SHANKAR VEDANTAM, HOST: This is HIDDEN BRAIN. I'm Shankar Vedantam. When Sophie Scott was about 6, she came across her parents doing something very strange. They were rolling around laughing.SOPHIE SCOTT: In my memory, they were actually on the floor of the living room absolutely overcome with laughter.(LAUGHTER)SCOTT: They'd laughed so much they could literally do nothing else but laugh.UNIDENTIFIED PERSON #1: Oh, my gosh.(LAUGHTER)VEDANTAM: What had got them laughing was a song.SCOTT: A comedy song about what people were not was supposed to do in toilets on trains. It's set to quite a famous piece of music, and it goes (singing) customers will please refrain from passing water while the train...(SOUNDBITE OF SONG, "HUMORESQUE")OSCAR BRAND: (Singing) Is in the station. Darling, I love you. We encourage constipation while the train is in the station.SCOTT: And as they remembered more and more of it, they got more and more helpless.(SOUNDBITE OF SONG, "HUMORESQUE")BRAND: (Singing) If you wish to pass the water, kindly call the pullman porter. He'll place a vessel in the vestibule.(LAUGHTER)VEDANTAM: Now, maybe you are thinking, wait, this song isn't that funny.(SOUNDBITE OF SONG, "HUMORESQUE")BRAND: (Singing) Try the platform in the rear.VEDANTAM: But we've all been there, right? You're with a friend. They say something ridiculous...(LAUGHTER)VEDANTAM: ...And then your laughter...(LAUGHTER)VEDANTAM: ...Triggers their laughter.UNIDENTIFIED PERSON #1: (Laughter) Oh, my God.VEDANTAM: Sophie didn't know then that laughter would play a big role in her life. But today, she thinks about laughter a lot. She's a neuroscientist who studies the science of laughter. So she often thinks back to that moment with her parents back when she was 6.SCOTT: Years and years later, my father was mortally ill. I mean, he thought he was dying. We all thought he was dying. And the doctors didn't know what to do, and it was - we were just sitting around waiting for something to happen. And my father suddenly said, we've laughed a lot, haven't we? And I said, yes, we have. And I thought, you know, what a strange thing to say. And it was years later when I was doing a lot more work on laughter I thought, now, he was right, you know? If you can look back on a life where you've shared a lot of laughter with the people around you, with the people that you care about, those are not times wasted. Those are the good times. Those are the times that really matter. And letting yourself value that rather than thinking it's a silly or a trivial waste of everyone's time, that you should be spending your time being serious, you know, it is worth taking - worth taking the laughter seriously.VEDANTAM: Today, we take laughter seriously. Sophie Scott tells us about the varied shades of laughter from politeness...(LAUGHTER)VEDANTAM: ...To discomfort...UNIDENTIFIED PERSON #2: Oh (laughter).VEDANTAM: ...To delight.(LAUGHTER)VEDANTAM: Decoding the meaning of laughter - this week on HIDDEN BRAIN.(SOUNDBITE OF MUSIC)VEDANTAM: Sophie Scott is a neuroscientist at University College London. She studies laughter, how laughter is processed by the brain and the role it plays in shaping social connection. Sophie, welcome to HIDDEN BRAIN.SCOTT: Hi.VEDANTAM: I want to play you a clip of a very strange sound, Sophie.(LAUGHTER)SCOTT: (Laughter) I can't lie to you. I don't think I've ever heard that before. (Laughter) I'm assuming that is someone laughing, though it was - or maybe not. I mean, one of the points about laughter is it's more like an animal call than it is like any human speech. So it can be extremely similar between humans and other animals.VEDANTAM: That's what I wanted to get to. This is a clip of someone laughing uncontrollably, but it's almost as if another creature has taken this person over. You know, all the polish and the culture have gone out the window, and you get these strange sounds, these almost animalistic sounds.SCOTT: It really is. And we actually - in our normal day-to-day behavior, humans have a lot of control over the things that we do and the sounds that we make. And actually that's one of the things that's unusual about humans. We don't just react flexibly to our environment, but we can modulate how we respond. A lot of other animals, particularly for vocalizations, their vocalizations are highly reflexive. Something happens, and they make the sound. Something triggers the sound, they make the sound. And we have a handful of sounds that we make that are from this more kind of reflexive, involuntary route. And it can be quite startling when they come out of you.(SOUNDBITE OF MUSIC)VEDANTAM: Sounds like weeping, grunting and gasps of surprise.SCOTT: A few weeks ago, I was doing a radio recording, and unexpectedly, we were in a chemistry lab, but there was an explosion.(SOUNDBITE OF ARCHIVED RECORDING)UNIDENTIFIED PERSON #3: Let's just drop it in and see.SCOTT: And on tape, I made a proper kind of surprised oh sound.(SOUNDBITE OF ARCHIVED RECORDING)SCOTT: Oh (laughter) that was an involuntary vocalization then. I don't know if you noticed. I was not hoping to make cries...Because I was actually a little bit startled. And I, you know, thought, oh, that's really irritating. I wish I hadn't done that. But it was completely involuntary. And laughter can be like that as well. It can just feel like it's issuing forth from us. And we can make sounds when we're laughing like that that probably, all other things being equal, we'd probably prefer not to make. It can be extremely, well, very animal. And it is animal. It's linking us. It's exactly the same way that other animals make sounds.