Long before modern brain imaging technologies illuminated the neurophysiological mechanisms that make laughter contagious, William James (1842-1910) observed, “We don’t laugh because we’re happy, we’re happy because we laugh.” Although philosophers and psychologists have speculated about the role that laughter plays in social bonding for eons, until recently, there was relatively little empirical evidence that explained why laughter is contagious for most of us. Or, the neural reasons some people are immune to the laughter contagion. That said, in the past few months, researchers have finally pinpointed some neuroscience-based answers to the million-dollar question: “Why is laughter contagious?“
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Recently, two separate clinical studies investigated the brain mechanisms of genuine, contagious social laughter from different angles. The first study, “Social Laughter Triggers Endogenous Opioid Release in Humans,” was published May 28, 2017, in the Journal of Neuroscience. The second study, “Reduced Laughter Contagion in Boys at Risk for Psychopathy,” was published online September 28, 2017, in the journal Current Biology.
In the first paper, Sandra Manninen and colleagues from the PET Centre in Finland along with researchers from the University of Oxford and Aalto University used positron emission tomography to identify that social laughter leads to endogenous opioid (endorphin) release in specific brain regions. The more opioid receptors a participant had in these regions of his or her brain, the more he or she was prone to contagious laughter.
Before the laughter-gauging brain scans, study participants observed their close friends laughing out loud as they watched comedy clips for 30 minutes. In a separate baseline experiment, the same participants spent 30 minutes alone in a sterile, laughter-free laboratory setting. Contagious social laughter was found to stimulate endorphin release in the…