Contagious Laughter
The new study can be compared with with one by researchers at University College (UCL) and Imperial College London published in the Journal of Neuroscience in 2007 showed a possible mechanism for contagious laughter. Positive sounds like laughter trigger a response in the area of the listener's brain activated when we smile, as though preparing facial muscles to laugh.
Dr Sophie Scott, senior research fellow at the Institute of Cognitive Neuroscience said:
"It seems that it's absolutely true that 'laugh and the whole world laughs with you'. 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."
Researchers played volunteers various sounds while measuring brain responses using an fMRI scanner. Some sounds were positive, for example laughter or triumph. Others were unpleasant, such as screaming or retching. All triggered a response in the premotor cortical region of the brain, which prepares facial muscles to respond accordingly. However, the response was greater for positive sounds, suggesting that these were more contagious than negative examples. The researchers believe this explains why we respond to laughter or cheering with an involuntary smile.
Sophie Scott commented:
"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. 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."