Liar, Liar? Easier Said Than Seen
辨識說謊者？說易行難
By John Tierney

Like most people, airport security screeners like to think they can read body language. In the United States, the Transportation Security Administration has spent some $1 billion training thousands of “behavior detection officers” to look for facial expressions and other nonverbal clues that would identify terrorists.
機場安全審查員跟多數人一樣，自認能解讀肢體語言。美國運輸安全管理局（TSA）約花了10億美元訓練數以千計的「行為偵查官」，讓他們能靠面部表情和其他非口語線索揪出恐怖分子。

But critics say there’s no evidence that these efforts have stopped a single terrorist or accomplished much beyond inconveniencing tens of thousands of passengers a year. The T.S.A. seems to have fallen for a classic form of self-deception: the belief that you can read liars’ minds by watching their bodies.
然而批評者說，目前並無證據顯示這些辦法曾攔下一名恐怖分子，或者除了每年給數萬乘客帶來不便外，有何成就。TSA似乎陷入了典型的自欺欺人陷阱：相信觀察旅客的肢體就能識破他在說謊。

Most people think liars give themselves away by averting their eyes or making nervous gestures. But in scientific experiments, people do a lousy job of spotting liars. Law-enforcement officers and other presumed experts are not consistently better at it than ordinary people even though they’re more confident in their abilities.
多數人認為，說謊者會因避免與人對視或姿態緊張而現形。但在科學實驗中人們辨識說謊者的功夫很差。執法官員及其他所謂專家儘管信心較強，卻非必然比常人高明。

“There’s an illusion of insight that comes from looking at a person’s body,” says Nicholas Epley, a professor of behavioral science at the University of Chicago. “Body language speaks to us, but only in whispers.”
芝加哥大學行為科學教授伊普雷說：「人們對於觀察肢體可產生的洞察力有種錯覺。肢體語言會向我們說話，但說的可是悄悄話。」

The T.S.A. program was reviewed last year by the federal government’s Government Accountability Office, which recommended cutting funds for it because there was no proof of its effectiveness. That recommendation was based on the meager results of the program as well as a survey of the scientific literature by the psychologists Charles F. Bond Jr. and Bella M. DePaulo, who analyzed more than 200 studies.
美國政府責任署去年審核TSA的訓練計畫，建議刪減經費，因為並無證據顯示其有效。此一建議根據的是訓練計畫的貧乏成果，以及心理學家龐德和貝拉．狄保洛分析200多項研究取得的科學文獻調查結果。

In those studies, people correctly identified liars only 47 percent of the time. Their accuracy rate was higher, 61 percent, when it came to spotting truth tellers, but that still left their overall average, 54 percent, only slightly better than chance.
在那些研究中，人們指認出說謊者的比率是47%，雖然指認說實話者的比率較高，達61%；平均正確率仍僅54%，只比純碰運氣略高。

“The common-sense notion that liars betray themselves through body language appears to be little more than a cultural fiction,” says Maria Hartwig, a psychologist at John Jay College of Criminal Justice in New York City. Researchers have found that the best clues to deceit are verbal – liars tend to be less forthcoming and tell less compelling stories.
紐約市約翰傑刑事司法學院心理學家瑪麗亞．哈特威格說：「騙子會透過肢體語言洩底的常識概念，似乎只是一種文化假象。」研究發現辨識欺騙的最佳線索是言語，騙子多半說話不那麼乾脆，說的故事也往往不那麼令人信服。

One technique that has been taught to law-enforcement officers is to watch the upward eye movements of people as they talk. This is based on a theory from believers that people tend to glance upward to their right when lying, and upward to the left when telling the truth.
教給執法官員的一個技巧是，觀察人們說話時眼神向上的動作。相信這一套的人根據的理論是，說謊時眼神往往朝右上方看，說實話時則看左上方。

But this theory didn’t hold up when it was tested by a team of British and North American psychologists. They found no pattern in the upward eye movements of liars and truth tellers.
但這套理論並未通過一個英國及北美心理學家團隊的測試，他們發現，說謊和說實話時眼神向上動並無固定模式。

“There is no Pinocchio’s nose – no one cue that will always accompany deception,” says an author of the eye-movement study, Leanne ten Brinke, of the University of California, Berkeley.
柏克萊加州大學的蓮恩．布里克參與前述眼動研究，她說：「現實中並不存在童話《木偶奇遇記》主角皮諾丘那種一說謊就變長的鼻子，沒有哪個線索必定伴隨著欺騙。」

She and others argue that it may nonetheless be possible to detect certain kinds of “high stakes” lies by looking for an array of body cues. Stephen Porter of the University of British Columbia says the poor success rate in studies is caused partly by the limitations of laboratory experiments in which subjects are often asked to lie about things that don’t matter to them.
蓮恩．布里克等人說，尋找一整套身體線索，或可偵測出某種「可能性很高的」謊言。英屬哥倫比亞大學的波特說，研究中指認說謊者正確率僅47% 與實驗的限制不無關係，實驗要求受試者針對與自身無關的事說謊。

Last year, psychologists at the University of British Columbia trained professionals in forensics to look for facial expressions and other signs of stress or inconsistency in someone telling a story. Then these professionals looked at news footage of people pleading for the return of a missing relative.
英屬哥倫比亞大學的心理學家去年訓練了幾位專業鑑識人員，在人們說故事時尋找面部表情與其他緊張或前後不一的跡象。然後他們觀看他人懇求釋放失蹤親屬的新聞畫面。

Some of the pleaders were sincere, but others were lying (as eventually revealed by evidence that they had already murdered the relative). The trained professionals were able to identify the liars with an 80 percent accuracy rate.
有些懇求者頗為真誠，其他則在撒謊（最終證據顯示撒謊者殺害了那名親屬）。受過訓的專業人員認出說謊者正確率為80%。

That’s an impressive record, but it’s only one experiment, and many researchers question how reliably these techniques can be applied in the real world.
這項紀錄頗為可觀，卻只是一項實驗，許多研究人員質疑，這種技巧用在真實世界能有多可靠。

Why do we intuitively believe we can read body language? After writing a book on the topic, Dr. Epley has an explanation.
我們為什麼憑著直覺就相信自己可以解讀肢體語言？就此事寫了本書後伊普雷提出了解釋。

“When you’re lying or cheating, you know it and feel guilty, and it feels to you as if your emotions must be leaking out through your body language,” he says. “You have an illusion that your emotions are more transparent than they actually are, and so you assume others are more transparent than they actually are, too.”
他說：「當你說謊行騙時，你心知肚明且有罪惡感，覺得你的感受一定會透過身體語言洩漏出來。這時你有錯覺，以為自己的情緒比實際上更透明，也因此認定其他人的感受也比實際上更透明。」

原文參照：
http://www.nytimes.com/2014/03/25/science/in-airport-screening-body-language-is-faulted-as-behavior-sleuth.html

Interactive Multimedia：Can You Spot the Liar?
Subjects in a study on body language and lying were asked several general questions — and then told off camera to lie or tell the truth when answering. Can you tell truth from falsehood?
http://www.nytimes.com/interactive/2014/03/21/science/can-you-spot-the-liar.htm

2014-04-08聯合報/G5版/UNITEDDAILYNEWS 馮克芸譯 原文參見紐時週報十版上