特别广播英语第 223 课：Why Can't You Tickle Yourself 为什么自己哈痒不觉痒？-1

Have you ever thought about why people are ticklish?你有没有想过人为什么会怕痒？

According to scientists, ticklishness is a defense mechanism humans developed against bugs, spiders, and other critters that may be touching our skin. 根据科学家的观点，怕痒是一种防御机制，是人类把它培养来对付那些可能接触我们皮肤的虫子、蜘蛛或其他生物。

Feeling ticklish is our built-in response to predators or threats, and combines the sensations of touch and pain. 怕痒是我们对侵扰者或威胁产生的内在反应，它使触觉和痛觉结合起来了。

The part of the brain that is associated with tickling is the cerebellum. 脑部与怕痒有关的部位是小脑。

It monitors our movements, but ignores movements not perceived as a threat. 小脑监控我们的一举一动，但对其认为不具威胁性的活动，往往会忽视。

For example, we do not notice our vocal chords moving when we speak, but we may jump if someone touches us on the shoulder. 举例来说，我们说话时不会察觉声带的振动，但是如有人触摸我们的肩膀时，我们可能会吓一跳。

This selective perception is probably the reason why we cannot tickle ourselves. 这种选择性的知觉或许就是我们无法自已哈痒的原因。

We only feel ticklish if we detect a sense of invasion or attack. 我们只会在察觉受到侵犯或攻击时才会觉得痒。

If we try to tickle ourselves, our brains anticipate this "attack" and prevent us from feeling panicked. 如果试着替自己哈痒，脑部会自动预感到这种“攻击”从而使我们感觉不到惊吓。

Strangely enough, even if a person knows that they are about to be tickled, the fear of being touched may cause the same "ticklish" reaction. 奇怪的是，即使有人知道他要被哈痒了，担心被人触摸，也会引起同样“怕痒”的反应。