Everyone knows the phrase “laughter is the best medicine.” Growing scientific evidence expands on the benefits of laughter with one study reporting the activity may prevent future heart attacks. A corollary investigation of the new attention to laughter as a therapeutic medium is the question, “Is laughter contagious?”

British scientists studied how our brain responds to emotive sounds in a report published in the Journal of Neuroscience.

Is Laughter Contagious?Researchers at UCL (University College London) and Imperial College London found 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.

“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.”

The research team played a series sounds to volunteers whilst measuring their brain’s response using an fMRI scanner. Some of the sounds were positive, such as laughter or triumph, whilst others were unpleasant, such as screaming or retching.

All of the sounds triggered a response in the volunteer’s brain in the premotor cortical region, which prepares the muscles in the face to respond accordingly, though the response was greater for positive sounds, suggesting that these were more contagious than negative sounds. The researchers believe this explains why we respond to laughter or cheering with an involuntary smile.

“We usually encounter positive emotions, such as laughter or cheering, in group situations, whether watching a comedy programme with family or a football game with friends,” says Dr Scott.

“This response in the brain, automatically priming us to smile or laugh, provides a way of mirroring the behaviour of others, something which helps us interact socially. It could play an important role in building strong bonds between individuals in a group.”

Source: Wellcome Trust