Friday, July 17, 2009

Apple #397: The Purpose of Laughter

The other day I was walking home after a very nice walk in the woods, and I was approaching a busy intersection. A woman was standing at the corner with some friends, waiting for the light to change, and she laughed. Loudly enough that it echoed across the entire intersection.

It was such a carrying laugh it really struck me, and I suppose because I'd just come out of the woods and had been surrounded by all sorts of nature, I wondered, what is that laughter supposed to communicate? Like, if scientists were studying us as if we were just another animal out in the woods or someplace, what would they write in their scientific papers about what we humans are communicating to each other when we laugh?

  • Laughter, the scientists say, forms social bonds. It's a way of saying to the people around you, I'm a friend, not a foe.
  • During play, even aggressive play, if someone laughs, that signals to the other person, I'm only kidding around, don't take it seriously.
  • The person who hears the laughter experiences a reduction in tension. Specifically, the fight-or-flight response that we get in response to danger is significantly calmed down when we hear someone laugh.
  • One way that scientists know this is by observing other animals who also laugh. That's right, there are other animals who laugh: rats in response to tickling, dogs, chimps, and apes, to name a few.
  • The laughter sounds made by other animals are not as vocalized as ours are. Dogs make a sort of breathless panting when they laugh. Chimp laughter sounds like a handsaw cutting wood. Rats make high-pitched chirping whistles out of range of the human ear.

I wonder if the breathy sounds that other animals make sound anything like this type of breathy laugh.

  • Researchers have observed that if a dog doesn't laugh during play, the other dogs will interpret it as aggressive and they will attack.
Here's proof that dogs know all about tickling. This Great Dane is tickling this baby, to the obvious enjoyment of both dog and baby.

  • Besides signaling I'm only having fun, laughter further develops social bonds through its contagiousness. When we hear someone laughing, we tend to start laughing at the very sound, whether we even know what it's about.
  • If Jane is laughing, and we all start laughing along with Jane, we're all sharing something together and, bing, we've formed a social bond.
  • By the way, the contagiousness of laughter is what's behind all the laugh tracks in TV shows. We are far more likely to laugh when we are in a group than when we are alone (even laughing gas has been shown to be less effective when taken with no one else present), and we are even more likely to laugh if we hear others doing it, too. So when we're watching some TV show all by ourselves and the jokes are pretty lame, we might not laugh at all. But if the show has a laugh track with sounds of lots of people laughing, we are more likely to laugh.
Something about this sound file of a guy laughing makes me laugh.

  • The down side of laughter is that sometimes we use it to laugh at other people. To mock them. This has the effect of excluding people, of telling them by our laughter that they are not as good as us in some way.
  • But I'm willing to wager that most of the time when we laugh at someone else, we're probably doing it in front of a group of others. I am guessing that we are really trying to form a bond with those other people by laughing at that one person we've identified as somehow not good enough. We're trying to say to the other people, "You and I are not like that low-life. We are better than him or her and so we get to laugh together at that person." It's not a happy way of forming a social bond, but it's a social bond regardless.
  • While we might want to do all we can induce other people to laugh, especially if we are TV producers, it is very hard to make someone laugh on command, or even simulate laughter.
Sounds like this is a young girl, and her laughter sounds utterly fake.

  • In fact, laughter is defined as an uncontrollable response. At the same time, it is one whose goal is to form a bond with other people. Which is a pretty strange thing when you think about it. As one astute researcher pointed out, when was the last time you felt overcome by the urge to repeat, "Hello hello hello"?
This explosive laugh sounds like the person was completely overtaken by the need to laugh.

  • We don't make just any sounds when we laugh; we make a series of very specific sounds. Almost always, they are vowel sounds repeated, as in "ha-ha-ha," or "he-he-he." Sometimes we might alter the first or the last vowel sound ("Ho-ha-ha-ha" or "Ha-ha-ha-he"), but rarely do we change up those vowel sounds within the sequence. "Ha-ho-ha-he-ho," for example, seems all wrong and even a little disorienting.
This laugh starts out with a bunch of ha's but then changes to lots of inhalations in a row. But still, it's a repeating pattern rather than an alternating one.

  • We also tend to repeat the vowel sounds at nearly the same time apart from each other. Ha-ha-ha-ha. In fact, one researcher has measured the time in between each "ha" to be an average of 210 milliseconds apart. Any faster (hahahahaha) or especially slower (ha . . . . ha . . . ha . . . ha) and we tend to distrust it.
To me, this woman's laugh sounds genuine at first, but then it seems to be too precise, or too well-spaced, and by the end, I distrust it.

  • We also usually begin laughing loudly and get quieter to the end of the vowel sounds, presumably as we run out of air. If you try to begin softly and get louder, it will feel and sound completely wrong.
  • (I'm noticing that, as I try these variant forms of laughing, the weirdness of it is making me laugh.)
  • (And, while I'm noticing that talking about laughing can induce laughs, the word itself is weird. I've noticed this while typing it so many times for this entry. So I looked it up. Etymologically speaking, it comes from words that look more or less insane:
  1. hlæhhan [Old English]
  2. hlihhan [Germanic]
  3. hlæja [Old Norse]
  4. cachinare [Latin]
  5. kakhati [Sanskrit]
  • These words are all weird looking because they are trying to be onamotapoetic. That is, they are attempts to make words that sound like their meaning, in this case, laughter.)
  • Getting back to my point about how we use laughter, unlike how I've interrupted my own train of thought, we don't usually laugh in the middle of a sentence. If you listen to someone telling a joke to a group of people, you'll notice that 1) the person doing the telling is laughing a lot more than the listeners--signaling that it's a joke and trying to encourage them to laugh; 2) the person doing the telling/laughing will nearly always inject the laughter at the end of a sentence. "So I went to the butcher shop, right? (ha-ha) And standing at the counter, there was this dog. (ha-ha)" Et cetera.
This woman says a sentence and laughs at the end of it -- punctuates it with her laugh.

