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An often-unacknowledged Halloween ritual, one nearly as sacred to the holiday as the consumption of candy or the carving of jack-o-lanterns, is the tradition of shamelessly lying to children.

“Oooh, what a scary ghost,” an enthusiastic adult will tell a trick-or-treater draped in a sheet. “Are you a real werewolf?” they’ll ask a kid whose costume consists of plastic fangs and painted-on whiskers. “Good thing there’s no full moon tonight!”

The more self-aware of these faux-monsters, cognizant of the fact that they’re fooling no one, will endure these doorstep pleasantries as a price to be paid for free candy. But often, the younger and more wide-eyed among them will beam beneath their masks, reveling in the belief that they are, in fact, scary.

Here’s the thing, though: They are, in fact, scary.

Okay, maybe not scary scary, not in the Halloweeny, ghouls-and-goblins kind of way. But research has shown that dressing up and traveling in packs—two things kids do in abundance on this particular holiday—can make them a little bit, well, monstrous.

In one 1976 study, for example, psychologists covertly observed the behavior of more than 1,000 trick-or-treaters at 27 homes in Seattle. Inside the doorway of each house was a similar setup: one bowl filled with candy and one bowl filled with pennies and nickels, both placed on a low table near the entryway. In each case, a researcher would answer the door and chat with the children standing outside, sometimes asking their names, sometimes letting them stay anonymous. After instructing the kids to take only one candy apiece, the researcher would announce that she had to return to her work in the other room, where she would watch through a peephole.

The sense of anonymity, as it turned out, made a big difference: The kids who were allowed to remain anonymous stole money and extra candy roughly three times as often as those who had given their names to the researcher. Kids who came in groups, anonymous or no, were more than twice as likely to steal as those who came alone.

In a similar, smaller study from 1979, researchers set out to replicate the same effect by watching 58 costumed kids between the ages of nine and 13—all unaccompanied by adults—who were told to take two, and only two, pieces of candy. Consistent with the research from three years earlier, participants whose getups included masks were significantly more likely to violate the instructions, grabbing a healthy fistful 62 percent of the time (versus 37 percent for their unmasked counterparts).

The authors of both studies explained their results by invoking a social-psychology phenomenon known as deindividuation, in which a person’s individual identity is subsumed by the identity of a group. Beneath the cover of a ghostlike sheet or behind a pack of friends, inhibitions can dissolve in a way that makes antisocial behavior much more appealing. Someone traveling with a pack of costumed trick-or-treaters, in other words, might be drawn to mischief in a way he wouldn’t be if roaming the neighborhood on his own, in jeans.

Not that it stops after the early years. In a 1993 study of around 1,200 college students—the only group who may love Halloween more than kids—researchers found that those who dressed up for the holiday  were also more likely to celebrate by drinking alcohol (the grown-up version of stealing candy, I guess). Those whose costumes involved a group, the study noted, were also more likely to use drugs over the course of the night.

But the idea that the clothes make the man—or the kid—can be used for good as well as evil. In one 2012 study on the concept of “enclothed cognition,” or the ways in which a person’s outfit can affect their behavior, volunteers who wore doctors’ coats performed better on attention and memory tasks than those who wore street clothes. In an interview with The New York Times, the study author described his own confidence-boosting enclothed-cognition moment from a previous Halloween, when he came to class decked out in long coat, fedora, and cane: “When I entered the room, I glided in,” he said. “I felt a very different presence.”

So, parents scrambling to find their children last-minute costumes, listen up: For the good of humanity, please, put down the bandit mask, the witch hat, the horns and pitckfork. Your kid would look great in a robe and a halo. Honestly.

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