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Do lie detectors lie?

Does the polygraph, in the hands of a trained, competent individual really allow the operator to detect deception on the part of the person being tested?  Well, yes and no. Try betting your life or your career on that one!

In the movie “Meet the Parents,” prospective groom Ben Stiller is first interrogated and then polygraphed by his soon to be father-in-law and former CIA spy catcher, Robert De Niro. He then provides the details of Stiller’s life to the prospective bride, in this case De Niro’s daughter.  De Niro’s character was said to be a human lie detector, although he used a conventional (and now outdated) analog polygraph instrument.

Early attempts at figuring out the truth
Long before modern day polygraphs existed, the ancients still had to deal with lies and liars, and their courts had to discern between truthfulness and falsehoods. Trial by ordeal became the order of the day and the “scientific” method of determining truth. 

There were really three original ways of playing “Truth or Consequence”:

  1. Trial by fire— this requires the person being tested to walk barefoot over red hot iron. If they survived that and if their wounds healed after three days, they were considered innocent.  
  2. Trial by ordeal— the person being tested to plunge his or her arm into boiling water. If they had no blisters, they were assumed to be innocent. A variant on the water theme has the subject of the trial thrown into a river. If he sank he was considered innocent.  (Question: What if he sank and wasn’t recovered— innocent or guilty?) 
  3. Last is a somewhat more gentle method to determine truth from fiction: eating food containing a feather. If he choked, you were assumed guilty. This was long before the Heimlich maneuver, therefore if you choked, you might also be dead!

The earliest recorded attempt to invent a machine that separated truth from fiction was in 1895, but it was not until 1915 that a device was developed that established the correlation of blood pressure and respiratory changes with lying.

In 1921, an instrument capable of continuously recording blood pressure, respiration, and pulse rate was devised, followed by the first polygraph in 1926. Later versions have followed, but these machines still rely on the premise that there is a correlation between truth, lies, and body response.

How it works
A polygraph does not really separate truth from lies; or the honest from the liar. It simply provides information concerning any change in physiological response in areas such as respiration, heartbeat and blood pressure, this while the person being tested undergoes questioning. 

As a retired FBI agent, I don’t want to take anything away from my former law enforcement colleagues who practice the art (vs. science) of detecting truth, but I have been less than confident in the statistical success rate of the polygraph, having seen killers “pass” the test, and honest people “fail.”

You see, the prevailing theory behind the polygraph is that when someone tells a lie, they become nervous about their lies and their nervousness causes changes that can be noted in their breathing, their heartbeat, their perspiration and their blood pressure.  An initial baseline is established by asking questions of the person being tested whose correct answers are known to the polygraph operator (or forensic psychophysiologist).  Deviation from the known baseline for truthful answers is then taken as an indication of deception.

But what about psychopaths, sociopaths or just damn good liars?  If the old adage is correct, i.e., “If you believe it yourself it then passes as truth,” or if you have learned to control of your bodily reactions, why can’t you “pass” a lie detector test even if you are “lying?”

And what about the opposite: What if you are completely innocent but nervous, angry, sad, embarrassed or just fearful of a test whose results may affect your entire life?  Or what if you have a cold, a muscular problem, a headache, or if you’re simply constipated?  Can these purely non-voluntary bodily symptoms or conditions affect the physiological changes that are being measured against “the truth baseline?”  And what if you are nervous?  Is the nervousness due to the fact that you know you’ve done something wrong and may get found out by the polygraph, or are you simply nervous for any number of other reasons— all totally unrelated to your complicity in some suggested criminal act?

The ACLU, an organization with which I do not normally side, supported the passage of the 1988 Employee Polygraph Protection Act that outlawed the use of the polygraph “for the purpose of rendering a diagnostic opinion regarding the honesty or dishonesty of an individual.” 

Does the polygraph, in the hands of a trained, competent individual really allow the operator to detect deception on the part of the person being tested?  Well, yes and no. Try betting your life or your career on that one!      

The concept scares people into the truth
Many agencies rely on the esoteric technology factor in their use of the polygraph. By this, the polygraph machine looks high tech, the person administering the test appears professional, well-dressed and highly-trained, and you are told before your test that you may as well tell the truth because the operator will know if you don’t.  If you believe that in the war between man and machine that the machines will always win, then you may as well confess, or tell what you’re hiding. You’ve already lost, the machine is omnipotent and you’re not.  Case closed, “book’em Danno.”  After all, the so-called reasoning goes, “The innocent have nothing to hide, so take the test if you’re innocent.”  Go ahead; “take the plunge” so to speak.

If the test says you’re deceptive and you aren’t—or even if you are being deceptive— it’s still your word against the machine, and the operator’s interpretation of the data gathered by the machine. 

But here is where the real value of the polygraph comes in.  Not the bells, whistles, lights, gauges, and straps on your body, but the interview skills of the polygraph operator. If he or she has been able to convince you of the state of the art technology that is wrapped up in their polygraph machine, and if their interviewing techniques both put you at ease and/or otherwise facilitate your “truthful” response (even if such is to your detriment), then the operator and his machine have ultimately gotten to the truth.  They’ve made a believer out of you and you’ve rolled over and told them what they want to know. 

Then the end must justify the means, right?

Guilty until proven innocent?
About six years ago, various agencies in the Federal Government, including the Department of Energy (DOE), became concerned about classified information that was walking Aldrich Ames-style out of the secret safes in the U.S. and into the hands of friendly or less than friendly foreign governments.  The DOE wanted to test 10,000 to 20,000 of its employees and contractors with clearances to determine who was providing classified information to those who shouldn’t have it.  Congress approved the money to conduct these tests, but added a caveat; have the National Academy of Sciences (NAS) test polygraphs to see if they really work.  Three years later the NAS provided its report, suggesting in part that as currently used, the polygraph had serious limitations including the innocent being falsely judged to be deceptive and the guilty escaping undetected (like the CIA’s Ames and his associates).

Law enforcement and the media many times appear to suggest that we are guilty until proven innocent, and that innocence can ultimately be determined by today’s trial by ordeal— the modern polygraph. Well, Pinocchio’s nose didn’t really grow when he lied, and liars don’t always fail polygraph examinations, but the innocent can become embroiled in the controversy surrounding the use of lie detectors. They can have their veracity forever questioned because of some emotional response that a machine and its human handler finds to be off the base line.

Former President Richard Nixon once said, “I don’t know anything about lie detectors other than they scare the hell out of people.” History has shown that Mr. Nixon had legitimate reasons to be scared of polygraphs, and such may be the only true value in administering a polygraph examination.

If you apply for certain government jobs, if you are a suspect in a crime, or if, God forbid, your child or another family member is kidnapped, etc., you will probably be asked to take a polygraph test. Should this time come, be prepared to stand your ground, state your case, and decide wisely if such a “test” is in your best interest. Your reputation, your livelihood and your very future may depend on your response.

Be safe!

Clint Van Zandt is an MSNBC analyst. He is the founder and president of Inc. Van Zandt and his associates also developed , a Website dedicated "to develop, evaluate, and disseminate information to help prepare and inform individuals concerning personal and family security issues." During his 25-year career in the FBI, Van Zandt was a supervisor in the FBI's internationally renowned Behavioral Science Unit at the FBI Academy in Quantico, Virginia. He was also the FBI's Chief Hostage Negotiator and was the leader of the analytical team tasked with identifying the "Unabomber."