(SOUNDBITE OF ANIMAL NOISE)VEDANTAM: Sophie was drawn to studying laughter because she was interested in how humans express emotions. Most of the previous work on the subject had focused on visual cues. Sophie asked, what about sounds?SCOTT: I got into laughter by being interested in nonverbal vocalizations, so something like me going oh when I'm surprised or screaming in terror. And I was working with those because we were interested in how humans recognize emotions. And pretty much, all the work on that is done with photographs of faces following in the, you know, beautiful work of people like Paul Ekman. And I was trying to come up with auditory, vocal versions of those. So I was trying to steer away from emotional speech because the faces didn't have any verbal content to them. And it was looking at those and then starting to look at different kinds of expressions that may be more positive emotions as well as negative emotions, like fear and anger, is what actually led me to laughter.So I never set out to study laughter. I was interested in these nonverbal sounds. And they can be highly involuntary. And in fact, when we make them, they are much more like animal calls than they are like speech. We don't do any of the fancy detailed movements of the lips and the jaw and the teeth and the tongue that we do when we're talking. We in fact - often, the mouth doesn't do much at all. You might pull a facial expression and then you just squeeze air out through the voicebox.(LAUGHTER)VEDANTAM: Is there evidence that other animals laugh like humans laugh?SCOTT: There is evidence that other animals laugh. So it's actually very easy to see it in other apes. In fact, Charles Darwin wrote quite a lot about this. Ape laughter is very, very similar to - well, we're apes, so, you know, non-human ape laughter is very similar to human laughter. So if you were to hear a chimp laughing...(SOUNDBITE OF CHIMP LAUGHTER)SCOTT: ...It looks really like laughter. So you see, it's very, very visibly similar to human laughter. But there is also laughter-like vocalizations that have been described in other animals that aren't apes and are sort of somewhat further removed from us in evolutionary terms. So laughter has been - well, laughter-like behavior has been described by Panksepp, the late neuroscientist, and he was working with rats. And he noticed that rats make a very distinct vocalization when they're playing with each other. And they wondered if that was something like laughter because laughter is strongly associated with play in apes. And so they started tickling the rats, which is when you also find laughter in apes, and the rats made the same sound when they're tickled.VEDANTAM: They actually got rats in a cage and leaned in and tickled them literally?SCOTT: (Laughter) Yes, yes. And if you - what they find is that - really important stuff. So rats definitely produce this vocalization when they're playing and when they're being tickled. And if they want you to tickle them, they will make the sound.(SOUNDBITE OF RATS CHIRPING)SCOTT: And if they see you come into the lab and you normally tickle them, they make the sounds.(SOUNDBITE OF RATS CHIRPING)VEDANTAM: These sounds, by the way, are so high-pitched, they normally can't be heard by the human ear.(SOUNDBITE OF RATS CHIRPING)VEDANTAM: You have to manipulate the recording to hear how rats respond to tickling.SCOTT: So it really does seem to be a kind of an invitation to play, as Panksepp calls it, but it may not just be a trivial thing. So, for example, you can do experiments with rats you can't do with humans. He found that the more you tickle a baby rat when it's a baby, the more that the rat will laugh when it's tickled as an adult, so you can potentiate laughter, the rats tell us. And some more recent work with laughter and rats is it's shown that if you remove the vocal cords of the voicebox from rats so they can't make any vocal sounds, if you let those rats grow up and get - you know, they'll - they interact with other rats. They'll play with other rats. But they are more likely to be bitten if they play with another rat because one of the things that their laughter vocalization is doing when the rats play with each other is it's signifying we're still playing. And it helps you manage that interaction because the same behavior that happens during play could just spill over into aggression. And if you can't laugh, the data suggests from the rats, actually that's harder for you to manage.VEDANTAM: I want to play you one more clip that shows uncontrollable laughter and how strange it is. It's a clip that I think you're familiar with, Sophie. Two BBC commentators are talking about a cricket game, and I'm going to play the clip at a slightly extended version of the clip because it's worth hearing how this develops.(SOUNDBITE OF ARCHIVED RECORDING)JONATHAN AGNEW: And he knew exactly what was going to happen. He tried to step over the stumps and just flicked a bail with his right hand.BRIAN JOHNSTON: He tried to do the splits over it, and unfortunately, the inner part of his thigh must have just removed the bail.AGNEW: Just didn't quite get his leg over.JOHNSTON: Anyhow, he did very well indeed, batting 131 minutes and hit three fours. And then we had Lewis (ph) playing extremely well for his 47 not out (ph). Aggers, do stop it. Lawrence (ph), always entertaining, batting for 35 (laughter) 35 minutes. Hit a four over the wicket-keepers.(LAUGHTER)JOHNSTON: Aggers, for goodness sake, stop it.AGNEW: There's Lawrence, who I've heard is playing extremely well.(LAUGHTER)JOHNSTON: He hit a four over the wicket-keeper's head but he was out (unintelligible).VEDANTAM: So, Sophie, these are these are professional broadcasters on live radio. It's almost as if something has taken over.SCOTT: It is. So the BBC very specifically gets cross with particularly news broadcasters and sports broadcasters, people who are doing things live on BBC Radio. The BBC does not like them to laugh or show emotion. They call it breaking. And they knew they were going to get in trouble. They really didn't want to - you know, there's - the situation is they don't want to be laughing. But when it's got its claws in you, it will happen.There's something unbelievably powerful about the way laughter can overwhelm our motor system. So it stops us breathing. It stops us talking. You heard. They were completely unable to keep speaking. And all they have to do is talk on the radio. It's what