Use of lie detectors must be reconsidered


A polygraph test is usually considered an accurate way to detect whether someone is lying, right?

And since 15 federal agencies — including the FBI and CIA — and many police departments and sheriff’s offices across the country rely on polygraph testing for hiring and criminal investigations, it must be correct just about all the time, if not all the time?

Bzzzzzt! Wrong.

A technical glitch in one of the most popular polygraphs, the LX4000, has produced errors in the computerized measurements of sweat. This isn’t a new revelation. Polygraphers first noticed the problem a decade ago, but the information wasn’t known by many government agencies and others.

Wow. How many innocent people have gone to jail, how many people have lost jobs and how many spies escaped because of this problem?

McClatchy Newspapers has been investigating this and other concerns regarding polygraphs, which are commonly called lie detectors.

The newspaper chain, which owns the Tri-City Herald, The Olympian and 28 other daily newspapers, did not try to answer the hypothetical question affected by the glitch.

But its reporters found the use of lie detectors in this country widespread even though the results are far from 100 percent correct.

Scientists have questioned whether polygraphers can accurately identify lies by interpreting measurements of blood pressure, sweat activity and respiration, according to the McClatchy report. Yet, the individuals administering the tests say they rely on the measurements to be accurate for their daily, high-stakes decisions about lives.

“We are talking about using a procedure that has a very weak scientific foundation and making it worse,” said William Iacono, a University of Minnesota psychology professor who has researched polygraph testing. “ ... They might as well be flipping a coin.”

Even some supporters of polygraph tests conceded the accuracy of the tests can be between 85 percent and 95 percent.

Those would be fantastic percentages for buying lottery tickets, but horrifying if your future and freedom were on the line.

The far-less-than-certain results are likely the reason most private employers haven’t used polygraphs for the past 25 years and lie detector results are not admissible as evidence in trials.

McClatchy, however, found that more than 70,000 people are polygraphed each year for federal jobs and most cannot challenge the results in court nor can they allege abusive tactics.

Adding to the list of problems is that unlike devices such as those used to calculate blood alcohol content for suspected drunken drivers, lie detectors do not have to be regularly tested and recalibrated.

Clearly, changes need to be made in federal job screening and law enforcement.

The entire McClatchy series on polygraphs can be found here.


Use the comment form below to begin a discussion about this content.

Sign in to comment

Click here to sign in