Laugh and the whole world laughs with you -- Why the brain just can't help itself

Cricket commentator Jonathan Agnew's description of Ian Botham's freak dismissal, falling over his own stumps – "He couldn't quite get his leg over" – was all it took to send himself and the late Brian Johnston into paroxysms of laughter. Laughter is truly contagious, and now, scientists studying how our brain responds to emotive sounds believe they understand why.

Researchers at UCL (University College London) and Imperial College London have shown that positive sounds such as laughter or a triumphant "woo hoo!" trigger a response in the listener's brain. This response occurs in the area of the brain that is activated when we smile, as though preparing our facial muscles to laugh. The research, funded by the Wellcome Trust, Action Medical Research and the Barnwood House Trust, is published today in the Journal of Neuroscience.

"It seems that it’s absolutely true that 'laugh and the whole world laughs with you'," says Dr Sophie Scott, a Wellcome Trust Senior Research Fellow at the Institute of Cognitive Neuroscience, UCL. "We've known for some time now 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."