they do for a living. And the laughter's stopping them doing all that. And it just comes along and basically just - you have to just power through it. And right towards the end there, you heard Brian Johnston's voice. He gets - at times, he can't talk at all. At other times, he's going (imitating Brian Johnston) he hit a four over the wicket-keeper's head.Because he's trying to talk through the laughter. That's a very, very powerful thing to happen. To actually render someone unable to speak is extraordinary.VEDANTAM: You know, there's two things that you said that jumped out at me. One is that, you know, so much of this was social. In other words, one of the commentators was telling the other one please stop because if you don't stop, then I can't stop. And I've had that experience, too, where you're laughing uncontrollably, and you're telling the person next to you you need to stop because if you don't stop, I don't have any control. So that's one interesting point. But the second interesting point is, why would evolution create something in us that would essentially cut us off from being able to breathe?SCOTT: It's very interesting. So if you - going back to your point about the social and the contagion so that - in some ways, that is a pure example of behavioral contagion because they're both only laughing because the other one is laughing. Interestingly, if they didn't know each other, they'd be much less likely to share laughter that way because you don't catch laughter from someone you don't know or don't like in the same way as you catch from someone you know and maybe someone you like. And I think that's the other reason because the BBC likes playing that clip now, and I think that's because we know 25 years later that if those two men had hated each other, they would not have been laughing that way. Do you know what I mean? You're hearing something real actually there. That's a completely unmoderated joy in each other's company that is overruling everything else.VEDANTAM: You know, I had a friend who visited the United States some time ago, and this friend didn't speak English, but she was listening to a program that used to run on public radio called Car Talk.(SOUNDBITE OF RADIO SHOW, "CAR TALK")RAY MAGLIOZZI: Hello, and welcome to Car Talk from National Public Radio with us, Click and Clack, the Tappet Brothers.VEDANTAM: It essentially had these two guys talking about car repair, but really it was about, you know, the relationship between them. And there would be these extended sections of the show where the two of them essentially would be in hysterical laughter.(SOUNDBITE OF RADIO SHOW, "CAR TALK")MAGLIOZZI: I have the car for you, Steve (ph).STEVE: I'm ready.MAGLIOZZI: An El Camino.(LAUGHTER)VEDANTAM: They just could not stop laughing at each other and at themselves. And my friend, who did not speak English, loved the show.(SOUNDBITE OF RADIO SHOW, "CAR TALK")MAGLIOZZI: Yeah, you ever notice when you say to a Volvo owner, oh, it's going to be a thousand bucks, they'll say, oh, only a thousand.TOM MAGLIOZZI: A thou.(LAUGHTER)VEDANTAM: Because she said there's something about listening to these two people laugh, you know, out-of-control laughter, that made her happy. There's something the language - that laughter communicates that even perhaps goes beyond language.SCOTT: It does. And I think part of it is because, you know, as your friend who's experiencing it, it is a universal emotion. So wherever you go in the world, you'll encounter laughter. It has at its heart the same meaning. It's very truthful, and it's telling you something very positive. And that's always a sort of wonderful thing to encounter.(SOUNDBITE OF MUSIC)VEDANTAM: Coming up - what makes us laugh.(SOUNDBITE OF PAPER TEARING, LAUGHTER)VEDANTAM: This is HIDDEN BRAIN. I'm Shankar Vedantam. Here's how it usually goes. You're working from home, and you call in by conference call for the morning meeting.UNIDENTIFIED PERSON #4: Welcome. Please enter your access...VEDANTAM: Everyone is happily chatting around the table.UNIDENTIFIED PERSON #5: Yeah, exactly...VEDANTAM: But as you sit there on mute...(CROSSTALK)VEDANTAM: ...It all sounds very unfunny.(LAUGHTER)VEDANTAM: You can't believe how much fun people seem to be having...UNIDENTIFIED PERSON #6: Yes, that one.VEDANTAM: ...Talking about nothing. Then someone starts to laugh.(LAUGHTER)VEDANTAM: Soon, everyone's laughing...UNIDENTIFIED PERSON #5: (Laughter) Yeah, exactly.UNIDENTIFIED PERSON #7: I've been watching a lot.VEDANTAM: ...Except for you, silently listening on the phone. You're not even cracking a smile. Forget about laughing. You wonder, when did this conversation become so hilarious? What am I missing? Well, it turns out laughter often isn't about responding to humor. It's an insight based on the work of laughter researcher Robert Provine. Here's neuroscientist Sophie Scott.SCOTT: I thought that humor was the main thing that drove laughter. That's what I called laughter for years when I was first working with it. I called it amusement so I thought, oh, it's an expression of amusement. And then I read Robert Provine's work. And Robert Provine, he's very clear. Although we think we laugh at humor and jokes, our lay belief - our lay psychology, which I shared, is that it's a reaction to humor. Most of the laughter that we produce is purely social in its origins. We laugh when we're with other people. We're primed to laugh when we are with other people more than if we're on our own. And other social factors like do we know those people, do we like those people, that will feed into that.VEDANTAM: I understand some of the earlier research found that almost 80, 90 percent of the time, you know, laughter followed phrases like, you know, I'll see you later or it was nice meeting you, things that were completely unfunny.SCOTT: Exactly. And it's because we laugh - we laugh to show - well, we laugh to make and maintain social bonds. I mean, laughter can be a really efficient way of just smoothing over a social interaction with somebody. But when we're with people that we're having a more enduring conversation with, their laughter is as much to do with showing agreement, showing understanding, showing recognition, you know, saying go on. Yes, I think I remember this, but carry on telling me. You know, it's got all this kind of nuanced meaning.And Provine has even found that at any one point in time, the person who laughs most in a conversation is the person who's talking, which really does suggest that it's being used in a very communicative way.VEDANTAM: So I want to talk about the social nature of laughter in the context of laugh tracks. So this is an example of the media in some ways hijacking the way laughter operates in our brains. I want to play you a clip from the TV show "Seinfeld."