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The Tiny And Terrifying
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Why your fingers can't tickle you

Turns out your brain stops you from tickling yourself on purpose

By Smartasaurus· 1 min read Curious

Your own brain spends its entire life actively pretending you aren't…

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The short version
  • Turns out your brain stops you from tickling yourself on purpose
  • A tickle is a survival reflex.
  • The feeling you cannot give yourself is the feeling your brain has decided is not worth your attention.

Your brain refuses to be surprised by your own hand. Try to tickle yourself, and the sensation is cancelled before it arrives.

The cancellation happens in the cerebellum, the dense lobe at the back of the skull that, among other things, predicts the sensory consequences of your own movements. Every time you reach for something, the cerebellum issues a small forecast to the rest of the brain: *here is what your fingers are about to feel*. When the real signal comes in matching the forecast, the brain quietly subtracts it. This is why you don't feel your own clothes most of the day, and why your voice sounds different on a recording — the live version was being predicted and dampened in real time.

A tickle is a survival reflex. It evolved to flag the unexpected touch of something small crawling on you — an insect, a parasite, a snake. For that alarm to mean anything, it has to fire only when the touch is genuinely unpredicted.

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Sources (2) — tap to view
  1. 1.Blakemore et al., Why can't you tickle yourself? (NeuroReport)
  2. 2.Cerebellum and self-prediction (Trends in Cognitive Sciences)
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