What does contagious laughter sound like?

Feel like a good laugh? Then why not take part in a listening experiment designed by UvA psychologists. Listen to someone else laughing out loud and rate how contagious you find their laughter. You can also add your own laughter fragment and thereby help the researchers find out what contagious laughter sounds like. Many mammals - such as rats, dogs, chimpanzees, squirrel monkeys and other primate species - produce laughter-like vocalisations when playing with their peers. Laughter provides a unique perspective on vocal signalling behaviour because it plays a role in both one-on-one interaction and interaction among larger groups. Humans begin laughing soon after their birth, at the age of around three months. This is long before they start talking.