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Taking the Mystery Out of the Polygraph Test

Taking the Mystery Out of the Polygraph Test

Sergeant Betsy Brantner Smith

A polygraph exam is often a “make or break” part of the police testing process, but it’s often difficult to prepare for and even understand. As Richard Nixon said “I don’t know anything about lie detectors other than they scare the hell out of people!” Polygraph testing is used far more in government pre-employment processes than in the private sector. In recognition of this, the APA Research Center at Michigan State University surveyed 699 police executives from some of the largest police agencies in the United States to determine the extent of, and conditions in which, polygraph testing is being used for pre-employment screening (this survey excluded federal agencies). The major results of the survey showed that of the respondents 62% had an active polygraph screening program, 31% did not and 7% had discontinued polygraph screening. Admittedly, polygraphy is not an exact science, but if it’s going to be a part of your next law enforcement employment process, take the time to learn the basics.

The polygraph, or “lie detector” is an instrument that measures and records physiological responses like breathing rate, pulse, blood pressure and perspiration. The underlying theory of the polygraph is that when people lie they get measurably nervous about lying. Its name stems from “poly” for the multiple sensors used and “graph” for a single strip of moving paper that records information, although most polygraph examiners now use computer images instead of analog instrumentation. A polygraph examiner is generally a highly trained interrogator as well as the technical operator of the devise and will use their experience in addition to the machine to detect your truthfulness.

One of the most intimidating parts of the polygraph exam is being attached to the sensors that will collect physiological data from at least three systems in the human body. After being attached to four to six sensors, your polygraph exam will likely start with a pre-test interview to gain some preliminary information which will later be used for control questions; this is called the “Control Question Test,” or CQT. Often, the examiner may ask you to deliberately lie several times to test your responses; this is a “Directed Lie Test,” the DLT. They may also ask “probable-lie” questions, such as “have you ever stolen anything?” (even the most honest person has “stolen” a pen from work or a candy bar from their little sister or some other “theft” that concerns them enough to show a stress response when answering).

Finally, they may use the “Guilty Knowledge Test,” GKT, a test that compares physiological responses to multiple-choice type questions about particular facts that only the examiner and you would know. The majority of American Psychological Association members surveyed think that the GKT is the most accurate of these tests and consider it “a promising forensic tool.” However, polygraph testing is still largely controversial in the U.S., so why do so many police agencies use it?

In the Michigan State survey the great majority of the agencies using polygraphs indicate that lie detectors reveal information that cannot be obtained by other selection methods. They also stated that polygraph testing makes it easier to establish background information, that it deters undesirable applicants, and that it is faster than other methods of selection. About half of the agencies using polygraph testing for sworn positions also use it for non-sworn employment, such as dispatchers, records clerks, and even secretarial personnel.

CIA operative-turned-spy Aldrich Ames, convicted in 1994 of spying for the Soviet Union, famously passed several lie detector tests by allegedly being told by his Soviet handler to "Get a good night’s sleep, and rest, and go into the test rested and relaxed. Be nice to the polygraph examiner, develop a rapport, and be cooperative and try to maintain your calm.” Often subjects are also told to try and control their breathing or artificially raise their heart rate during control questions (IE: thinking about a scary movie scene even while you are telling the truth), but the bottom line is this: tell the truth.

Come to your polygraph exam well-rested and well-fed, dress appropriately, and answer the questions truthfully to the best of your ability. Most police agencies don’t expect you have lead a perfect life, but they do expect you to be truthful. After all, law enforcement is profession of honor and integrity. Good luck.

  • Photo_user_blank_big


    over 5 years ago


    Some law enforcement agencies in California have automatic disqualifiers, such as prior drug use. A friend of mine had informed me that he had experimented with LSD once when he was in high school. He was told that by the first department he had applied to that any use of an hallucigin would result in an automatic disqualification with that department. Therefore, he lied because he felt he had no choice. He passed the polygraph and was hired with that department. He has since relocated and transferred to another department where he passed the polygraph a second time. He felt he needed to be consistent since many departments will disqualify an applicant for use of an hallucigin. He is currently employed, though is seeking employment elsewhere due to possible layoffs within the department he currently worsk for (city budget issues). He recently applied to another department and took a polygraph for the 3rd time. During the post-poly, the examiner shared the results with him. The examiner informed him that he sensed deception on the illicit drug question. He finally confessed and informed the examiner that he lied because had used LSD when he was in high school. This was the only thing that may prevent him from getting hired with this department, though they have not gave him an answer just yet. Now to the question? Does an agency have the right or are they mandated to inform the current police department that my friend is employed by of this incident. He also did not reveal his LSD use to his current employer, though had passed the poly with his current employer. He said he had no choice but to lie since some departments disqualify applicants if they ever used an hallucigon. He felt he needed to be consistent, and is torn by this.

