Why Creepy People Give Us The Chills

Why do you get the willies when you interact with someone creepy? Science has the answer!

Social psychologist Pontus Leander set up an experiment to find how mismatched body language can send shivers down your spine:

An experimenter separately interviewed 40 college undergraduates, subtly tweaking her behavior from person to person. In some cases she acted chummy, dropping words like "awesome" into the conversation. In others, she was much more formal. At the same time, the interrogator alternated between mimicking the students' body language—slouching when they slouched or fidgeting when they fidgeted—and avoiding mimicking entirely.

The students then filled out a survey designed to discover how cold or warm they felt. It may sound strange, Leander says, but people often begin to feel cold when their social lives turn uncomfortable or otherwise unfulfilling—they literally get the chills. Individuals that describe themselves as lonely, for instance, take more frequent hot showers than their peers. And, sure enough, the students in the study reported that they felt colder when the experimenter's social cues seemed somehow off—that is, when she was either acting friendly but not mimicking or seemed professional and did mimic—as the group will report in an upcoming issue of Psychological Science.

The students could hardly be blamed for getting the willies, Leander says. By acting congenial or not, the experimenter had set up basic expectations for the interview: in some cases, "I want to be friends," and in others, "I'd rather keep this professional." Her body language, however, sent the exact opposite message. On an instinctual level, such a deviation from social norms can feel awkward—or downright creepy. "You can feel in your gut that it's not a good thing," he says. It's a good reminder of just how much humans are swayed by reactions that they're not consciously aware of.