Laughter’s Secret Purpose

[This piece originally appeared in the Fall 2012 issue of The Brain from Discover magazine.]

While a trilling ha-ha-ha or hearty chortle might seem like the simplest and most effortless thing in the world, but laughter is actually a multifaceted neurological process that recruits circuitry from all over the brain. And despite its tremendous familiarity, laughter has received little attention from science, at least until recently. Sophie Scott, a cognitive neuroscientist at the University College, London, and her colleagues are using brain scans and field studies to document the diversity of human laughing behavior. They find that laughter is both universal and deep-seated, playing a crucial role in the social bonds that have helped us survive as a species. Laughter makes us happy because it ties us together, she believes. When it comes to parsing its cognitive significance, she finds the old verse has it right: Laugh, and the world laughs with you.

Laughter seems pretty simple: Something funny happens, and we laugh. What is the deeper aspect you are studying?

If you ask people what makes them laugh, they’ll tell you that they laugh at jokes. But if you go out in the field and observe people laughing, you’ll see that most of this behavior occurs in conversation. When you laugh, you’re saying that not only do you find something amusing, but that you’re agreeing with somebody, that you’ve got something in common with them, or that you’re part of the same group. It’s a social emotion: You laugh more if you’re with other people than if you’re on your own.  You laugh more with people that you like, you laugh more if you’re with people you would like to like you. Most of the work of laughter is to help you form bonds with people, maintain those bonds, and demonstrate that the bonds exist.Your description suggests that humor should translate across cultures. Is that true?

One of my PhD students drove a van around the Namibian desert showing videos of UK people to members of the Himba tribe. We also showed videos of the Himba to UK people. We found that, just as people can recognize emotions such as fear, anger, disgust, and surprise across cultures by their facial expressions, they can do the same through their vocal expression.  But vocal expressions of triumph, relief, and sensual pleasure were not well recognized across cultures. The only positive emotion which was recognized in both directions was laughter.

Doe that mean laughter an ancient evolutionary feature?

It seems to be associated with mammals.  You find laughter in chimpanzees, and gorillas, and even in rats. We know about rats because [Washington State University neuroscientist] Jaak Panksepp was investigating the fear response and looking at the sounds rats make when they’re distressed. Rats are very small and they make a high-pitched sound, so in order to hear their vocalizations you have to record the sound and slow it down. He noticed that the rats made a very specific sound when they were playing with each other, and he thought, “I wonder if that’s laughter.”  So he started tickling rats—which sounds like the best job in the world, by the way—and the rats all made the same sound when they were tickled.  They would also make the sound when they saw the person who normally tickled them come in the room. Interestingly, the rats who laugh more when tickled as adults are the rats who were tickled abundantly when they were young.

So tickling and laughter are intimately connected? Why do we laugh when other people tickle us but not when we tickle ourselves? Is it because laughter is social?

The very first appearance of laughter tends to be when parents or caregivers tickle young babies. It’s very easy to tickle a baby and get it to laugh, and when it does you feel like the most hilarious person in the world, and of course it makes you laugh too.  So from the earliest age we experience laughter in this social context. Tragically, people often say they get less ticklish with age.

What brain regions are involved in laughter?

When you listen to people making nonverbal expressions of emotion like screams, and laughs, and cheers, you experience activation in all different parts of your brain because you’re hearing a complex auditory stimulus.  What’s interesting about laughter is the involvement of the “mirror brain” systems. These are involved both in the production of a behavior and its perception. So the same parts that you use when your face registers an emotional expression, like a wrinkled nose for disgust or a smile for delight, are also used when you hear someone make a corresponding sound, such as “bleh!” or a laugh.  There’s more activation of the mirror system for laughter than there is for, say, disgust.  Now, disgust is an amazingly contagious emotion.  When you hear someone going “Bleh, argh, yuck,” you start feeling sick pretty quickly. But disgust doesn’t recruit the mirror system in the same way that laughter does. And I think that’s because, going back to being tickled abundantly as infants, we have a very well-learned response to laugh and to have people laugh with us. So laughter has a strong element of behavioral contagion.

You laugh, and everyone else laughs, and that makes you laugh harder—

That’s the whole principle of laughter yoga. You get a room full of people to start going “Ha ha ha, ho ho ho,” just making ridiculously posed laughs.  And by the end of it people are just screaming with real mirth. It’s very important for humans as social animals to synchronize and coordinate behaviors with other people, and laughter is a prime example of that. We’re good at inducing it in others, and we’re receptive to being induced ourselves.

A little too good, sometimes. A lot of the laughter you hear in conversation just sounds fake.

One of the things we’ve been looking at is the difference between genuine laughter, the kind you make when you absolutely can’t help but laugh, and posed laughter, the sort that happens when you’re doing it deliberately. We put people in a scanner and had them listen to real laughter and posed laughter. We found that the nervous system is equally activated by both. But when we asked the test subjects to tell us which was which, we found that the more someone had recruited the mirror system when they were listening, the better they were at telling the real from posed laughter.  So there’s some actual value to laughing when you hear other people laugh. It helps you understand the social significance of their laughter.

Why is it that posed laughter can be so annoying?

The most important things in our environment is other humans.  And we’re continuously using our perception and our sense of how affiliated we are with other human beings to understand their behavior. If the laughter doesn’t seem to fit with our sense of what that relationship is, the mismatch is quite glaring.  And it’s very hard to mirror back. There’s something sort of pandering about posed laughter. It’s signaling “I’m not threatening you.” It’s almost a subservient kind of noise. It seems to happen quite a lot—probably most human laughter is just trying to induce the other person to like you. Now the opposite of that, which is when you are with people with whom you are affiliated in some way and have some level of empathy—the Italians use the word simpatico—then you experience the kind of laughter you don’t notice.  It just flows.

What can the average person take from your research and apply in their daily lives?

Our results indicate that the more practice you get, the more that you prime yourself, the easier you’ll find it to laugh and the better you’ll understand laughter. So disinhibit yourself. If you find that difficult, laughter workshops and laughter yoga classes are becoming more popular. Some people are absolutely evangelical about it.  When we recorded our subjects laughing, one of our post-docs said afterward that she’d come in that morning in a filthy mood, feeling just dreadful. And she left with a spring in her step, just because she’d had an opportunity to laugh.



2 thoughts on “Laughter’s Secret Purpose”

  1. Looks like some editorial commentary slipped in at the section on “What brain regions are involved in laughter?”

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