Why do we laugh?

by Sophie Scott

Written by Professor Sophie Scott FMedSci, British neuroscientist and Wellcome Trust senior fellow at University College London
Laughter is bizarre: we like to laugh, and value it, but we can also find it irritating and can take great exception to it. Conversely, we almost never recognize the real reasons behind why we are laughing, and we do it a lot more than we realize.

I started researching laughter scientifically around 15 years ago, as part of a program of research into human emotional vocal behavior— when and how we make sounds like screams, or sobs. Following existing systems, I classified laughter for many years as the kind of sound we make when we are amused—because it made implicit sense that laughter is what we do when we find something funny. However, as I read more about it I came across a lot of work by the neurobiologist Robert Provine, who has shown that though we think we laugh most at jokes and comedy, if you actually watch people, you find that laughter mostly occurs in purely social settings, and is not a response to comedy.

Indeed, Provine has shown that laughter is strongly primed by social factors, so much so that people are 30 times more likely to laugh if there is someone else there than if they are on their own. This seems to be because, in the wider world of mammals, laughter has more to do with social bonding and play behavior than it is a property of humor. Jaak Panksepp— the Estonian-born neuroscientist and psychobiologist—who does beautiful work on laughter in rats, has described laughter as, at its heart, an invitation to play.

We have found that laughter is the only positive expression of emotion that is cross-culturally recognized— wherever you go in the world, laughter is recognizable. However, there are important cultural and contextual factors that modulate how appropriate laughter is, and whether or not people will join in. For example: laughter is highly contagious, but people are much more likely to ‘catch’ a laugh from someone they know than someone they do not know. Laughter is considered more or less appropriate in ‘polite’ settings depending on many factors—in many more formal Japanese business settings, laughter would typically be considered impolite, and will be overly avoided. This sense of when laughter is appropriate is not confined to Japan: I was once in a very difficult phone conversation with a displeased colleague. My colleague’s displeasure deepened greatly when they overheard laughter from people in the same room as me, and they assumed people were laughing at them. Nothing I said could convince them otherwise, or stop them from being deeply offended.

Even within a particular culture, many different factors affect how we engage with laughter. People with higher status tend to laugh less than people around them who have lower status. However, we don’t know if this is because the higher status individuals are withholding their laughter, or because the lower status people are laughing relatively more to get the attention and affection of the higher status person.

We have found that people whose brains are primed to join in with laughter (to catch the laughter contagiously) are also better at telling if laughter is spontaneous or faked. Work going on in my lab at the moment is seeking to understand this variation in more detail: we are working with people who have depression, who anecdotally find a lot of normal ‘social’ laughter extremely irritating. In gelotophobia, people who are actively distressed by laughter tend to assume it is directed at them, reacting violently. These are kind of people who hear someone laughing when they’re walking down the street, and punch the person who laughed.

One of our findings is that the perception of laughter takes a relatively long time to develop; such that we are learning about laughter and what it means throughout our childhood, adolescence, and early adult lives. This may make laughter perception particularly sensitive to factors (such as mood disorders) that might impact the scale of that development.

One of the things I find striking about laughter is that we attribute it to people—we’ll say “he’s got a great sense of humor,” about someone when we actually mean, “I laugh a lot around him, because I like him.” Similarly, we’ll often accuse people of laughing inappropriately when what we mean is something more like, “I do not like that person and I don’t laugh when they laugh.” We attribute our own laughter (or lack of it) to the characteristics and/or actions of other people, when the laughter (or lack of it) is actually telling us much more about our own feelings. That might be an even more important reason to take laughter seriously; I think that in our hearts, we know this to some extent. One of the reasons we value laughter is that there can be a real truth to it; it can often reveal genuine affection between people.

When my father thought he was dying—many years ago—he was silent for a long time and then suddenly said, “We have laughed a LOT, haven’t we?” At the time I didn’t quite follow the importance of this, but now I can see that he was right to have spent some time thinking about laughter in his life: we tell each other it’s about jokes, but laughter is— at its core—love.

Image C/O BBC