(SOUNDBITE OF TV SHOW, "SEINFELD")KIERAN MULRONEY: (As Timmy) What are you doing?(LAUGHTER)JASON ALEXANDER: (As George) What?MULRONEY: (As Timmy) Did you just double-dip that chip?ALEXANDER: (As George) Excuse me?MULRONEY: (As Timmy) You double-dipped the chip.ALEXANDER: (As George) Double-dipped? What are you talking about?MULRONEY: (As Timmy) You dipped the chip, you took a bite, and you dipped again.(LAUGHTER)VEDANTAM: So what do laugh tracks tell us about the social nature of laughter, Sophie?SCOTT: Well, the interesting story of laugh tracks is they became a necessity when we started to be able to record and broadcast programs that we were hoping people would find funny because the natural home of laughter is in social settings. And in theatrical and performance environments, people would be laughing - they'd laugh at the theater. They'd laugh at musicals. They'd laugh at people doing performance stuff, but that was always be a shared experience. You were in an audience and you were a part of a group of people laughing. And as soon as you go down to something that's being broadcast, people don't necessarily get all those cues. So suddenly, they were finding that people weren't necessarily hearing a radio program as sounding funny because there were no cues to help you hear that.So a solution to this problem of people not necessarily finding things funny if there wasn't the sound of laughter but also studio laughter sometimes being hard to control, Charles Douglass, who was a sound engineer, invented a - sort of a laugh box where he had recordings of laughter...(LAUGHTER)SCOTT: ...Which he could mix together and drop in. And then this became very easily controlled because you then have this technique for being able to have exactly as much laughter as you want at the time that you want it without having to worry about the empty silences or uncontrollable studio laughter.VEDANTAM: And it's kind of incredible, isn't it, which is, in some ways, the studio is manipulating when you laugh, not with the jokes but with the laugh machine.SCOTT: I suppose in a sense they always were. And it is interesting that if you look at - because some programs carried on making a point of saying, you know, this is filmed in front of a live studio audience. So "Seinfeld" is an example. "Cheers," "Friends," you know, they would make it quite a big deal that you knew this thing was being performed in front of an audience. And in fact, "Friends" would - they would do a whole rehearsal with a live audience there and look at when people laughed and then go away and rework lines so you could maximize the relationships between what was being said and when the laughter happened. So they were, you know, almost being scientists about it, which is as manipulative. It's all trying to control the audience laughter because it's considered to be something that makes it sound better.And I think one of the things that's interesting about studio laughter or canned laughter, as people started calling the, you know, an extra recording that's been dropped in, is that one of them started to be very - considered to be very, you know, not quite the thing, so we became a bit snobbish about canned laughter. In the U.K., I think "M.A.S.H" was famously shown without canned laughter. In the U.S., it was.(SOUNDBITE OF TV SHOW, "M.A.S.H")LORETTA SWIT: (As Major Margaret Houlihan) I need my things.GARY BURGHOFF: (As Corporal Walter O'Reilly) All right, yeah. I packed your toothbrush, your jammies and one of your slingshots.SWIT: (As Major Margaret Houlihan) You jerkface (ph). That's my garter belt.SCOTT: It has quite a different experience watching the two.(SOUNDBITE OF TV SHOW, "M.A.S.H")SWIT: (As Major Margaret Houlihan) I need my things.BURGHOFF: (As Corporal Walter O'Reilly) All right, yeah. I packed your toothbrush, your jammies, and one of your slingshots.SWIT: (As Major Margaret Houlihan) You jerkface. That's my garter belt.(LAUGHTER)SCOTT: It sort of became a bit of a cultural thing about whether or not you had laughter on it at all, so there became more of a fashion for comedy to not need that. So things like "The Office" in the U.K. didn't have a laughter track of any kind and would have looked down a little bit I suspect on programs that felt they needed to. So, you know, it's definitely - it's not just the laughter and whether the laughter is live or canned. It's to do with your view of the sort of programs that might need laughter, or do you think they need laughter? You know, our understanding of laugh tracks gets a bit nuanced.VEDANTAM: You said a second ago that people can be snobbish about laugh tracks, but people are also in some way snobbish about laughter. We think of one kind of laughter as real and one kind of laughter as fake. So the social greeting laughter we think of as fake and we think about the rolling on the floor helpless with laughter as real. Is social laughter fake and spontaneous laughter real?SCOTT: Well, at one level, they are. And, you know, it's the case that the spontaneous laughter, the kind of stuff you cannot stop doing, is definitely different to laughter that at some level, has got a performative or communicative element. And it's - I must admit. Sometimes, I call them real and fake laughter just because it's very easy. People know what I mean. But I'm very well aware that when you call it fake, you are valencing it. You're making it sound like it's a bad thing. And of course, most of the time - the vast majority of the time, it's not a bad thing at all. It's a great thing.You recognize the meaning of laughter that a friend gives you or someone gives you. It has a positive aspect to it, and the fact that somebody is giving you their laughter - the fact that they're actually choosing to produce that laughter for you, we've found that people actually seem to be marking their communicative laughter. For example, in the U.K., it can quite often be very nasal, a (imitating laughter) sound to it. But you couldn't do that if you were laughing spontaneously, and that really does suggest that people are going out of their way to say, look; I'm giving this to you. This is laughter I'm trying to produce for you.