WEBVTT - Why Can't You Tickle Yourself?

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<v Speaker 1>slash brain Stuff. Welcome to brain Stuff from How Stuff Works. Hey,

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<v Speaker 1>I'm Christian Sager and this is brain Stuff pop quiz

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<v Speaker 1>hot shot. Have you ever tickled an ape? Before? It

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<v Speaker 1>could work as tickling as common between many types of primates.

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<v Speaker 1>What about a rat? You ever tickled one of those?

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<v Speaker 1>You'd know if you had, because rats let out these little,

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<v Speaker 1>high pitched chirps when you tickle them, kind of like

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<v Speaker 1>rodent laughter. Okay, so maybe some of you beast masters

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<v Speaker 1>out there have tickled both a rat and an ape.

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<v Speaker 1>But can you tickle yourself? Probably not, because that is

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<v Speaker 1>kind of impossible. Now, before we continue, let's do a

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<v Speaker 1>quick primer on how tickling works. Under your skin. There

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<v Speaker 1>are millions of nerve endings that alert your brain whenever

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<v Speaker 1>you touch something. A light touch, what we usually associate

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<v Speaker 1>with tickling, is analyzed by two regions of your brain,

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<v Speaker 1>the somato sensory cortex, which processes touch, and the anterior

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<v Speaker 1>singulated cortex, which processes happiness. Together they process the two

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<v Speaker 1>types of tickle sensations we can experience. The first is nismesis.

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<v Speaker 1>This is the light sensation you feel when something like

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<v Speaker 1>a feather brushes against your skin, maybe giving you goose bumps.

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<v Speaker 1>The second gargolesis is more like when your older brother

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<v Speaker 1>holds you down and tickles you until you laugh so

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<v Speaker 1>hard you pee your pants. This is the kind of

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<v Speaker 1>tickling you can't replicate yourself. Evolutionary biologists believe that the

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<v Speaker 1>reason we laugh when we're tickled is an innate, submissive

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<v Speaker 1>response to a potential attacker. It's kind of like when

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<v Speaker 1>a dog rolls over on its back and exposes its

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<v Speaker 1>kill points to you. These same biologists theorized that we

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<v Speaker 1>developed tickling so we could teach our children how to

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<v Speaker 1>defend themselves from attacks. So think about it. The areas

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<v Speaker 1>where we're the most ticklish, the under arms, the stomach,

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<v Speaker 1>the neck, they're also the most vulnerable to attack. Now,

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<v Speaker 1>this is some black Widow red room lethal training coming

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<v Speaker 1>up here, so pay attention. Your under arm is home

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<v Speaker 1>to veins and arteries, and because your rib cage doesn't

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<v Speaker 1>protect it, someone could easily access your heart through there,

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<v Speaker 1>especially with a long enough blade. Likewise, your stomach doesn't

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<v Speaker 1>have any defensive bones, and your neck also has two

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<v Speaker 1>important arteries as well as your trachea, bringing air to

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<v Speaker 1>your lungs now We're aware of all of these points

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<v Speaker 1>of vulnerability, but we still can't tickle ourselves at them

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<v Speaker 1>because our brains know that our own hands don't pose

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<v Speaker 1>a legitimate threat. Essentially, you can't tickle yourself because of

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<v Speaker 1>self awareness. Mri I studies have shown that your seahbellum

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<v Speaker 1>actually alerts the rest of your brain when you're about

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<v Speaker 1>to tickle yourself. This filters it out as unnecessary information

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<v Speaker 1>and mutes the sensation. So theoretically, any situation that confuses

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<v Speaker 1>your brain's ability to predict its own actions should allow

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<v Speaker 1>you to tickle yourself right well. Sometimes schizophrenics, for example,

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<v Speaker 1>can tickle themselves. This is probably because their brains sometimes

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<v Speaker 1>attribute their behavior to an alien source. Researchers theorized that

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<v Speaker 1>schizophrenic brains have biochemical or structural variations that keep the

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<v Speaker 1>cerebellum from alerting its owner when they're about to tickle themselves.

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<v Speaker 1>This means they can't tell the difference between their hands,

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<v Speaker 1>your hands, or the tentacles of a giant squint. Check

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<v Speaker 1>out the brain stuff channel on YouTube, and for more

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<v Speaker 1>on this and thousands of other topics, visit how stuff

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