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The science behind your laughter

The human laughter has been studied for many centuries. We know for example that there are several different types of laughter. Now, new studies reveal just how significant our laughter is for our social interactions.

Do you laugh with your mouth or your eyes? As strange as this question may sound, it does reveal whether your laugh is real or fake. What do your eyes have to do with your laugh, you wonder? Well, it is not only your mouth that shows a smile or a laugh, it is also your eyes. The French scientist Gauillaume Duchenne de Bologne (1806-1875) examined the human facial muscles during laughing.

While analysing which muscles are responsible for making us laugh, he came across two muscles: Musculus zygomaticus major, which controls the corners of our mouth and Musculus orbicularis oculi, which is responsible for the area around our eyes. However, there is a significant difference between these two: Musculus zygomaticus major can be controlled by us, whereas Musculus orbicularis oculi is completely out of reach of our deliberate control. 

The appeal of laughter

This means that only when a laugh is genuine, both muscles are activated. Only then do wrinkles appear around our eyes and the corners of our mouth go up. A fake laugh on the other hand can be recognized when only the corners of the mouth go up but the eyes remain the same. Next time you smile at someone, try to pay attention to the reaction you get back.

You will notice that most people will smile back at you. This also happens when you fake a smile. Even monkeys have the ability to put on a fake smiling face. It is believed that smiling and laughing are a sign of submission and can therefore defuse conflict. It is therefore a crucial part of our behaviour and is used in the most diverse situations of life. 

Laughter in science

A key component of making business is trust. You would probably agree that trusting in what a salesperson is saying to you is vital in making you buy their product. A team of scientists at the Max-Planck-Institute for Evolutionary Biology and the Toulouse School of Economics set out to further analyse this. They wanted to know how important laughter is for evaluating how trustworthy our conversation partners are. In their experiment, they had two people interact with each other.

The first agent received 4 Euro and was given the choice to either keep the money or confide it to the other person (here called fiduciary). If the first agent decided to give the money to the fiduciary, the amount was tripled immediately. The fiduciary then had the chance to decide what to do with the tripled amount of money. He could either give part of it back to the first person or keep the entire amount for himself.

Things could therefore go very well or very badly for the first agent: On the one hand, he is at risk of losing all of his money if he gives it away. On the other however, he also has the chance to get back more money than he initially gave away. Is it worth taking the risk? In order for the first agent to better evaluate the fiduciary, he was shown a short video of the latter introducing himself. The words used for the introdution were always the same; a prefabricated text composed by the scientists. 

The type of laughter is key

First, the scientists examined how the fiduciary was perceived. One factor here was to see how genuine his smile was believed to be and how trustworthy he seemed. The findings revealed that the more a fiduciary’s smile was perceived to be real, the more trustworthy he was believed to be by the first agent. Accordingly, in these cases, the first agent was much more willing to hand over their 4 Euro. And surprisingly, this strategy paid off: Those fiduciaries whose smile was perceived to be genuine, on average also transferred the money back to the first agent.
Science could therefore show that the human laughter has a special kind of status in our social interactions. No matter if we are talking to a friend, confiding in a family member, or making business with a partner – our laugh – both fake and real – is crucial in deciding what the outcome will be. 

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1: Max-Planck-Institut for Evolutionary Biology: Smiling builds trust

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