It’s one of the most popular online videos ever produced, having been viewed 355 million times on YouTube. At first glance, it’s hard to understand why the clip is so famous, since nothing much happens. Two little boys, Charlie and Harry, are sitting in a chair when Charlie, the younger brother, mischievously bites Harry’s finger. There’s a shriek and then a laugh. The clip is called “Charlie Bit My Finger—Again!”
Why has this footage gone viral? The answer, according to a new study by Jonah Berger, an assistant professor at the University of Pennsylvania’s Wharton School, has to do with the visceral emotions it arouses in viewers.
Here’s the thing about Harry and Charlie—they are incredibly expressive kids. In the span of 56 seconds, we see their faces go from anticipation to agony to laughter. Just when we’re worried that Harry might actually be hurt, he breaks out in a wide smile. The relief is palpable, the delight infectious. (Harry’s adorable British accent doesn’t hurt, either.)