You may be oblivious to your partner's cheating ways, but that doesn't mean everyone else is. In fact, a fascinating new study suggests that strangers can quickly spot a cheater just by watching how couples get along.
"People can determine whether complete strangers were cheaters or non-cheaters by simply watching them interact for a short period of time," Dr. Nathaniel Lambert, an assistant professor at Brigham Young University's School of Family Life and the lead author of the study, told The Huffington Post in an email.
For their study, researchers rounded up 51 undergraduate students at Florida State University and their romantic partners. Each student completed a questionnaire about his/her emotional and physical infidelity in the relationship. Then the couples were videotaped for about four minutes as they did a drawing task in which one partner was blindfolded and the other guided his/her partner on what to draw.
The videos then were shown to six strangers, who were asked to assess how likely each student was to cheat on his/her partner.
What did the researchers find? The strangers' guesses were strongly correlated with the students' self-reported infidelity. The researchers conducted a second experiment with 43 other couples and five other strangers. Once again, the same correlation was observed. The strangers weren't right every time, Lambert said, but their ability to spot cheaters was significantly above chance.
More research is needed to determine what caused the strangers to suspect infidelity. But study co-author Dr. Frank Fincham, director of Florida State University's Family Institute, offered an explanation as to why humans have this surprising ability.
"Possibly because it confers an evolutionary advantage," Fincham told The Huffington Post in an email. In other words, the ability to spot infidelity may help ensure that we don't wind up spending our time and energy raising offspring that aren't our own.
The study was published online in the journal Personal Relationships on September 18, 2014.
Want to learn more about the curious science of infidelity? Check out six ways to spot a cheater in the "Talk Nerdy To Me" video below.