Why We Never Find Our Family Members Stinky

New research finds body odor is less disgusting if we share an identity with the smelly person in question.
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(Photo: sarahemcc/Flickr)

(Photo: sarahemcc/Flickr)

Tribalism has made a big comeback in the 21st century. In the United States and around the world, we're clinging ever more tightly to "people like us" and looking at outsiders with suspicion, or worse.

How deep is this impulse? New research from Great Britain suggests it can be found at the sensory level.

In two experiments, students whose personal identities were linked to their university were less disgusted by a sweaty T-shirt if it carried their school's logo. Body odor, it seems, isn't as off-putting if the person doing the perspiring is perceived as a member of our clan.

"It is impossible to work with people if you cannot stand their physical presence."

"Group identities affect not only social perceptions, but also our basic sensual experiences," writes a research team led by Stephen Reicher of the University of St. Andrews and John Drury of the University of Sussex. Their paper is published in the Proceedings of the National Academy of Sciences.

As New York University psychologist Jonathan Haidt has written, disgust is a fascinating phenomenon in that it began as a vitally important physical sensation—it keeps us from coming into contact with substances that carry disease—but gradually crept into the moral realm, getting triggered by unfamiliar cultural habits or sexual practices.

For some, a perceived challenge to one's beliefs or personal identity can elicit this unpleasant physical sensation. One example: A 2011 study found self-described Christians were more likely to describe a beverage as disgusting after they were exposed to an incompatible belief system.

In this study, the researchers approached the issue from the opposite perspective, asking if an item that is physically disgusting (a sweaty T-shirt) is less repulsive if it was soiled by "one of our own."

The first experiment featured 45 female students from Sussex University, who were told its intent was to determine how well they could perceive pheromones. Their introductory information sheets had subtle differences, with some stating the experiment was "concerned with the abilities of Sussex University students," while others said it was tracking the abilities of students in general or, simply, "individuals."

All took a "big smell" of a shirt that had been "worn for a week by a male research assistant, both during daily physical exercises and in bed." It bore a large logo of a different school, Brighton University. After smelling it, the participants answered a series of questions measuring their emotional reaction to the encounter.

Participants who had been approached simply as "a student" were less disgusted by the experience than those who were approached as a "Sussex University student." Further analysis revealed that "perceived similarity" to the shirt's owner—a fellow student, albeit from a different institution—led to the lower level of disgust.

The second experiment featured 90 students from St. Andrews University who sniffed a smelly T-shirt emblazoned with either the logo of their school, that of a nearby rival university, or no logo at all. Similar to the first experiment, their instruction sheet stated that researchers were measuring the ability of either "St. Andrews University students" or, simply, "students."

The key result: Participants whose identity as a St. Andrews student was made salient "went to wash their hands more quickly, and used more soap," after smelling a shirt with either their rival's logo or no logo.

They rushed to the hand sanitizing station after smelling the shirt with the rival school's logo, getting there in three and one-half seconds (on average). In contrast, those who smelled a shirt with their own school's logo ambled over; it took about six seconds. It seems they were significantly less bothered by the stink.

These results make sense from an evolutionary perspective in that members of a prehistoric tribe couldn't collaborate very easily if they found one another revolting. "Groups involve not only a gathering of minds, but also of sweaty, smelly, tactile bodies," the researchers note. "It is impossible to work with people if you cannot stand their physical presence."

The good news is that disgust varied according to how participants identified themselves at any given moment. Thinking of yourself as a "St. Andrews student" reduced disgust only for fellow St. Andrews students, but conceiving your identity in broader terms—as "a student"—reduced disgust for all students.

This is consistent with the results of another new study we described last month, which found bias toward members of a different race can be reduced by reminders of your mutual membership in some other, non-racial group. Similarly, it appears disgust can be counteracted by reminders of common interests or experiences.

So if you're reluctantly sharing a cramped space with a stranger, strike up a conversation and discover what you have in common. With any luck, both of you will literally breathe easier.

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Findings is a daily column by Pacific Standard staff writer Tom Jacobs, who scours the psychological-research journals to discover new insights into human behavior, ranging from the origins of our political beliefs to the cultivation of creativity.

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