(SOUNDBITE OF MUSIC)SCOTT: In an interaction where you like the person, you have a good relationship with that person, you know what that means and you take it. I think the situations where we get upset by laughter that sounds put-on is when we don't know those people. If you've ever been on a train with a load of friends who all seem to be sitting there going ha, ha, ha, ha and you think oh, goodness me, they're all faking that laughter - because if you're one of the friends, you wouldn't care at all - you know, it's because you're not part of that group. You are isolated from it, and you're hearing the performative-ness rather than the warmth.And also - I tried - this isn't science, but if you think about - if there's somebody you know who laughs really inappropriately, who has an irritating laugh, if you think about that - most people can think of someone - and I've never found anyone who really likes that person. (Laughter) So actually - so I have a relative who's always - I've always thought, oh, they laugh really inappropriately. And so working with the laughter, I've realized it's because there's nothing inappropriate about their laughter. It's just I don't join in with it because I don't really like them. And it's me withholding my laughter that I'm experiencing as them doing something wrong and their laughter being irritating. But it's not. It's me that's being different.VEDANTAM: So that's an interesting insight because what you're saying is that it's your affection or lack of affection that prompts you - prompts you to see that laughter as being, you know, inappropriate or appropriate or enjoyable. So it's really we think - in the conventional way, we think someone has an inappropriate laugh, I don't like it. But really, you don't like them, and that's why you think their laugh is inappropriate.SCOTT: I think so. And I think actually - and this is, you know, this is - this is a hypothesis. Let's be generous and call it a hypothesis. I don't have any data to back this up, but I think we do that quite a lot with laughter because we do the opposite as well. If somebody makes us laugh, we will say, oh, they're hilarious. They've got a great sense of humor. They make us laugh. What they mean is I really like them. I really like them, and I laugh when I'm around them so that they will know that I like them, and maybe they'll like me, too. You know, it's a - it's a - but we attribute it to other people. We attribute our laughter to other people, or our lack of laughter, we attribute to other people.(SOUNDBITE OF MUSIC)VEDANTAM: Laughter, in other words, can tell us a lot about relationships between people. It's a signaling device. But how are we so good at decoding what laughter means?Sophie had a hunch. She conducted an experiment to show that the brain actually processes different kinds of laughter differently. She recruited a couple of people to join her on her London campus. She invited them into a strange, little hut. Inside this hut was a windowless room where all the surfaces were covered with wedges of foam, and the only things in the room were a pair of speakers, a chair and a computer monitor that was bolted to the wall. Once the door was closed, you could finally encounter true silence, an experience few people could tolerate for more than a few minutes. Inside this tiny, joyless chamber, Sophie recorded herself and the two other people laughing.(LAUGHTER)SCOTT: It is a weird little space because it's perfect for making absolutely beautiful recordings, but it's sort of antithetical to getting people laughing.VEDANTAM: She used a few tricks. She started slow.SCOTT: We spent a long time warming them up before we tried to put anyone in the anechoic chamber and make - on their own to laugh. And then we'd make sure that the person in the anechoic chamber, when they did, you know, when they were laughing, we kind of throw them in there, close the door and start recording.VEDANTAM: Once she had her beautiful recordings of different kinds of laughter, she played these clips for volunteers as they lay inside a brain scanning machine. Her question - would the brain register the difference between laughter that was polite and laughter that was spontaneous?SCOTT: And what we find is people hear laughter and they start trying to work out what it means. And if the laughter is spontaneous, you get a different pattern of neural activation than if the laughter is, at some level, being intentionally produced. And in fact, that is reflected in the brain activation you see.VEDANTAM: When the volunteers heard uncontrolled belly laughs...(LAUGHTER)VEDANTAM: ...The brain scans showed they focused on the sound of the laughter. But when they heard the recordings of the polite chuckles...(LAUGHTER)VEDANTAM: ...The brain scans suggested the volunteers were thinking. They were asking the question, what's really going on here? For Sophie, the experiment confirmed that laughter always means something. It's a code we're always trying to decipher.(SOUNDBITE OF MUSIC)VEDANTAM: This might be why most of us can tell the difference between laughter among friends...(LAUGHTER)VEDANTAM: ...And laughter among strangers.