Why you can't tickle yourself: what your brain knows that your skin does not
The Oxford tickle test: is it knowing, or moving, that stops you tickling yourself?
When you tickle yourself, you know exactly when and where the touch will land. A machine built in Oxford in 1971 tested whether that is enough to take the tickle away.
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Rono still thinks it is simple: with your own hand, you know when and where the touch will come, and that is all. Miva has read about a test of this very idea, in Oxford, in 1971. A handle moves a soft tip across the sole, the bottom of a bare foot. Imagine the foot is yours, and the scientist Lawrence Weiskrantz holds the handle.
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He moves the handle. The tip runs along your sole, you kick, and you laugh. On a scale, you call it very tickly.
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Now you move the handle yourself, in the same way. Same tip, same foot, and it hardly tickles. Rono's idea seems right: you know when and where the touch will land.
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Then comes the clever test. Your hand only rests on the handle, and he moves it. Your hand goes along, so you still feel when and where the tip will go. It tickles less than when he moves the handle alone. But it tickles more than when you move it yourself.
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So knowing takes some of the tickle away. The biggest drop comes when your own brain gives the order to move. Something in that order warns your brain that a touch is coming. Next, we look inside the brain to find out what.