Why Laughter is Infectious

Infectious laughter seems to have a neurological basis;

“The team of played pleasant sounds, such as laughter or cheering, and unpleasant sounds, such as screaming or retching, to volunteers. They then monitored their brains with functional magnetic resonance imaging (MRI). All the sounds triggered neural responses in the premotor cortex of the brain — an area known to prepare groups of facial muscles to respond accordingly. When a person in the study actually smiled or laughed, the neural activity moved to a primary motor cortical region.

The neural response in the premotor cortex was, on average, twice as big for pleasant sounds than for unpleasant sounds, the team reports. Since the pleasant sounds have a bigger impact on the bit of the brain that activates muscles to respond in kind, the findings suggests that pleasant sounds are more 'contagious' than unpleasant ones.”