http://www.sciencemag.org/news/2018/06/can-you-tell-real-laugh-fake-one

Some laughs are genuine reactions to hilarity. Others are more contrived—fake, even. But, according to a new study, people can usually tell real laughs from fake ones, regardless of cultural differences.

In the first cross-cultural experiment of its kind, researchers asked 884 people from 21 different cultures in six regions around the world, from Peru to South Korea, to listen to recordings of real, spontaneous laughter, and fake, “volitional” laughter recorded from college-aged, U.S. women. On average, nearly two-thirds of listeners in each culture could tell the difference, the team reports in a study accepted for publication in Psychological Science.