Most of us have a ticklish spot somewhere on our bodies, and it is usually pretty easy to find.
我们大多数人的身上都有一个怕痒的地方，这个地方通常很容易找到。
For some it's just above the knee, for others it's the back of the neck, and some of us go into fits of laughter if someone grabs our sides.
对一些人来说，它就在膝盖上方；对另一些人来说，它就在脖子后面；我们当中还有一些人如果被抓住身体侧面就会大笑不止。
Laughing when another person tickles you is a natural reaction.
当别人挠你痒痒时，笑是一种自然的反应。
Scientists have discovered that the feeling experienced when we are tickled causes us to panic and is a natural defense to little creepy（爬行的） crawlers like spiders and bugs.
科学家发现，我们被挠痒痒时的那种感觉会让我们感到恐慌，这也是对蜘蛛和虫子等让人害怕的小爬虫的一种自然防御。
Slight tickles from insects can send a chill through your body, letting you know something is crawling on you.
虫类的轻微搔痒会让你全身发冷，让你知道有东西在你身上爬行。
That same ticklish feeling sends us into a state of panic and elicits a response of uncontrollable laughter if a person tickles us.
这种发痒的感觉让我们陷入恐慌，如果有人挠我们痒痒，我们就会忍不住大笑。
It's the moment that you least expect to be tickled and that causes you to feel extremely uneasy and panicked, which leads to the most intense ticklish feeling（痒感）.
这是你最不希望被挠痒痒的时刻，也是让你感到极度不安和恐慌的时刻，从而会导致最强烈的痒感。
Even if you do know that you are about to be tickled, the fear and unease of someone touching and possibly hurting you causes you to laugh.
即使你知道自己要被挠痒痒了，对有人触摸你并可能伤害你的恐惧和不安也会让你发笑。
Some people are so ticklish that they begin laughing even before they are touched.
有些人特别怕痒，甚至在被触摸之前就开始笑了。
So, if someone else's touch can tickle us, why can't we tickle ourselves?
所以，如果别人的触摸能让我们发痒，为什么我们不能挠痒自己呢?
Much of the explanation for this question is still unknown, but research has shown that the brain is trained to know what to feel when a person moves or performs any function.
对于这个问题还没有太多的解释，但研究表明，大脑受过训练，知道当一个人移动或执行任何功能时会有什么感觉。
We aren't aware of a lot of the sensations generated by our movements.
我们对自己的动作产生的许多感觉都没有意识。
For example, you probably don't pay much attention to your vocal cords（声带） when you speak.
例如，当你说话的时候，你可能不会太注意你的声带。
For the same reason, we can't tickle ourselves. If we grab our sides in an attempt to tickle ourselves, our brain anticipates this contact from the hands and prepares itself for it.
出于同样的原因，我们不能挠自己痒痒。如果我们抓着自己的身体侧面试图挠痒痒，我们的大脑就会预料到手的接触，并为此做好准备。
By taking away the feeling of unease and panic, the body no longer responds the same as it would if someone else were to tickle us.
通过消除不安和恐慌的感觉，身体的反应就不再像别人挠我们痒痒时一样。
