We have all experienced it. Is that person laughing with me or taunting me? It is a complex task for the human brain to spot the difference but scientists have now discovered how this mechanism works.
Research carried out by scientists from the German city of Tuebingen now shows how precisely the brain processes the different types of laughter signals.
In an article published in the US journal PLOS ONE, the researchers report that positive non-verbal communication, such as joyful laughter, releases different reactions compared to negative signals like a taunt.
The neuroscientists hope their findings will one day lead to improved treatment for patients suffering from pathological anxiety disorders and other psychological illnesses.
What is laughter?
Laughter evolved as non-verbal communication to assist social interactions as shown by findings that young apes and rats can laugh.
"With animals, for example, it can be seen when they play chasing games with one another to learn how to catch prey," explained Dirk Wildgruber from the University of Tuebingen.
"It is relevant as a reward signal that increases the readiness of the parents and sibling animals to play with the youngster. This prepares the animal for later challenges," the professor said.
"Laughter is a very strong signal when it comes to social interaction. A person feels accepted when he is smiled at. However, a person feels excluded from the group when on the receiving end of a taunt," said Wildgruber, who is a scientist and doctor of psychiatry.
How the brain processed laughter
As part of their research, Wildgruber and his team exposed their test subjects to different laughter sounds and measured how these were processed in the brain.
The scientists found that when we hear a person being tickled, the neural connections in our brains are mainly just doing acoustic analysis of quite a complicated noise.
By contrast, when processing taunting and friendly laughter types, we activate brain areas associated with mentalizing and forming visual associations. Visual imagery may support the formation of inferences on the intentions of our social counterparts.
"This is extremely relevant for our patients in psychiatry," says Wildgruber.
In many psychological illnesses such as pathological anxiety, depression or schizophrenia, the ability to recognize non-verbal signals is often stunted.
The experts next want to investigate how they can treat the laughter perception network in the brains of people suffering with these mental illnesses.
They hope to find out which parts of the brain need to be stimulated to help patients undergoing psychotherapeutic treatment, said Wildgruber.
However, it will take a long time before the methods can be used in medical practice.
(Picture: Group of people laughing from Shutterstock)