Growing up, they teach you that swearing is a bad habit -- but no one ever explained why it was a bad habit for so many people. If swearing has negative social repercussions -- and certainly in some social situations it still does -- then why are people compelled to do it? A new study in the journal NeuroReport may have an answer. "Swearing is such a common response to pain that there has to be an underlying reason why we do it," says psychologist Richard Stephens of Keele University in England, who led the study. And indeed, the findings point to one possible benefit: "I would advise people, if they hurt themselves, to swear," he adds. You heard him, kids: a scientist is telling you it's OK to drop the f-bomb now and then.

The study asked 67 student volunteers to immerse their hands in ice-cold water for as long as they could physically stand to. One group was allowed to repeat or chant a neutral word of their choosing during the exercise, while another group of students was allowed to swear. Turns out the students with the dirtiest mouths were also able to withstand the cold water for longer -- 40 seconds longer, on average.

From Scientific American:

How swearing achieves its physical effects is unclear, but the researchers speculate that brain circuitry linked to emotion is involved. Earlier studies have shown that unlike normal language, which relies on the outer few millimeters in the left hemisphere of the brain, expletives hinge on evolutionarily ancient structures buried deep inside the right half.

One such structure is the amygdala, an almond-shaped group of neurons that can trigger a fight-or-flight response in which our heart rate climbs and we become less sensitive to pain. Indeed, the students' heart rates rose when they swore, a fact the researchers say suggests that the amygdala was activated.

That explanation is backed by other experts in the field. Psychologist Steven Pinker of Harvard University, whose book The Stuff of Thought (Viking Adult, 2007) includes a detailed analysis of swearing, compared the situation with what happens in the brain of a cat that somebody accidentally sits on. "I suspect that swearing taps into a defensive reflex in which an animal that is suddenly injured or confined erupts in a furious struggle, accompanied by an angry vocalization, to startle and intimidate an attacker," he says.

The study's authors warn that there's a catch, though. Swearing may be able to help dull pain, but the more it's used, the less effective it becomes. In other words, if you lace four-letter-words into every sentence like a character in a Tarantino flick, those same words aren't going to do much for you when you get gut-shot or someone slices your ear off with a butterfly knife. So for purely practical and self-interested reasons, it's not a bad idea to watch your mouth -- most of the time.

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