researchers examined if perceptions of the participants’ trustworthiness and commitment might be at the root of these assumptions of unfaithfulness. This time, coders assessed videos of 43 couples completing the same blindfolded drawing task as those in the first study. But in addition to assessing infidelity, coders also rated how committed the participants were to their relationships and how trustworthy they seemed. The results showed that perceptions of trustworthiness and commitment mediated the relationship between actual and perceived (rater-coded) infidelity. In other words, the coders were accurate in assessing infidelity in part because they noticed that the unfaithful participants appeared less trustworthy and committed during the brief interaction.

This research represents just a first step in understanding how to detect infidelity. As the authors point out in their paper, the participants in this study were college students involved in dating relationships, so the results may not apply to the detection of infidelity in longer-term committed relationships or marriages. This study also examined gradations of infidelity (e.g., how physically intimate participants had been with someone else), differing from a more objective definition of cheating.

Still, these results suggest that objective observers can spot infidelity with some accuracy. But can we detect unfaithfulness in our own (or our friends’) relationships? Or are our own judgments too biased and clouded by wishful thinking? Research on detecting deception in romantic relationships suggests that even though we should know our partners well enough to catch them in a lie, we often don’t, because we want to believe in them.6 This desire to believe in our partners may prevent us from detecting their unfaithfulness, even if it’s clear to strangers.

Again, these results are only preliminary, but they suggest that when you have a hunch someone is cheating on a friend or family member, you may be onto something. But of course, unjustified suspicious jealousy is harmful!