Most people who are cheating on their romantic partners don’t want to be caught. They don’t want their partners to recognize their infidelity, and they don’t want other people to be able to tell, either.
So is it possible for people to just watch a couple and know whether one of the partners is cheating on the other? If so, how long would you have to know the possible cheater? Would you need to be a close friend or maybe a relative who has known the person their whole life? Would you need to be the person who is getting cheated on?
The romantic partner who is getting betrayed by their partner may well be the last to know. Often, they just really do not want to know – they are motivated to believe that their partner would never do that to them. Careful research shows that romantic partners are sometimes worse than complete strangers at knowing when their partner is lying.
In a recent set of studies, psychologists made the brazen prediction that total strangers could recognize, at a level that is better than chance, whether someone is cheating on their romantic partner, and that they could figure that out by watching the couple interact for only about four minutes!
In each of the two studies, college student couples interacted with each other for about 3-5 minutes. Their interactions were videotaped. One person in each couple completed a measure assessing any physical or emotional infidelity to their partner. (Of course, their answers were for the researchers’ eyes only.) The videotapes of the interactions were shown to complete strangers, who were asked to focus on the key person (the one who reported on his or her own infidelity). Those strangers reported their impressions of whether that person was cheating on their partner, by answering questions such as “How likely do you think this person has had sexual intercourse with someone other than his/her partner?” In the second study, the strangers also indicated their impressions of how committed to their romantic partner the person seems to be, and how trustworthy the person seems.
Based on only about 4 minutes of observing the couples, the strangers could tell, to a moderately successful degree, who was cheating and who was not. Their impressions correlated significantly with the key persons’ own reports of their cheating. The strangers seemed to use their sense of the person’s trustworthiness and commitment to their partner as clues to whether they were cheating.
The couples in the study and the strangers who observed them were all college students, and the strangers were almost all women, so as social scientists like to say, “More research is needed.” It is interesting, though, that people can get a pretty good sense of who is a committed romantic partner and who is a cheater from such a “thin slice” of their behavior.
Reference: Lambert, N. M., Mulder, S., & Fincham, F. (2014). Thin slices of infidelity: Determining whether observers can pick out cheaters from a video clip of their interaction and what tips them off. Personal Relationships, 21, 612-619.