Laughter science: Scientists track why we laugh when others do
Comment on this story
My three little girls love to watch pets do silly things. Almost every day, they ask to see animal videos on my phone and are quickly amused. But as soon as my 7-year-old lets out a belly laugh, the floodgates of laughter open and her two sisters double over, too.
This is exactly what science would predict.
“Laughter is a social phenomenon,” says Sophie Scott, a neuroscientist at University College London who has studied laughter and other human reactions for more than two decades. Scott co-authored a study showing how the brain reacts to the sound of laughter by preparing facial muscles to contract, laying the groundwork for laughter to spread from person to person.
“Contagious laughter shows love and belonging,” says Scott. “Even being around people who expect to be funny will make you laugh.”
Scientists have yet to definitively find a funny bone, but they are discovering nuances about the impulse to laugh. Positive psychological and physiological responses to laughter include reduced symptoms of depression and anxiety, increased feelings of relaxation, improved cardiovascular health, release of mood-enhancing endorphins, and even increased pain tolerance.
Laughter has also been shown to reduce stress levels. “Cortisol is a stress hormone that laughter lowers,” says Scott, adding that the anticipation of laughter also “lowers your adrenaline” and the body’s higher fight response. “All of these things contribute to making you feel better when you’re laughing,” she says.
Because people are wired to mirror each other, laughter spreads across a room just like yawns, says Lauri Nummenmaa, a brain researcher and professor at the Aalto University School of Science in Finland, whose work appears in a recent special issue on laughter in the Royal Society journal. .
“We just copy other people’s behavior and laughs,” says Nummenmaa. “The act of someone else laughing is first perceived when seen or heard, and this sensory information is then transformed into the same area of the observers’ brain.”
Studies also show that laughter can strengthen relationship bonds. This is partly because people naturally want to be around those who make them feel good, as laughter does. “We crave the company of individuals who can give us such feelings,” says Nummenmaa. “Laughter is a sort of molecular building block of friendship.”
Scott adds, “You’re much more likely to get a laugh from someone you know.”
Sending a wordless play signal
Contagious laughter is not necessarily a phenomenon unique to humans. Great apes, for example, have been documented to behave similarly.
“Laughter is a play signal in humans and many other animals,” says Disa Sauter, a professor of social behavior at the University of Amsterdam. “Used in rough and tumble games between species.”
The play-laughter connection is an important one. Certain sounds, or vocalizations, serve as important signals throughout the animal kingdom that playtime has begun.
“Vocal play signals often accompany other non-vocal behaviors, such as the play face in primates … or the play arch in dogs,” according to a 2021 study in the journal Bioacoustics. Signs help distinguish threatening actions from play fighting and wrestling.
Behavioral scientists also want to understand the role that laughter plays in children playing together. “We need to understand how laughter is used by children to signal that rough play is just play and not a real fight,” says Nummenmaa.
Malicious laughter and laughing attacks
Sure, you can laugh alone, but the contagious nature of laughter means we’re more likely to laugh harder and longer in a group, like at a comedy club or a movie theater.
Psychologist Robert Provine showed that “you’re 30 times more likely to laugh with other people than you are with yourself,” says Scott. In his seminal book, Laughter: A Scientific Inquiry, Provine wrote that “the contagious laughter response is immediate and involuntary, involving the most direct communication possible between humans: brain to brain.”
Researchers are working to determine different types of laughter and how people adopt each in different settings; think malicious laughter to signal authority, or nervous laughter to express insecurity.
“Laughter has many subtle rules that make adults very attuned to when it’s socially appropriate,” says Harry Witchel, a physiologist and neuroscientist at Brighton and Sussex Medical School in Brighton, England.
There are circumstances, he notes, when people laugh at something that is not humorous: “Laughter is regularly associated with joy, relief, tickling, sudden incongruity, social discomfort, dominance, humiliation of another, and many other causes.”
And there are other times when the contagious nature of laughter becomes problematic.
In “Laughter,” Provine described “epidemics of laughter” that have occurred throughout history, including “holy laughter” that appeared in some churches. There was also the “laughter plague” that struck many Central African schools beginning in 1962: contagious “laughter attacks” among some groups of students lasted from several hours to several days and continued until two schools had to be closed for long periods of time.
Scott has also studied such events and was one of more than 40 researchers and academics who contributed to “Cracking the Laughter Code: Laughter Through the Lenses of Biology, Psychology, and Neuroscience,” a September 2022 issue of the journal Proceedings of the Royal Society. B. Their work is part of a long scientific effort to analyze what makes people jump, cringe, laugh, dance and more.
Although scientists have discovered much about the health benefits of laughter and its contagious element, much remains unknown, including how contagious laughter is learned in the first place.
“Kids aren’t born doing this,” says Scott. “All we know is that people learn to laugh contagiously eventually, but we don’t know how or when exactly it starts.”
More stories about health and wellness
View 3 more stories