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Tom Ireland talks to Professor Sophie Scott about studying laughter - and why it's not just humans who get the giggles

The Biologist 62(1) p26-30

Professor Sophie Scott's research brings together understanding from speech sciences, psychology and neuroanatomy to understand how the human brain processes speech and vocal expressions. She is now best known for her work on laughter and has even recently made a foray into stand-up comedy.

Why are you studying laughter?

I'm generally interested in human communication and how our brains support that, particularly the voice – both how we perceive the information in voices and how we control the act of speaking.

As a vocal behaviour, laughter is surprisingly under-researched considering the frequency at which you encounter it. Understanding 'abnormalities' of negative emotions seems to be particularly important in western psychology, but also people think research on laughter is just trivial or ridiculous, and that's very hard to get round.

Why is laughter important?

Because it is a social behaviour and we use it a great deal. People think you are studying jokes, but it is in fact a complex, nuanced and common vocal expression.

One of the best estimates I've seen suggests in social situations people laugh around seven times every 10 minutes, even in experimental settings, which are not exactly hilarious. That's quite a lot, and certainly in that time people rarely scream or go "euurgh" with disgust.

In mammals generally, it has evolved as a social bonding behaviour and a very important one. In humans, it still is a social behaviour: you laugh more when you're with other people and you want them to like you; it establishes that you like them, that you are part of the same group as them, and that you agree or understand.

Is there a physiological difference between this social laughter and laughing uncontrollably at something funny?

We still don't know exactly, but there seem to be two systems in the human brain for vocalising. One is more recent in terms of our evolution and is based in the lateral motor areas, which is what you use for speaking.

People with severe damage in those areas and problems with their speech can still cry and laugh and do all sorts of non-verbal or automatic speech – they still swear in pain, for example. That seems to be because spontaneous vocalising is part of an older evolutionary pathway, which seems to be more like the basic system you find that controls vocal behaviour in other animals.

My suspicion is that posed social laughter may be more like speech, while really uncontrollable laughter might be part of this more central, older, midline pathway.

Do you have to try to make people laugh as part of your research?

Yes. For years I worked with posed stimuli, as there is no ethically acceptable way of making someone so frightened or angry that they actually make a noise. So when we started working with laughter, it was great, as we realised no one was going to bat an eyelid if we just tried to make people laugh. That's when we started making the set of stimuli for real and social laughing – we just did whatever it took to make people laugh and recorded it!

The problem is that you can find something very funny, but you're much less likely to laugh if you're on your own. So to make me laugh, we ended up having me watch my friend listening to something that I knew she would find funny. I could see her desperately trying not to laugh at it and it just made me laugh like a drain.

I saw that you use that well-known Irish news clip where a man slips on an icy pavement, which I love. Are there things that make people laugh across all cultures?

There are themes, such as slapstick, or what we call schadenfreude, but even with something that's really universally funny, there is always the possibility that one person just isn't laughing. For example, some older people shown that clip of the guy falling over on the ice will say: "That isn't funny at all – that happens to me."

Do many other animals other than humans laugh?

Yes, but with the proviso that we haven't been looking that widely.

In great apes, laughter is pretty easy to recognise because it sounds very similar to our laughter. There's a video of actor Robin Williams interacting with Koko the gorilla and he starts to tickle her. When she gets going, it's really beautiful: she has this great big open smile and she's shaking. There is good evidence found by Dr Marina Davila-Ross at Portsmouth University that chimpanzees have different types of laughter.

In other species of animal, we either haven't looked for it or we can't hear it. Jaak Panksepp in the US transduces the calls that rats make and noticed they produce a very different sound when they play with each other. Having tested it further, they are pretty sure it is laughter, as they make the sound when they are tickled. It sounds like a little chirrup.

It doesn't have to be sounds, of course. For example, dogs have a play 'face' that they put on when they are playing, which, if there was a noise associated with it, we would call laughter.

So animals laugh when they play and bond, but presumably they don't laugh at humour or funny things?

Well, it would be very difficult to prove if they did, but certainly their laughter tends to be much more physically centred: they are laughing because it tickles or they are laughing because they are playing. In humans, humour is like culture: a tremendously complex construct that changes wildly. Do you remember when everyone thought that "whatsuuppp" thing was funny?

Ha, yes, and then anyone still saying it a few months later was a total idiot.

Yes, it was about a week! Things that seem funny then become just really embarrassing. There's a tremendous link between humour and culture and fashion, but the actual laughter doesn't change very much. My son is currently obsessed with old Tony Hancock recordings and lots of it is very dated, but the audience laughter is exactly the same – those rhythms and ripples of laughter, and bursts when they really laugh hard.

Have you been able to look at someone laughing in real time using modern imaging techniques?

In theory, but one of the problems with functional imaging like functional MRI is it's very sensitive to movement. Even talking produces too much – and with laughter you can get huge movements across the torso, which makes everything move.

Someone has done a study where they found differences in the brains of people being tickled and laughing socially, but I'd like to know a lot more about that, because I suspect you might be missing a lot in the images because of the movement.

What is happening when we laugh uncontrollably?

One of the things I'm very interested in is why we can be overwhelmed by laughter – if you laugh hard, you can't breathe properly, and there is nothing you can do to stop it. There is even something called 'giggle incontinence', and some people pass out when they laugh.

Being overwhelmed by laughter suggests there are some really big motor changes that occur when we start laughing. You see a change in muscular tone and almost a weakness in humans when they laugh, which I haven't seen in other species: you don't get animals rendered helpless with laughter. Think of that clip of Brian Johnston and Jonathan Agnew laughing on the cricket commentary when they're both desperately trying not to because they know they'll get into trouble and they need to stop, but they can't do anything about it.

From an evolutionary perspective, there isn't really much reason why you want to be rendered helpless like that. It could be to do with the fact we have very different motor control over the muscles of the articulators in the ribs and chest wall that allow our speech to be complex, and maybe that gives laughter a route to get in and overwhelm us too.

I'd like to know more about the control of voluntary and involuntary vocalisations – crying is another one where you can be overwhelmed for 20 minutes. That doesn't happen if you're disgusted by something.

You've been doing stand-up as a way of telling people about your work. Has studying the science of laughter helped you become a better comedian?

No, unfortunately not, but I do love it, I think because I'm a huge show-off. When someone first suggested it to me, I couldn't think of anything worse, but then I did it and just had so much fun. I would really recommend it to other scientists as a way of telling people about their work.

Do you think your research might have practical uses?

I am funded by the Wellcome Trust for basic biomedical science, so it's fundamental research. However, I think a better grasp of the science of laughter could help our understanding of disorders that affect our ability to laugh, such as depression. It's also just a really good index or measure of how well people get on: couples who laugh a lot tend to stay together longer. I think that's worth knowing more about.

Professor Sophie Scott is Wellcome Trust senior Fellow at University College London (UCL) and group leader of the speech communication neuroscience group at the university's Institute of Cognitive Neuroscience. She can be found tweeting @sophiescottup

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