  • The well-ordered nature of laughter -- you never would have thought that before -- suggests that laughter is a very deeply rooted neurological response. That is, as well as being all about communication and language and culture, it is so fundamentally so that it is physically encoded into our brains in a very specific way.
  • That's part of the uncontrollable response nature of laughter. But another sign that laughter is hard-wired into us is that every single culture of people on earth laughs. We all laugh in response to tickling. (That's called reflex laughter) And, I'm willing to bet, that since we all laugh when we are tickled, we would all recognize when someone is laughing in response to being tickled.
  • I'm going to suggest here to any negotiators who are trying to broker world peace in the midst of hugely tense cross-national talks, that everyone should take a break for a little tickle party. It's something everyone can agree on, it'll get everybody laughing, it'll take all the tension out of the room, and then maybe something could get accomplished.
  • My suggestion isn't so wacky. Various weighty international negotiations, such as those between Reagan & Gorbachev at Geneva or the Middle East peace talks that took place during the Clinton administration, often changed dramatically in tone once someone told a joke. In some cases, it was only after they got each other laughing that they were able to relax enough to reach some kind of agreement.
Another possible tool to break the ice in rocky negotiations could be showing cranky world leaders this video.

They might all start getting on each other's trampolines and yelling at each other like that, though.

This person sounds like she thought something was funny, laughed, thought about it some more and thought it was funny enough to laugh at it again. Which is exactly what I'm doing in response to that video.

  • However, you do have to be careful about telling jokes to people from other countries. Because reflex laughter is the only kind of laughter that is universal. Laughter in response to jokes is very culturally-dependent. If you try to tell a joke to somebody from another culture and you guess wrong at their sense of humor, you might not make them laugh, or worse, you could risk really offending them. So I think my tickling session idea has a far greater chance of success.
  • Or everybody could play a good game of Ha. We used to play this at slumber parties. (For the sake of clarity, I'm going to alternate genders here, but in real life, the slumber parties I went to were not co-ed.)
  • Person 1 lies down on the floor on her back. Person 2 lies down on his back, perpendicular to her, with his head on her stomach. Person 3 lies down on her back, perpendicular again and with her head on his stomach, and so on until everyone is lying down with his or her head on the stomach of someone else and also with someone's head on his or her stomach.
  • Person 1 begins by saying "Ha" a few times. Saying this word will push air out of Person 1's stomach so that Person 2's head starts moving up and down, sort of bouncing. It feels funny, so Person 2 will begin to laugh. That makes Person 3's head bounce up and down so Person 3 begins to laugh, and so on down the chain until everyone is laughing and everyone's head is bouncing.

I'm still thinking about the fact that everyone laughs at being tickled. Everyone. That's pretty powerful.

I wonder how different the world might be today if anyone had ever thought to tickle Hitler.

P.S. for some completely made-up fun based on a true fact (that rats laugh when tickled), stop by the Tickle-easy.

All the laughter .wav files are from Wallace Chafe at UC Santa Barbara's laughter sounds.
Robert R. Provine, "Laughter," American Scientist, Jan-Feb 1996, 38-47.
Kristen Coveleskie, Laughter: the Glue of Humanity? Biology 202, Bryn Mawr College, 2004
Global Oneness, Tanganyika Laughter Epidemic - the Incident
Patricia Milford, "Laughter as Communication: Some Intercultural Implications," Annual Meeting of the International Communication Association, May 1980.
"Tickled apes yield laughter clue," BBC News, June 4, 2009
"Rats 'like a laugh,'" BBC News, May 1, 1998
Encyclopedia Britannica, Laughter
Online Etymology Dictionary, laugh


  1. I had no idea that rats laugh! Although I've seen a guinea pig laugh, so I guess it follows that a rat can.

    Here's the best laugh video I've ever seen. I was in tears by the end.

  2. That dog tickling is great... and yes, I started laughing along with the newscaster.

    Sure the slumber parties weren't co-ed...

  3. Apple Lady, don't go walking in the woods alone. It doesn't sound safe!

  4. I was just listening to a story about this on Radio Labs on NPR today. It must have been a rerun of this episode:

  5. That NPR show on laughter covers a lot of the stuff I found, and more. I saw that about the contagious laughter in Tanganyika but I decided not to include it because it wound up being more about mass hysteria than laughter. But it's pretty wacky. I'm curious about the professional laughers. I wonder what their lives are like after work?

    Jarred, thanks for the concern but it's really unnecessary. These are metro parks with lots of maintained paths.

    I knew you'd like the dog tickling one, Jason.

    And Elaine, I also saw a Youtube of some guy tickling his pet squirrel, and the squirrel was clearly laughing. So I'm sure there are still more animals (mammals, I'm guessing) that laugh.

  6. What a happy post! Love the videos.

  7. my grandma Bernice's laugh: eh eh eh eh eh eh-ah
    my mother Jeanne's laugh: whoo hoo hoo hoo hoo hoo hoo hoo hoo hoo hoo
    My brother Eric's laugh when he was little and up to no good; kil kil kil kil kil kil kil kil kil


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