(LAUGHTER)VEDANTAM: It turns out, you don't need to know anything about the two people laughing. You don't even need to see them. All you need to do is hear them laugh for one second. Some years ago, the cognitive scientist Greg Bryant at UCLA recorded pairs of friends and pairs of strangers having a conversation. He pulled out all the moments when they laughed, and then cut the laughter into tiny bursts that lasted just a second. He and his colleagues played these tiny little laughter clips for nearly a thousand people from 24 societies all over the world. The researchers asked the volunteers if they could tell whether the people laughing were friends or strangers. Why don't you see if you can tell the difference? Here's one set of three laughs strung together.(LAUGHTER)VEDANTAM: And here's another.(LAUGHTER)VEDANTAM: If you guessed that the first clip was strangers and the second clip was friends, you're right. Most people in the study got it right. People all over the world could hear the difference.SCOTT: And it makes sense because we don't laugh with just anybody. You know, we - laughter is a very good index of how we feel about the people that we're with. And it's not like we're laughing or we're not laughing and that's the only difference. You can have much more kind of performative - you know, if I bump into someone in the street and we both laugh and say we're OK, I'm not going to stand there going that laughter wasn't very intense because I know what it means. You know, it was doing its job of sorting out a slightly difficult situation whereas with a friend, the laughter is likely to be much warmer because it needs to be, and it can be. And it's an index, actually, of how those friends feel about each other. So I think it's interesting that we're so alive to it. Like, we really notice it. And as I say, I think that's because it's an incredibly important social signal, and we recognize its emotional meaning.(SOUNDBITE OF MUSIC)VEDANTAM: This emotional meaning is usually positive but not always. When we come back - the connection between laughter and power.(SOUNDBITE OF MUSIC)VEDANTAM: During the 2018 Supreme Court confirmation hearing for then-Judge Brett Kavanaugh, there was a moment when the role of laughter took center stage. California psychologist Christine Blasey Ford had accused Kavanaugh of sexually assaulting her when they were both teenagers in Maryland. She said that Kavanaugh had leaped on top of her and tried to disrobe her at a party while a friend watched. Kavanaugh strenuously denied the allegations. The U.S. Senate invited Christine Blasey Ford to testify, and Senator Patrick Leahy asked her about the allegation.(SOUNDBITE OF ARCHIVED RECORDING)PATRICK LEAHY: What is the strongest memory you have, the strongest memory of the incident, something that you cannot forget? Take whatever time you need.CHRISTINE BLASEY FORD: Indelible in the hippocampus is the laughter, the uproarious laughter between the two, and they're having fun at my expense.LEAHY: You've never forgotten that laughter. You've never forgotten them laughing at you.FORD: They were laughing with each other.LEAHY: And you were the object of the laughter.FORD: I was, you know, underneath one of them while the two laughed - two friends having a really good time with one another.VEDANTAM: Sophie, I don't want you to get into the debate over Kavanaugh, but as a researcher who studies laughter, how do you respond to what Christine Ford told the Senate?SCOTT: Well, I mean, it's almost unbearable to listen to, but it's also very recognizable because if you think about laughter as being about making and maintaining social bonds, it has to mean by definition that someone is excluded from that bond. Otherwise, it doesn't mean anything. So we normally dwell on the positive side of that. Look; we're making and maintaining social bonds and that's great. But if you are excluded from that, you're excluded from that laughter, it's awful. And it's awful because we have a very, very strong understanding of what that means. And there's a lot more to this. There's the situation where something terribly serious is happening - from your perspective, something awfully serious is happening - that is being treated as fun by other people.There was a court case in the U.K. recently where a woman's son had been murdered, and in the court, the two young men who were up for his murder were laughing and joking. And she made a statement precisely about this. They can't even take this seriously, you know, that my son's death and they're being - they're going to go to prison for it, and they are still laughing. And I can totally understand why that was almost the worst part of what was going on for her. That's - it's like mocking how little they care about your situation. So it can be very powerful.That kind of distinction, who is laughing at who, who has got a bond with who and who is being excluded from that, can be a very, very marked way of not just excluding somebody from a social group but actually marking them as inferior. And we have this behavior that's being done by the people who are more important, the people who have greater status. They can find something fun and enjoyable because they're the ones with the power.VEDANTAM: And in some ways, laughter is a way to reinforce status, isn't it? I mean, I'm thinking about schools, for example. When you think about bullying in schools, one of the things that happens is if a group of kids is laughing at another kid, the kid who is isolated is - recognizes the experience of being isolated partly by who is laughing at him or her.SCOTT: Absolutely. So again, it's - the same laughter can be incredibly warm, positive, friendly, doing all its work for the people within the social group and then be absolutely awful to the person who's being not only excluded from it but is the target for the laughter. And it's one of the worst sensations. You know, if you realize not only are people laughing and you're nothing to do with it but actually, no, hang on, they're laughing and they're laughing at you, it's just sickening. It's a horrible feeling because it's one of the most basic things we care about as humans. We're social primates. Who we get to hang out with, who talks to us, whose - what social network we're part of, that really matters. And when you get this absolutely clear example not only are you excluded from this group but they would care so little to have you be part of them that they would mark you out as being worthy of being laughed at, it's almost - it's extraordinary.