Polygraphs Are Not Reliable in Detecting Lies

There are many flaws

 
People are always searching for the supreme truth.

But are the polygraphs a reliable tool in detecting lies?

It seems that those who know how to lie have little to fear, as they can control their emotions. Instead, the victims could be the truthful people.

Polygraphs were not developed as lie detectors; they just track down physiological expressions linked to lying in some people, like racing heart and sweaty fingers and everything's in the hand of the subjective interpretation of an examiner, fact that may lead to errors.

It's impossible to make the difference between the anxiety of "I'm going to be caught" and "they're going to believe that I'm lying when I'm not."

The polygraph is just a medical device that registers respiratory rate, heart rate, blood pressure and electrodermal response, and minute changes in perspiration, normally from the fingertips.

The problem stands by no means in the accuracy of the apparatus. A 2002 research made by National Academy of Sciences 2002 reached the conclusion that "polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection. The polygraph rests on weak scientific underpinnings despite nearly a century of study." "The high incidence of false positives-a truthful response determined erroneously to be a lie-makes the polygraph useless," the Academy said.

The modern polygraphs could detect 8 out of 10 spies employed at a national atomic laboratory with 10,000 hypothetical workers. In this case, the polygraph would detect 1,600 innocent guilty employees, translated to 1,600 ruined careers. But the government officials disliked the results, as they still employ the polygraph in the war on terrorism.

About 8,000 employees at the Los Alamos National Laboratory have been announced they will be checked randomly with the polygraph.

Scientists warn that the polygraphs of the future should involve brain scanning.

A study at Temple University in Philadelphia discovered brain areas involved in lying and which can be monitored with functional magnetic resonance imaging (fMRI) scans.

But if for some people lies are "their truths", even this method could be flawed.

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By    24 May 2007, 11:41 GMT