英語聽力文摘 測謊儀

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https://online2.tingclass.net/lesson/shi0529/0007/7643/272.mp3

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Lying to a Machine

不說謊的人覺得它很神秘，說謊的人覺得它很可怕，這就是神奇的測謊儀。面對不斷攀升的犯罪，善良的人們總是期望借助科學(xué)的靈丹妙藥，將所有犯罪分子手到擒來。測謊技術(shù)的推廣者們正在說服人們相信，測謊儀就是這種靈丹妙藥?，F(xiàn)代科學(xué)證實(shí)，人在說謊時生理上的確發(fā)生著一些變化，有一些肉眼可以觀察到，如出現(xiàn)抓耳撓腮、腿腳抖動等一系列不自然的人體動作。還有一些生理變化是不易察覺的，如：呼吸速率和血容量異常，出現(xiàn)呼吸抑制和屏息;脈搏加快，血壓升高，血輸出量增加及成分變化，導(dǎo)致面部、頸部皮膚明顯蒼白或發(fā)紅等等。這一切都逃不過測謊儀的“眼睛”.據(jù)測謊專家介紹：測謊一般是從三個方面測定一個人的生理變化，即脈搏、呼吸和皮膚電阻(簡稱“皮電”)。其中，皮電最敏感，是測謊的主要根據(jù)，通常情況下就是它“出賣”了你心里的秘密。目前全國已有不少城市把測謊儀引入到公安、司法界。

In an ideal world, a lie detector machine would measure some involuntary response which everyone has when they lie, but not when they tell the truth. Unfortunately, there is no such response and, because of this, no such thing as a perfect lie detector. The so-called lie detector tests you’ve heard of are usually polygraph tests. How does this test work, and how accurate is it?

A polygraph generally measures four things. Electrodes on your palm measure how much you sweat. A rubber tube(橡皮管) strapped around your chest detects changes in breathing. A blood pressure cuff measures both pulse and blood pressure.

During the course of the test, the examiner usually asks about a dozen questions. Most of these are neutral–like “What is your name?”–but mixed in are the important questions–”Did you kill your wife?” for example. In theory, if a subject lies on an important question, his polygraph response will be different from the truthful responses to the neutral questions. Does this really work? It’s true that a polygraph can measure emotional stress, and it’s also true that most people have greater emotional stress when they lie. Unfortunately, many people are likely to have an emotional response to the important question, whether they lie or not. After all, “Did you kill your wife?” is more emotionally charged than “What’s your name?” This effect is so great, one study has shown that you’ve got a fifty-fifty chance of failing a polygraph test, even if you’re innocent! Because of these odds, lie detector tests are not allowed as evidence in court cases(訴訟案件).