(SOUNDBITE OF MUSIC)VEDANTAM: You can see the power of laughter to bond and the power of laughter to exclude in one of the most famous clips in the news from the last few years. In 2005, celebrity TV host Donald Trump was on his way to film an episode of "Access Hollywood." He was having a casual conversation with Billy Bush, a younger man known for his easy rapport with celebrities. Trump was talking about the woman he was about to meet.(SOUNDBITE OF ARCHIVED RECORDING)PRESIDENT DONALD TRUMP: Yeah, that's her with the gold. I got to use some Tic Tacs just in case I start kissing her.VEDANTAM: Pay attention here to the role that laughter plays in their exchange.(SOUNDBITE OF ARCHIVED RECORDING)TRUMP: You know, I'm automatically attracted to beautiful - I just start kissing them. It's like a magnet. You just kiss.BILLY BUSH: (Laughter).TRUMP: I don't even wait. And when you're a star, they let you do it. You can do anything.BUSH: Whatever you want.TRUMP: Grab them by the [expletive].BUSH: (Laughter).TRUMP: You can do anything.VEDANTAM: Sophie Scott argues that powerful people often use laughter as a way to cover up misdeeds and indiscretions. When they are called out on their behavior, they say they are joking, that it was just a locker room talk.(SOUNDBITE OF ARCHIVED RECORDING)TRUMP: Whoa.BUSH: Yes, the Donald has scored.TRUMP: Whoa.BUSH: (Laughter) Oh, my man. Wait, wait, you got to look at me when...SCOTT: Because we aren't very good at understanding that most of our laughter has nothing to do with humor, we can mistake the fact that people who are laughing in a situation with us aren't laughing because what we said was funny. They're laughing because they like us and they're part of the same group as us. But if you go away from that, you know, if you were to choose to take from that, oh, I'm hilarious, then you could also choose to use that as your defense for somebody else objecting to what was going on there. And it's a very, very common one. Often, I think when people say, oh, you know, it was just locker room chat, it was - I was being funny, what they mean is, you know, I almost don't need to justify myself to you.But I think also it can be - it can kind of conflate difficult - in a difficult way with this notion of power because it is the case that if you look at strongly hierarchical situations, I think there was work with doctors in the U.K. where the senior doctor will have a very different sort of social status than the junior doctors in his or her group. And there was data showing that the junior doctors would laugh at something the senior doctor said and the senior doctor would very, very rarely laugh at something the junior doctor said. Now, that's normally taken to mean that people find the stuff funnier if it's produced by the senior person. I think it's also as likely that the junior people are trying to make themselves liked by the senior person by giving them the laughter.You know, it's something we will actively try and use around people. But it does mean that bosses who might have got used to people laughing at what they say, them not realizing it's because of who they are rather than what they're saying, may find themselves in a situation where they have said something genuinely offensive. And when they get called on it, they can't - you know, they - well, no, it was just banter. I was just being hilarious. But they were simply straight up offensive.(SOUNDBITE OF MUSIC)VEDANTAM: Laughter can also be used by the weak to hold the powerful to account. Historians talk about the role of the court jester, often the only one who could speak truth to power, usually through a laugh. Even in countries with authoritarian regimes, laughter can be a sly way to undermine leaders and register discontent. I ask Sophie if laughter could be the weapon of the weak.SCOTT: It can just be a straightforward weapon. So to be clear, it doesn't only have to be used by the weak, but it can work very well. So laughter can be a very good way of - rather than just getting angry about somebody, pointing out, you know, enormous shortcomings in their statements or their behavior in a way that makes people laugh sort of - because they are signalling kind of playful intent and they're also clearly mocking them, you are excluding them and laughing at them, sometimes - there was a U.K. prime minister, John Major, who never really recovered from some journalist spotting when they were on the campaign trail with him that he tucked his shirt into his underpants. And you could sort of see it through his - you know, if you got very close to him. And they just became relentless. Now, it was by no means his worst crime as a prime minister, as a political person, but it was like the thread that was easily pulled at, and everything kind of fell from there. You know, it was absolutely relentless how that was run with.(SOUNDBITE OF MUSIC)VEDANTAM: Laughter can also be used to hold other people at a distance. In our current politics, both liberals and conservatives love to mock each other. It's a way of not having to listen to people you disagree with. Laughter becomes a weapon to solidify the distaste that each tribe has for the other.(SOUNDBITE OF ARCHIVED RECORDING)TRUMP: The elite - why are they elite? I have a much better apartment than they do.(LAUGHTER, CHEERING)TRUMP: I'm smarter than they are. I'm richer than they are.