国家地理:Lie Detector 测谎仪的奥秘

It might be the cheeks flushing with embarrassment or a voice choking with emotion. Our physical reactions can reveal what we truly feel. And some think they can show when someone's lying.
Typically when a person tells a lie, they begin to sweat. I'm sure we've all seen the 1940s and 50s interrogation movies where the person in the hot seat has a sweaty brow or a sweaty upper lip or perhaps sweat dripping down from their sideburns.
"All right, if you lean forward in the chair, put your arms up (in) front of you, like you're gonna dive into a swimming pool. Put this around your stomach. "
Jack Trimarco uses physical sensations to probe for truth. His primary tool? The lie detector, or polygraph.
"This cuff is just like the one of the doctor."
Polygraph, its work's very similar to any other biofeedback instrument. It simply records deviations from a person's physiological norm, such as someone's blood pressure going up and then coming back down, or perhaps a decrease or an increase in pulse rate, or sweat pore activity.
"Are you sometimes known as Bobbie?"
"Yes."
A polygraph examiner knows what to look for when questioning someone.
"D o you intend to be completely truthful with me?"
"Yes."
Any deviation from normal could signal deception. Our body can give us away.
"And are you sure that I won't try to trick you on this test?"
"Yes."
We may think we're being cool, but when we're stressed, our network of nerves starts to prepare our body for action as if it's under attack. It's a response that harks back to our ancient ancestors -- fight or flight.
It starts by triggering your stress hormone -- adrenalin. Your heart rate increases to pump more blood to your muscles as if you were about to go into battle. Your breathing deepens as vital oxygen reaches your muscles. And you begin to sweat -- the body cools so that you won't overheat when rushed into action. The brain won't let us stop the survival strategy. These basic nervous functions are automatic. That's why a polygraph can often uncover a liar.
1. hot seat: (n., slang) 1. The electric chair used to cause death by electrocution in legal executions.
(informal ) 2.A position in which you can easily get into trouble.
e.g. A judge in a beauty contest is on the hot seat.
2. sideburns: pl.n.(复数名词)Growths of hair down the sides of a man's face in front of the ears, especially when worn with the rest of the beard shaved off. 连鬓胡子：在耳朵前面沿着脸侧部向下生长的毛发，尤指胡子刮去之后留下的残茬
3. hark back: To return to a previous point, as in a narrative.
e.g. he keeps harking back to his music-hall days
4. adrenalin: [生化]肾上腺素
5. rush sb into sth
参考中文翻译：
可能由于尴尬脸会变红，或者由于情绪激动声音会颤抖。我们的身体反应会揭示出我们的真实感受。有人说当有人撒谎时也可以体现出来。
特别是当一个人说谎时，就会开始流汗。我确定我们都看过四五十年代的电影，当犯人坐在电椅上接受审讯时，总是会额头冒汗，或者上唇出汗，或者，汗珠从胡子上滴下来。
“对，像坐在椅子上一样身体前倾，胳膊放在身前，就好像准备跳入游泳池中的动作。把这个放在胃部周围。”
Jack Trimarco 利用身体的反应来探寻真相。他的主要工具是什么?测谎仪。
“这就像是医生的探测仪一样的。”
测谎仪的工作原理像其他的身体反馈仪器一样。它简单的记录某项身体指标的偏差，比如某人的血压突然升高然后回落，或者脉搏加快或者降低，或者汗腺活动。
“你有时候是不是会被认作Bobbie?”
“是的。”
测谎仪检测者知道问某人问题时应该注意哪些方面。
“你打算对我讲真话吗?”
“是的。”
身体反应的任何偏差都会发出欺骗信号。我们的身体会出卖我们。
“你是否确信在这场测试中我不会戏弄你?”
“是的。”
或许我们认为自己很平静。但是当我们遇到压力时，我们的神经系统使你的身体处于准备好接受袭击的状态。这是可以追溯到我们的祖先的原始反应——还击或逃跑。
它从触发你的压力荷尔蒙——肾上腺素开始。心率增加，向肌肉中泵入更多血液，就好象时刻准备战斗一样。呼吸加重，更多的氧气进入血液中。你开始流汗——体温下降，因此当你仓促行动的时候不会流汗过多。大脑不会让我们停止生存策略。这些基本的神经功能是无意识的。这就是测谎仪能找出说谎者的原因。