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I cough, you cough: Why it's contagious

It's the height of cold and flu season, with people coughing and sneezing and blowing their noses (not to mention their germs) every which way.

But not all those coughs and throat clears stem from illness, says one expert.

"Humans aren't the rational creatures that we fancy ourselves to be. We're often beasts of the herd," says Robert Provine, a professor of psychology at the University of Maryland, Baltimore County (and frequent fount of weird information for The Body Odd). "We yawn when other people yawn. We laugh when other people laugh. And we cough when other people cough."

Provine, author of "Laughter: A Scientific Investigation" and a forthcoming book tentatively titled "Curious Behavior: Yawning, Laughing, Hiccupping and Beyond," says there's not been much research on the psychologically contagious elements of a cough, usually because "people who study coughing are interested in getting it to stop."

As a result, the mechanics behind the mimicry are a bit muzzy.

"We don't know at this time [what's behind it]," he says. "For example, is it because we have a brain mechanism that when it detects that sound, replicates it, as we seem to have for laughing and yawning? Or are we simply more likely to monitor our throat, to think, 'Oh, there's a tickle in my throat. I have to cough.' The apparent contagiousness of coughing may be due to enhanced self-monitoring and not to a contagious response in the way we find in contagious laughs and yawns."

But just because coughing hasn't been the subject of extensive study, doesn't mean it's not an intriguing topic, says Provine, who devotes a chapter in his upcoming book to the cough.

"You can cough when you have a tickle in your throat or you can cough to get someone's attention," he says. "Coughing can be a paralinguistic signal. It's a much richer behavior than most people think. People outside the medical community pay very little attention to coughing but they should."

Provine says coughing is essential to survival and much like eye blinking, is both consciously controlled and reflexive.

"You can choose to cough or it can happen reflexively," he says. "And coughing can be a life and death matter. It's a critical behavior for keeping the airways clear. If you can't cough, it can lead to the accumulation of fluid, which can lead to bacterial infection and pneumonia. So coughing is a big deal."

Juan Alonso-Rodriguez, a 55-year-old visual artist from Seattle, says he's fallen victim to a contagious coughing fit many a time and has also seen it happen in others.

"It's like a suggestion," he says. "I think it's that herd mentality. I hear someone clearing their throat or coughing and it puts the thought into my head that I should do the same. And I've noticed other people do it, too. Especially if you're in a meeting in a conference room. Somebody will cough and then you do the throat clear cough and then there's bound to be one or two other people that do it."

But even though he's a slave to the counterfeit cough, Alonso-Rodriguez says he doesn't really mind.

"I think it's hilarious," he says. "Somebody else coughs and there's nothing in my throat but I feel compelled to clear it. How stupid is that? It makes me feel very primitive."

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