Why You’re More Grossed Out by Strangers Than Your Friends

By

Let’s play a game of “Would You Rather?” Say you’re out at a restaurant with a friend and you accidentally knock your water onto your shirt. We’re not talking about a little spill, either; this is the whole glass, and it was a big one, and now you’re sopping wet and also it’s pretty cold outside. Luckily, your friend happens to have just come from the gym and has a couple of shirts in the gym bag tucked under the chair. They’re both a little sweaty still (sorry) — one of them belongs to your friend; the other one, you’re told, was just lying on the floor of the locker room. (As with all would-you-rather games, it’s important not to ask why your friend boosted a stranger’s damp gym clothes; this is the hypothetical world you live in, and you must accept it.)

Which one did you take? Your friend’s, right?

It’s funny — sweat is sweat, and, in theory, all of it should be equally gross. But there’s something about knowing someone that mitigates the grossness of their bodily fluids. Not that you’d want to wear your friend’s sweaty clothes if clean ones were available, but it’s still a more appealing choice than doing the same with a total stranger. In Scientific American this week, Daniel Yudkin reported on new research that looks at why that’s the case.

In the study in question, published in the journal Proceedings of the National Academy of Sciences, researchers from the University of St. Andrews in Scotland divided St. Andrews students into two groups. Half were led to believe that the study was about college students in general, and the other half that the researchers were studying St. Andrews students in particular.

The study authors then took three sweaty shirts that had been worn by the same person — one plain white, one with the St. Andrews logo, and one with the logo of Scotland’s University of Dundee — and asked the participants to smell them. To measure disgust, the study authors left a container of hand sanitizer in the room, reasoning that the more grossed out someone was by holding a sweaty shirt, the quicker they’d be to reach for it after they put the shirt down.

Across the board, people were pretty disgusted by the plain shirt, bolting for the sanitizer immediately after handling it, and were generally okay with the St. Andrews shirt. Things got a little more complicated, though, with the Dundee shirt: The volunteers who had been told the study was about St. Andrews students found it more repulsive, washing their hands more quickly, than the ones who believed the study was just about college students.

The researchers believe the reason for the discrepancy, Yudkin explained, lies in the different ways the students had been primed to think about in- and out-groups. If you’re thinking of yourself as a college student, you feel an affinity with all other college students; if you bring university rivalries into the mix, that affinity disappears, replaced by a more selective loyalty. The disgust the students felt toward a given T-shirt, in other words, corresponded with their perceived level of closeness with its anonymous owner — a finding, Yudkin wrote, that helps to illustrate one more facet of the complicated phenomenon that is group identity:

First of all, it corroborates the notion that people think of their own groups as an extension of the self … Furthermore, it highlights the profound impact of our group memberships on our perception of the world. It is well known that people favor friends, family members, even members of their same community. Such groupish tendencies underlie many of the divisions in the world we see today, from conflicts in the Middle East to racial tensions in the U.S. It is fascinating to see just how deep-rooted these prejudices are, extending not just to explicit attitudes about friends and strangers but also to tendencies as hard-wired and intrinsic as disgust.

On the other hand, he added, the fact that the two groups of study participants had such different reactions to the Dundee shirt also “showed just how malleable these group memberships can be.” Our tendency toward groupishness may be hard-wired, in other words, but there are constantly shifting factors that determine whom we consider to be an “other” worthy of wariness and, all too often, disgust.