In partnership with The Conversation, #Trending brings you Curious Kids, a series where we ask experts to answer questions from children.
Why can’t we tickle ourselves? – Florence, aged 12, Cambridgeshire, UK
Aysha Bellamy, PhD candidate, Royal Holloway, London:
"Thanks for the question, Florence. The short answer is that we humans can’t tickle ourselves because we’ll already be expecting it. And a big part of what makes tickles ticklish is the element of surprise.
Tickling is an important sign that someone or something is touching you. In general, there are two types of tickles. There are good tickles, like when your family or friends tickle you and make you laugh. And there are bad tickles, like when you can feel a bug on you.
The motor system is a thing that most animals – including humans – have in their body. It’s made up of our muscles and brain, and it’s what lets us move.
Every time that you move, your brain sends a plan to your muscles. It does this by sending the plan, in the form of electrical signals, along the nerves that run like wires through your body.
This plan tells the muscles when and how to move, and also what to expect when we have moved.
We have five senses – sight, smell, taste, touch and hearing. The plans sent to your muscles guess how each of these senses may change after you have moved.
So, when you try to tickle yourself, your brain sends the plan through the nerves – it tells the muscles in one arm to move to do the tickling, and it also tells your other muscles that the tickle is coming.
When somebody else tickles you, your muscles haven’t got a plan from your brain, so the feeling is surprising – and ticklish!
But you can’t tickle yourself because your brain is always one step ahead, telling your muscles and senses what to expect and stopping you from giving yourself a surprise. But then, maybe it’s better that way."
. To read the rest of Bellamy’s answer, got to theconversation.com
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