There are two kinds of tickles. Knismesis is a soft, gentle kind of tickling, such as when an insect crawls across your skin, or someone strokes you with a feather. But here we’re talking about the other kind. It’s called gargalesis and is the full-on, go-for-the-ribs or armpits tickling that makes you laugh out loud and wiggle and squirm.
Stop and think about it for a minute, and you’ll notice something very odd about tickling. When you’re being tickled, you laugh, sometimes a lot. That’s a sign of happiness and joy, right? But you also squirm and try to get away from the tickler. You might even push them away or beg them to stop, even as you erupt into yet more spasms of giggles and shrieks. What gives? Is this fun or not?
Sure, we laugh when we’re tickled, but it’s very different from the kind of laughter that follows hearing a joke or seeing a funny meme, explains Alicia Walf, a neuroscientist at Rensselaer Polytechnic Institute. Those experiences are processed in the frontal lobe, where memory and abstract thought are processed.
The sensation of being tickled, however, is processed in the limbic system, the part of the brain involved in emotions. Those emotions can be either negative or positive, explains Walf, but they’re very basic. The limbic system is the oldest part of the brain, the seat of the “fight or flight” response.
