Why we laugh in conversation

We tend to think of laughter as the reaction to something funny: a joke is told, the punchline lands, people laugh. That happens. But when scientists stopped asking people about laughter and started listening to it in the wild, a very different picture appeared. Most of the time, we are not laughing at anything. We are laughing with someone.

Eavesdropping on laughter

The neuroscientist Robert Provine spent years studying laughter in ordinary life. With his students, he recorded around 1,200 natural "laugh episodes" overheard in public places such as shopping centres and university campuses, noting what was said just before each laugh.

Only a small minority of those comments, somewhere around 10 to 20 per cent, were remotely humorous. The rest were everyday remarks: greetings, plans, small observations. People were laughing to keep the conversation warm, not because anything was funny.

Provine also found that speakers laugh more than their listeners, roughly half as much again. If laughter were mostly a reaction to humour, you would expect the audience to do most of it. Instead, the person talking punctuates their own sentences with it, a bit like a friendly comma that says "we are fine, keep going".

A social signal, not a reflex

In a separate diary study, Provine and Kenneth Fischer asked people to record when they laughed during the day. People laughed around thirty times more often when they were with others than when they were alone. Laughter, it seems, is built for company.

The neuroscientist Sophie Scott at University College London, who has spent much of her career on laughter, describes it as one of the main ways we show that we like and agree with each other. Her work with colleagues also suggests that listeners can usually tell spontaneous laughter from posed, polite laughter, and that the two are produced in different ways.

Most laughter means: I am with you.

And this seems to be human, not cultural. In a 2016 study led by Gregory Bryant, listeners in 24 societies around the world heard brief clips of two people laughing together. From only a second or two of laughter, they could tell better than chance whether the two laughers were friends or strangers. A laugh carries information about a relationship, and people almost everywhere can read it.

What this means on a call

On a voice call you cannot see a smile or a nod. That makes laughter one of the few warmth signals that travels down the line, which may be part of why a call can feel more connected than a page of text. A few practical takeaways:

• You do not need to be funny. Most laughter follows ordinary remarks, so you only need to be friendly.
• Let small laughs out. A light laugh at a mildly amusing moment tells the other person the conversation is going well.
• Do not fake it. Forced laughter is easier to detect than we assume, and it can make things feel less genuine.
• Notice when they laugh. If someone laughs as they talk, they are probably relaxed, and it is a good moment to ask a slightly more personal question.
• Share the laugh. Two people laughing together is the version researchers find most bonding, and the one listeners worldwide recognise as friendship.

The next time you find yourself laughing at something that is not funny at all, do not worry that you are being strange. You are doing exactly what laughter evolved to do. Who did you last laugh with, and what were you really saying?

Sources: Provine, R. R. (1993), "Laughter punctuates speech: Linguistic, social and gender contexts of laughter", Ethology; Provine, R. R. (1996), "Laughter", American Scientist; Provine, R. R. & Fischer, K. R. (1989), "Laughing, smiling, and talking: Relation to sleeping and social context in humans", Ethology; Provine, R. R. (2000), Laughter: A Scientific Investigation; Scott, S. K., Lavan, N., Chen, S. & McGettigan, C. (2014), "The social life of laughter", Trends in Cognitive Sciences; Bryant, G. A. et al. (2016), "Detecting affiliation in colaughter across 24 societies", Proceedings of the National Academy of Sciences.