It’s no joke: Laughter is contagious


Written on Thursday, December 14, 2006 by Gemini

Ha, ha, ha. Did you know even listening to a laughter can make you smile? A study by UK researchers has found laughter tickles the brain, which means that if you see two people laughing, chances are that you will smile—even if you don’t realise it, reports LiveScience. According to the new study, laughter truly is contagious: the brain responds to the sound of laughter and preps the muscles in the face to join in the mirth.

“It seems that it’s absolutely true that ‘laugh and the whole world laughs with you,” said Sophie Scott, a neuroscientist at the University College London. “We’ve known for some time that when we are talking to someone, we often mirror their behaviour, copying the words they use and mimicking their gestures. Now we’ve shown that the same appears to apply to laughter, too—at least at the level of the brain.” Scott and her fellow researchers played a series of sounds to volunteers and measured the responses in their brain with an fMRI scanner. Some sounds, like laughter or a triumphant shout, were positive, while others, like screaming or retching, were negative.

All of the sounds triggered responses in the premotor cortical region of the brain, which prepares the muscles in the face to move in a way that corresponds to the sound. The response was much higher for positive sounds, suggesting they are more contagious than negative sounds—which could explain our involuntary smiles when we see people laughing.

The team also tested the movement of facial muscles when the sounds were played and found that people tended to smile when they heard laughter, but didn’t make a gagging face when they heard retching sounds. She attributes this response to the desire to avoid negative emotions and sounds. The contagiousness of positive emotions could be an important social factor. Some scientists think human ancestors may have laughed in groups and that laughter may have been a precursor to language.

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