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Why Can't You Tickle Yourself?


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Channel: BrainStuff - HowStuffWorks
Categories: Biology   |   Psychology   |   Science  
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It’s almost impossible to trick your brain so you can tickle yourself. Unless you're schizophrenic…

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Pop quiz hot shot. Click “like” if you’ve ever tickled an ape before. It could work, as tickling is common between many types of primates.

What about a rat? Ya ever tickled one? Then click “like” again. You’d know if you had, because rats let out these high-pitched chirps when you tickle them… kind of like “rodent laughter.”

Okay, maybe some of you Beastmasters out there have tickled both a rat and an ape. But can you tickle yourself? Probably not… because that’s kind of impossible.

Before we continue, let’s do a quick primer on how tickling works. Under your skin there are millions of nerve endings that alert your brain whenever you touch something.

A light touch -- what we usually associate with tickling -- is analyzed by two regions of your brain, the thesomatosensory cortex (which processes touch) and the anterior cingulated cortex (which processes happiness). Together they process the two types of tickle sensations we can experience.

The first is “knismesis.” This is the light sensation you feel when something like a feather brushes against your skin… maybe giving you goosebumps.

The second, “gargalesis” is more like when your older brother holds you down and tickles you until you laugh so hard you pee your pants. This is the kind of tickling you can’t replicate yourself.

Evolutionary biologists believe that the reason we laugh when we’re tickled is an innate submissive responsive to a potential attacker. These same biologists theorize that we (humans) developed tickling so we could teach our children how to defend themselves from attacks.

Think about it, the areas where we’re most ticklish – the underarms, the stomach, the neck -- are also the most vulnerable to attack.

This is some Black Widow/Red Room lethal training coming up here, so pay attention. Your underarm is home to veins and arteries. And because your rib cage doesn’t protect it, someone could easily access your heart through there, especially with a long enough blade.

Likewise, your stomach doesn’t have any defensive bones. And your neck also has two important arteries, as well as your trachea bringing air to your lungs. We’re aware of all of these points of vulnerability, but we still can’t tickle ourselves at them because our brains know that our own hands don’t pose a legitimate threat.

Essentially, you can’t tickle yourself because of self-awareness. MRI studies have shown that your cerebellum actually alerts the rest of your brain when you’re about to tickle yourself. This filters it out as unnecessary information and mutes the sensation. So, theoretically any situation that confuses your brain’s ability to predict its own actions should allow you to tickle yourself. Right?

Well… sometimes. Schizophrenics for example can tickle themselves. This is probably because their brains sometimes attribute their behavior to “an alien source.”

Researchers theorize that schizophrenic brains have biochemical or structural variations that keep the cerebellum from alerting its owner when they’re about to tickle themselves. This means they can’t tell the difference between their hands, your hands or… the tentacles of a giant squid.


TICKLISH MONKEY?. (2012). Scholastic SuperScience, 23(6), 2.

Dixit, J. (1996). A ticklish situation. Psychology Today, 29(6), 16.

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