Laughter is contagious, and there is a scientific explanation for this
You’ve almost certainly experienced it: someone nearby starts laughing, and within seconds you can’t hold back either, even if you didn’t understand what was funny. A new study from the University of Göttingen explains why the brain literally forces us to join in with other people’s laughter — and why trying to stop often only makes things worse.
How the Brain Makes Laughter Involuntary
Research shows that there are two types of laughter: involuntary, uncontrollable laughter — and polite, social laughter (when a friend tells a joke and you laugh because you like the friend, not because the joke is funny).
Different brain regions are responsible for each type. Voluntary laughter originates in the frontal zones that control movement planning — from there, a signal travels through the motor cortex to the facial muscles. This is that polite chuckle at your boss’s bad joke.
Involuntary laughter, however, is controlled by the emotional system — the amygdala (the center for processing emotions and threats) and deep brainstem structures. It fires before you have time to consciously process anything. That’s why sometimes you burst into laughter at the most inappropriate moment: the emotional system outpaces the thinking part of the brain.
It’s important not to confuse ordinary uncontrollable laughter with a rare neurological disorder — pseudobulbar affect. This condition is associated with brain damage and manifests as brief, intense, and uncontrollable episodes of crying or laughing that can be triggered by emotionally neutral stimuli. This disorder inspired the character of Arthur Fleck in the 2019 film “Joker” — Joaquin Phoenix studied videos of patients to prepare for the role.
The Role of Social Environment in the Contagiousness of Laughter
Have you noticed that everything seems funnier when you’re with friends? It’s not an illusion. We laugh 30 times more often in the presence of another person than when alone. This fact, established in the classic works of psychologist Robert Provine, has been confirmed again and again.
A research team from the University of Göttingen conducted three experiments with 121 participants. Using facial electromyography, scientists recorded the tiniest muscular reactions — so subtle they would be invisible to the naked eye. Volunteers listened to jokes and tried not to laugh — they distracted themselves, controlled their facial expressions, or convinced themselves the joke wasn’t funny.
Distraction and facial suppression were most effective at reducing visible muscle reactions, while reappraisal of humor had a smaller but more sustained effect. Notably, only reappraisal (when a person convinced themselves the joke wasn’t funny) actually reduced the subjective feeling of amusement.
Laughing with friends is one of the most social forms of human behavior
But here’s the key finding: “Even these strategies reached their limits in certain social situations,” explains Professor Anne Schacht from the Institute of Psychology at the University of Göttingen. “When participants heard another person’s laughter, controlling their own laughter became significantly harder. This shows how strongly our emotional reactions depend on the presence of other people.” In other words, the sound of someone else’s laughter acts as a signal to the brain: “This is funny, join in!” — and conscious effort often simply cannot override this automatic reaction.
What Happens in the Brain When We Hear Someone Else’s Laughter
The mechanism behind the contagiousness of laughter is linked to how the brain perceives sounds. All sounds trigger a response in the premotor cortex — the area that prepares facial muscles for a response. But for positive sounds (such as laughter), this neural response is on average twice as strong as for negative sounds. The brain essentially automatically “rehearses” a smile when it hears someone else laughing.
Neuroscientist Sophie Scott from University College London notes: we constantly mirror our conversation partner’s behavior — copying words, gestures, and postures. Laughter turns out to be yet another form of such mirroring behavior — only at the level of brain activity.
Interestingly, contagious laughter is a learned behavior. Behavioral contagion is an acquired skill: infants don’t “catch” other people’s laughter. This means the mechanism of social contagion develops as the child grows and integrates into society.
Premotor cortex activity when perceiving the sound of laughter
Why Laughter Is So Hard to Stop
Another reason it’s difficult to stop laughing is that the brain literally rewards you for it. When people laugh together, the brain releases natural “pleasure chemicals” — endogenous opioids.
A study conducted using positron emission tomography (PET) showed that shared laughter enhances pleasant sensations and stimulates the release of endogenous opioids in the thalamus, caudate nucleus, and anterior insular cortex. Endogenous opioids are the body’s own painkillers and “happiness hormones,” primarily endorphins.
These substances reduce pain, create a sense of well-being, help cope with stress, protect the heart, and even regulate appetite. It turns out that laughter activates a powerful reinforcement system in the body — and the brain really doesn’t want to turn it off.
The evolutionary logic is also fascinating. In primates, mutual grooming — picking through each other’s fur — serves to strengthen social bonds. But grooming only works one-on-one and takes time. Scientists suggest that shared laughter may have evolved as a form of “group grooming,” allowing the simultaneous release of opioids in all members of a group. This may have helped our ancestors maintain much larger social networks than other primates.
Can You Actually Learn to Suppress Laughter?
The results of Dr. Schacht’s research showed that distraction, facial control, and reappraisal of humor do help suppress laughter — at least partially. But suppression has a downside.
In one of the experiments, participants were asked to suppress certain thoughts or reactions. When people tried not to think about something, they later thought about it even more. The same happened with laughter: those who tried not to laugh ended up laughing even harder afterward. Scientists call this the “rebound effect.”
Trying to hold back laughter in a serious meeting — a situation familiar to many
According to Dr. Schacht, emotions, the brain’s reward system, facial muscles, and the people around us — all of these simultaneously contribute to uncontrollable laughter. It’s a “combination of factors” that makes laughter one of the hardest emotional responses to suppress.
