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From derisive snickers to excited giggles to unrestrained howls of mirth, laughter is remarkably nuanced and varied. UVA assistant professor of psychology Adrienne Wood studies how we communicate through this universal human behavior. In a recent paper for the journal Affective Science, Wood’s lab examined the acoustic profiles of nearly 3,400 laughs to consider whether the sound of laughter might be a reliable indicator of social context.   

In the study, researchers selected short, humorous videos in three categories. Reward videos were “highly humorous in a straightforward sense,” while affiliation videos—think cute puppies and babies—“elicited responses associated with tenderness, care … or cuteness,” Wood writes. Finally, dominance videos—of “epic fails” and pratfalls—“elicited responses of derision [and] ridicule.” Study participants watched the videos individually, chose the ones they perceived to fit the intended context, and then watched and discussed them in pairs. Those conversations were recorded, and anything the researchers noted as laughter was extracted for analysis.

The results confirmed that laughter evoked by the different categories had distinct acoustic properties. Reward laughter was louder, longer and more disinhibited, the kind of infectious laugh that is rewarding to listen to, Wood says. Affiliation laughter was quieter, more muffled and shorter, Wood says, and appears to serve as a kind of nonverbal social lubricant. “People laugh like this constantly in conversation,” she says. Finally, dominance laughter was noisier and brassier, “like having a trumpet go off in your ear,” Wood says. “It is actually unpleasant to listen to.”

The research supports the idea that laughter’s acoustic properties are not completely random and help convey meaning, Wood says. “Laughter serves many functions,” she says. “It’s not just about people being funny.”