You’re Not Fooling Anyone With Your Pretend Laughter

Posted on April 7, 2015

Scientists are learning about not only the ways in which people hear and categorize laughs, but also how human laughter relates to similar vocal behaviors across the animal kingdom. We have now uncovered many clues about the origins of this fascinating and ubiquitous behavior: While laughter might seem on the surface to be about jokes and humor, it turns out that it's really about communicating affiliation and trust.

Laughter triggers the release of brain endorphins that make us feel good, and it reduces stress. There is even evidence that we experience a temporary slight muscle weakness called cataplexy when we laugh, so we could be communicating that we are unlikely (or relatively unable) to attack. But laughter is not always made in fun, and can be quite hurtful (e.g., teasing). Laughter is a powerful signal with huge communicative flexibility.

In one line of research in my Vocal Communication Lab at UCLA, we have been playing recorded laughs to listeners and asking them, is this laugh "real" or "fake"? Our recorded laughs were taken from real conversations between friends in a laboratory setting, or produced on command, also in the lab. Listeners were able to tell the "real" laughs from the "fake" laughs about 70 percent of the time.

A fake laugh is produced with a slightly different set of vocal muscles controlled by a different part of our brain. The result is that there are subtle features of the laughs that sound like speech, and recent evidence suggests people are unconsciously quite sensitive to them. For example, if you slow down a "real" laugh about two and half times, the result is strangely animal-like. But when you slow down human speech, or a "fake" laugh, it sounds like human speech slowed down.

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Source material from Time