Itches, Twitches, Tickles, and Pops

A tickle can be titillating or traumatizing (If you had a big sister who used to hold you down and perform tickle-torture, it may be the latter). Ticklish sensations come in two categories, with giggle-inducing titles: Knismesis is that light-as-a-feather sensation, and gargalesis is the kind of tickling that gives you that big belly-laughing feeling. Some of the intriguing questions about the topic of tickle include why touch would inspire laughter and why we can't tickle ourselves.

Why would being poked and jabbed and stroked make us laugh, anyway? What's so funny about being tickled? Is there some link between humor and touch? Some researchers think of tickle as a kind of "play fighting," a safe, lighthearted way to learn how to defend ourselves. Others believe that the smiles and laughter you get from tickling are different from the smiles and laughter you get from a funny joke or a happy moment. Could those giggles and grins be more like nervous laughter or express submission to a superior? This seems possible, since most of us know the feeling of being tickled until it hurts, until we have to scream "Uncle!"

As to why we can't tickle ourselves, it may be because our brain is simply so smart and responsive. When someone else tickles us, our brain just doesn't have a chance to plan for a calm, measured response. Instead, most of us go into ticklish reflex-mode - giggling, laughing, twitching, and eventually pulling away like we're actually in pain. But when we try to tickle ourselves, it is thought that a part of the brain, predicts the action and plans ahead for it. It seems that the whole surprise and suspense factor delays our brain's reaction long enough for the ticklish reflex to kick in.

Tickle research may seem like a laughable use of researchers' time, but it's turning up some fascinating theories about brain disorders, including schizophrenia. Looking at the brains of people who hear voices or experience delusions, it appears that this predictive ability doesn't work right. A person might think a particular thought but hear it as a "voice" because they lack the awareness to recognize it as a thought they generated on their own - sort of like being able to tickle themselves. Who knew a tickle could tell so much?