Kate Murphy, The Science of the Fake Laugh, The NYTimes:
Laughter at its purest and most spontaneous is affiliative and bonding. To our forebears it meant, “We’re not going to kill each other! What a relief!” But as we’ve developed as humans so has our repertoire of laughter, unleashed to achieve ends quite apart from its original function of telling friend from foe. Some of it is social lubrication — the warm chuckles we give one another to be amiable and polite. Darker manifestations include dismissive laughter, which makes light of something someone said sincerely, and derisive laughter, which shames.The thing is, we still have the instinct to laugh when we hear laughter, no matter the circumstances or intent. Witness the contagion of mirthless, forced laughter at cocktail parties. Or the uncomfortable laughter that follows a mean-spirited or off-color joke. Sexual harassers can elicit nervous laughter from victims, which can later be used against them.
Researchers at the University of California, Los Angeles, found that people mistake fake for genuine laughter a third of the time, which is probably a low estimate as the fake laughter that subjects heard in the experiment was not produced in natural social situations. While laughing on command is rarely convincing (think of sitcom laugh tracks), “your average person is pretty good at fake laughing in certain circumstances,” said the study’s lead author, Greg Bryant, a cognitive psychologist who studies laughter vocalization and interpretation. “It’s like when people say, ‘I’m not a good liar,’ but everyone is a good liar if they have to be.”
The real deal:
Genuine laughter, real eruptions of joy, are generated by different neural pathways and musculature than so-called volitional laughter. Contrast the sound of someone’s helpless belly laugh in response to something truly amusing to a more throaty “ah-ha-ha,” that might signify agreement or a nasal “eh-heh-heh” when someone might be feeling uneasy. “A fake laugh is produced more from areas used for speech so it has speech sounds in it,” Dr. Bryant said.There is also a big difference in how you feel after a genuine laugh. It produces a mild euphoria thanks to endorphins released into your system, which research indicates increases our tolerance to pain. Feigned laughter doesn’t have the same feel-good result. In fact, you probably feel sort of drained from having to pretend. Recall your worst blind date.