(SOUNDBITE OF TV SHOW, "LAST WEEK TONIGHT WITH JOHN OLIVER")JOHN OLIVER: Because it turns out the name Trump was not always his family's name. One biographer found that a prescient ancestor had changed it from - and this is true - Drumpf. Yes, [expletive] Drumpf.SCOTT: It's grouping writ large. You know, these big social groups - you can sort of see it in the U.K. around Brexit with both sides trying to paint the other as ridiculous and to better or less, you know, success be funny about it. You're using it to mark the commonality with a group of people you share something with as well as your difference from and sort of separation from and the ridiculousness of that other group.VEDANTAM: We've talked a lot about your research and your ideas, but I understand that for the past few years, you also - been a stand-up comedian yourself. Do you remember how you felt the first time you got a really big laugh?SCOTT: I can tell you how I felt before then. I don't think I've ever been so nervous...VEDANTAM: (Laughter).SCOTT: ...Not since my exams when I was at school. I mean, I literally at one point locked myself in the toilet and thought, I could just stay in here. You know, I don't have to come out ever. And the first time I got a laugh - and it wasn't a laugh I was expecting. It wasn't on a line that I thought was funny. I thought oh, it's - you know, I can see light at the end of the tunnel. You know, I'm going to get through this.But the bit I really remember is that when you finish, the - and in stand-up normally in the U.K., there's an emcee who comes on and claps the - you know, and the guy came - I left the stage, and this guy came out and went, ladies and gentlemen, Sophie. And everyone was clapping, and I was like, yes.(SOUNDBITE OF ARCHIVED RECORDING)UNIDENTIFIED PERSON #8: Sophie.(CHEERING, APPLAUSE)SCOTT: People can carry on doing this for as long as they wish to. This is pure hits of dopamine to my nucleus accumbens, you know? Perfect. And then really my next coherent thought was, I want to do that again, and I want to it better. I want to learn how to do this.(SOUNDBITE OF ARCHIVED RECORDING)SCOTT: It's very hard to say this without sounding like you're - I don't know - the undead, but I like brains. And I work with brains. And I'm very lucky 'cause I get to use a technique called functional magnetic...SCOTT: Because I only did it in the first place as a professional jealousy. I mean, I hadn't - I had no plans to set out and get into stand-up comedy until I tried it, and then I wanted to get better at it. I wanted to understand it as a skill.(SOUNDBITE OF ARCHIVED RECORDING)SCOTT: So when you start laughing, it stops you breathing. It stops you talking. It's just squeezing air out of you. It is trying to kill you. It's a relatively dangerous activity, and it can be...'Cause no one is fooled when they see me. You know, no one's thinking, oh, who's this upcoming young comedian? They know I'm a scientist. They know I'm an academic. You know, it's not - I'm not presenting myself as anything other than that. But what I try and do is I take real science, and I take stories, things that have happened to me or my family, and I try to turn that into a short, informative but hilarious set.But what I quite often do is actually take examples of things that have been upsetting. So I once got picked on by some teenage boys at Ipswich railway station, and it was horrible. And they were all laughing at me, and it was really nasty. It was really, really unpleasant, and I turned that into a stand-up act.(SOUNDBITE OF ARCHIVED RECORDING)SCOTT: So like, one minute I'm perfectly happy going home. And now there are a group of teenage boys laughing at me because I looked the wrong way. And you think, oh, this is an interesting situation, isn't it? Scientifically, what's going on here? Well, let's take a think about this. What can science tell us? If we look at the scientific...SCOTT: And that was quite good 'cause I could kind of take off all the different aspects about laughter that I could learn from this interaction. But also it made me feel a lot better about what happened on Ipswich railway station because I had ownership over it, and I got laughed out of it. And every time an audience laughs at that routine, I feel I've got one over on those Ipswich teenagers.(SOUNDBITE OF ARCHIVED RECORDING)SCOTT: What I did instead was I took a scientist's revenge, and I wrote that story up in a peer-reviewed publication.(LAUGHTER)SCOTT: And the next time those teenage boys pick up the December 2014 edition of Trends In Cognitive Neurosciences...(LAUGHTER)SCOTT: ...They'll be laughing on the other sides of their faces. Thank you very much.(CHEERING, APPLAUSE)VEDANTAM: Sophie Scott is a neuroscientist at University College London, where she studies the science of laughter. Sophie, thank you so much for joining me today on HIDDEN BRAIN.SCOTT: Oh, thank you very much. I hugely enjoyed myself.(SOUNDBITE OF MUSIC)VEDANTAM: This episode was produced by Laura Kwerel and edited by Tara Boyle and Camila Vargas Restrepo. Our team includes Jenny Schmidt, Rhaina Cohen, Thomas Lu and Parth Shah.Our unsung hero this week is my colleague Stephen Thompson, who works at NPR Music. Stephen sends out periodic notes announcing guests who are going to perform at the Tiny Desk Concert Series at NPR, and his notes are invariably filled with funny observations about his boss, his Green Bay Packers football team and sunsets. These emails, like the one about eating between 15 and 25 bowls of cereal one Friday night, do something we could all use more often in our lives. They make us laugh. You can hear Stephen for yourself on NPR's Pop Culture Happy Hour podcast.(LAUGHTER)VEDANTAM: I'm Shankar Vedantam. See you next week.SCOTT: 'Cause actually, most people don't really like being tickled. I was doing a talk at the Royal Society a few years ago, and this very elderly, very distinguished member of the Royal Society, fellow of the Royal Society went, I love to be tickled.(LAUGHTER)SCOTT: I am not going to tickle you, sir. That's not most people's reaction.VEDANTAM: Different show, different show, Sophie.(LAUGHTER) Transcript provided by NPR, Copyright NPR.