Cheating on a spouse or significant other is sure to cause feelings of jealousy and hurt in the spurned partner.
But men and women differ on what part of cheating they think is the worst: Men tend to be more bothered by sexual infidelity, while most women are bothered more by emotional infidelity.
The prevailing explanation for this difference is the unique evolutionary roles played by men and women, but a new study suggests that it has more to do with the types of attachments people form in relationships.
The widespread evolutionary explanation posits that men rank sexual infidelity as the greater sin because over the eons they learned to be hyper-vigilant about sex, as they could never be absolutely certain that their children were actually theirs. Women, on the other hand, became more bothered by emotional infidelity, because they are concerned about having a partner to help raise their children.
A recent study found that men feel guiltier after a sexual indiscretion, while women feel guiltier after an emotional one.
The problem with the prevailing idea was that while men were more likely than women to rate sexual infidelity as worse than the emotional kind in studies, there was still a small subset of men who put emotional infidelity at the top of the list, said Kenneth Levy, a psychologist at Penn State.
This subset seemed to indicate that "there must be something else going on," Levy told LiveScience.
Attachment to others
Levy, who studies attachment in relationships, saw the results instead through the lens of his research and began to suspect that individual differences in how people view relationships could be affecting men's and women's views on infidelity.
Levy spoke of two types of attachment in relationships: dismissive and secure. A person with a dismissive attachment "doesn't see the value in relationships," he explained, describing them as "hyper-independent." Or, in other words, "most of us value our independence, but we also value our relationships. These individuals only value their independence, to the exclusion of relationships."
On the flip side, those with secure attachments see the value in relationships and are comfortable with the interdependency that comes with them, Levy said.
Levy thought those with a secure attachment style might be more likely to be bothered by emotional infidelity, while those with dismissive styles would see sexual infidelity as more of problem.
Sexual vs. emotional infidelity
To test this idea, Levy and his colleague Kristen Kelly had over 400 undergraduate students (about three-quarters were female) complete a standard assessment of attachment style in romantic relationships and also asked them which they would find more distressing — emotional or sexual infidelity.
The findings of their study, detailed in a recent issue of the journal Psychological Science, backed up Levy's hunch: Males with a dismissive style found sexual infidelity more bothersome, while men with a secure style rated emotional infidelity as worse. Somewhat unexpectedly, the same was found in females.
"So it seems to be that this concern about sexual infidelity seems to be tied to dismissiveness attachment whether you're a male or a female," Levy said.
While it would seem like those with dismissive attachment styles wouldn't care about either type of infidelity, Levy notes that this kind of attachment is defensive; dismissive types distance themselves from relationships to avoid deep-seated feelings of vulnerability. Their concern over sexual infidelity shows a concern about their connections to others, but on an unemotional level, Levy said.
Levy suggests that this attachment model of jealousy could replace the standard evolutionary one, though it is itself rooted in evolution. Attachment is a mechanism that helps people become connected to other people — an important survival technique in human society. These attachments are learned from our earliest relationships, with our parents or other caregivers, and seem to carry on through life, as our most important relationships shift from our parents, to our friends, and finally to romantic relationships.
So it would seem that the attachment styles adults display in relationships were learned from early on, and not programmed in.
This understanding could point to ways of reducing feelings of sexual jealousy, "which research shows is tied to all sorts of maladaptive behaviors," by promoting secure attachment in children or exposing adults to the benefits of this kind of attachment, Levy said.
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Andrea Thompson is an associate editor at Scientific American, where she covers sustainability, energy and the environment. Prior to that, she was a senior writer covering climate science at Climate Central and a reporter and editor at Live Science, where she primarily covered Earth science and the environment. She holds a graduate degree in science health and environmental reporting from New York University, as well as a bachelor of science and and masters of science in atmospheric chemistry from the Georgia Institute of Technology.