Why Can't You Tickle Yourself?

Owl

Can you tickle yourself? [em03]

Go on — try it now. I bet you can't tickle yourself! See, it's impossible — but why? After all, we can laugh at our own jokes! Well, it looks as if scientists have finally found an answer to this ticklish question!

Picture this! You're about to try and tickle yourself on the foot, fingers poised ready to strike. Just as they reach your bare skin, a message is sent to the brain, Relax, it's just you, don't get excited! Your brain stands down and you don't feel the tickle.

Owl

The spoil sport with a funny name!

The message is produced by a part of the brain called the cerebellum, which is a cauliflower-shaped region at the base of the brain. According to researcher Sarah-Jayne Blakemore, the cerebellum anticipates the sensation caused by tickling yourself and tells the rest of the brain to ignore it.

But why does it do this?

It all comes down to protection! The brain needs to be able to ignore predictable everyday sensations, so it can be ready for more important ones. Imagine if it responded dramatically every time the soles of your feet touched the ground, or you blinked your eyes. Instead, it must be ready to react to unexpected, potentially dangerous sensations like, say, a red-back spider crawling down your neck.

What happens when someone else tickles you?

Interestingly the cerebellum can’t predict a sensation caused by an external factor, such as someone else tickling you, even if you can see it’s coming! That means if someone else tickles you, there’s no warning message sent to the brain and you end up feeling ... well... tickled!

Owl

But can you fool yourself?

Is there a way of somehow fooling your brain into responding to your own tickle? The answer is yes, according to John Bradshaw, a psychologist at Monash University, and the key is surprise. He says the ticklish sensation can be restored using a ‘tickling machine’ which allows you to initiate a self tickle, but which delays before actually touching your skin.

Owl

Go to more on this to find out more about Sarah’s research.

Writer: David Seignior Editor: Berry Billingsley

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Or like to know more about it, go to Hack 65: Why Can't You Tickle Yourself? (PDF) to read...a fascinating story.

[此贴子已经被作者于2005-7-8 9:04:01编辑过]

Owl

I just tried with a pencil - result is the same as your own finger

Also, I think it is all about your partner who touches you.

If your partner follows your command and plays dumb, your brain can predict the touch stimulus by his finger accurately and there is no tickle. If your partner does not follow your command, there is mismatch between your brain's predication and his/her touch stimulus and there is tickle.

Try it, or would you ask me to tickle you so we can try if we will fool your brain? [em04]

Owl

英国科学家于6月28日表示，人脑能提前意识到一些不重要的感觉，比如来自自身的触摸等，因此它就可以将“关注”的重点放到一些更重要的外界接触上。而这一结论也就能对为什么人们胳肢自己时感觉不到痒的现象做出解释。

No wonder I feel less pain every time I cut myself...how about you?