The Science of Fidelity

The gene that produces vasopressin, bonding hormone produced in the brain, has long been known as the “fidelity gene.” Biologist Hasse Walum at the Karolinska Institute in Sweden, recently studied 552 different sets of twins to learn more about the gene related to the production of this chemical — to try to get a sense of how its presence affects marriages.

Over all, men who carried a variation in this gene were less likely to be married than those who didn’t. And the men who had gotten married were more likely to have had serious marital problems and unhappy wives. Of the men who carried two copies of the gene variant, about a third had experienced a serious relationship crisis in the past year, double the number seen in the men who did not carry the variant.

But a happy marriage is not necessarily one free of infidelity.

“It’s difficult to use this information to predict any future behavior in men,” Walum told Tara Parker-Pope, who reported about this on her column Well.

But the brain can be taught to resist temptation, Parker-Pope notes, citing a series of studies led by John Lydon, a psychologist at McGill University in Montreal that study people’s reactions to temptation.

In one of these studies, married men and women with high ranking in terms of fidelity were asked to rate the attractiveness of people of the opposite sex in a series of photos. They were then showed similar photos and told the persons were interested in meeting with them. In this instance, they gave photos of equally attractive people lower scores than they had the first time around.

“The more committed you are,” Dr. Lydon said, “the less attractive you find other people who threaten your relationship.”

In another study of 300 heterosexual men and women, half the participants were primed for cheating by imagining a flirtatious conversation with someone they found attractive. The other half just imagined a routine encounter. Afterward, the subjects completed fill-in-the-blank puzzles, which, unbeknown to the participants, were a psychological test used to reveal their subconscious feelings about commitment.

Differences arose between men and women who imagined the flirtatious fantasy. In that group, the men were more likely to complete the puzzles with the neutral words than words related to commitment.

THR_AT became “throat” to men and “threat” to women. LO_AL became “local” to men and “loyal” to women.

This prompted researchers to believe women may have early warning system to alert them to relationship threats.

This study doesn’t really say how people react when encountered by a threat to commitment, but the following one does. In this one, attractive actors and actresses were brought in to flirt with study participants in the waiting room. Afterward, the participants were asked questions about their relationships, especially how they would react to inappropriate behavior on the part of their partner, like forgetting to call.

Men who had been flirting were less forgiving, suggesting the previous flirtation had perhaps affected their commitment, making them more likely to find fault. Women who had been flirting, on the other hand, were more likely to be forgiving and make excuses for their partner in light of the hypothetical infraction, which suggests that the flirtation may have triggered a protective response in them.

“We think the men in these studies may have had commitment, but the women had the contingency plan — the attractive alternative sets off the alarm bell,” Dr. Lydon said. “Women implicitly code that as a threat. Men don’t.”

So can we train the brain to resist temptation? Another McGill study prompted male subjects in committed relationships to imagine running into an attractive woman on a weekend while they were away from their partners. Some were asked to fill in the sentence: “When she approaches me, I will __________ to protect my relationship.”

The subjects were then exposed to a virtual reality game in which two of the four rooms involved “subliminal messages of an attractive woman.” The men who had drafted a contingency plan before hand went into the rooms 25 percent of the time versus 62 percent for the other men.

Interesting — but what keeps people together? Arthur Aron, a psychologist and relationship researcher at Stony Brook University, thinks it’s “self-expansion” — how much a partner broadens your horizons and generally enhances your life.

In a study on the topic, couples are asked questions such as: how much does your partner provide a source of exciting experiences? How much has knowing your partner made you a better person? How much do you see your partner as a way to expand your own capabilities?

The Stony Brook researchers stimulated self-expansion in experiments by giving some couples mundane tasks, while others took part in a silly challenge with a time limit rigged to make them lose on the first two tries and win just barely on the last. The couples who did the silly challenge recorded increase in love and relationship satisfaction than those who did mundane tasks and did not experience the excitement and victory.

They theorize that couples who explore new places and try new things will tap into feelings of self-expansion, lifting their level of commitment.

“We enter relationships because the other person becomes part of ourselves, and that expands us,” Dr. Aron said. “That’s why people who fall in love stay up all night talking and it feels really exciting. We think couples can get some of that back by doing challenging and exciting things together.”

Photo by Elenah Neshcuet. Information from The New York Times.