  • P_308_max50


    over 5 years ago


    Polygraphs are snake oil programs. I can not believe we are this insane in the 21st century. Aldredge Ames took a polygraph every year for at least 12 years in the CIA. He was asked ...."Are you selling us out? Are you stabbing us in the back?' He answered NO! "Of course not !!! Up until the day he envoked his 5th ammendment rights. He is now doing life for selling us out and stabbing every citizen in the USA in the back. The Central Intelligence Agency has the best graph ops in the world. It is wasted money. I won't bore you with the triple test 60 minutes did on Pgraph ops. Except to tell you 3 of the best agencies in New York City were hired to find a stolen Nikon camera at CBS HQ. Each time the ops. guy asked who was suspected of stealing the camera. A name was given before testing began Each and every time That Was The PERP!!! according to the operators....Just one problem......No camera was stolen. All the companies hired flunked. Snake oil used by sociopaths. Grow up and join the real human race some day.....

  • Photo_user_blank_big


    over 5 years ago


    Great Info on polygraphs!

  • Photo_user_blank_big


    over 5 years ago



  • Photo_user_blank_big


    over 5 years ago

    Polygraphs are effective machines, the breakdown process is usually due to the polygrapher. The few instances I've seen where its been an issue, the chink in the armor was human error, either in the operation or the reading of the results. Nothing is absolute.

  • Larry_apache_dist_13_max50


    over 5 years ago


    Well times have changed I have had 4 pre-employment polygraphs and 1 internal affairs polygraph with the old up and down needle instrument and 3 pre-employment with the new computer enhanced polygraph. Every time they have made me nervous as hell, but with a good polygraph examiner they will work with problem questions and frame the question to put you at ease. Just the truth and nothing but the truth !!!!!!!!

  • Photo_user_blank_big


    over 5 years ago

    I think they are right on target. Using them in pre-employment I'm not for. A department can do a good background check- w/out making the applicants feel like they are on the hook for something. My dept. did a better back ground check on me, than the military did for clearance.

  • Profile_picture_max50


    over 5 years ago


    Polygraph is actually very accurate... 96% accurate, if used properly.... nervousness is usually taken into account and if you are nervous you will be nervous on ALL questions NOT just one or two ... so your nervousness should show across the board. ... unless your not being truthful. I have been administering polygraphs a awhile now and it is very interesting on how and why it works... no voodoo, no magic ... just people who think they can beat it and not tell the truth... it is actually pretty simple ... what is really scarry about it... tell the truth and really not anything to be scared about.. And yesI have taken 3 myself. I thnk they are a great tool for investigations and they are up and coming in police investigations, they can help you.....

  • Fantasy_swords_sword_of_darkness__uc1120b_1632_max50


    over 5 years ago


    i don't believe in the polygraph tests because they are never reliable. they make people feel nervous and then say they are lying...that is not how it is supposed to be. the machine is crap and i am sorry for all the officers and people that have been called liars when they are not.

  • Quagmire-mugshot_max600_max50


    over 5 years ago


    Polygraphs are Vodoo Science. Nothing but a scare tactic

  • Photo_user_blank_big


    over 5 years ago


    Hello, My name is robert zuniga, I tell my whole name because i have NOTHING to hide, and i want to share this message with the world if possible. I voluntarly took a polygraph to clear my name from an incident that happened to me at a job that i was employed at for a armored car service! I was wrongfully terminated because money had been missing on our route that my partner an i were on. I will not go into details for it is still under investigation, I took the polygraph like i said to 1) Clear my name and 2) To fully cooperate with this investigation and to help and aid in finding the money that is still missing?? Well needless to say the polygraph determined deception, I don't know why???? I have read all the comments in this article and on the day that i took the polygraph i did not eat i work two jobs so i was tired, But i was relaxed actually relieved is a better word, for finnally getting a chance to clear my name and i do not know WHY it registered deception?? I was grilled by the examiner after he went over the results as he was trying to get me to confess to something i did NOT do. I am an upstanding citizen and i PRIDE myself in telling the TRUTH, and i can carry on an intelligent conversation with anyone and often help people who are in need and i can figure just about any problem or at least give a answer to help in any situation, But for the life of me people i am dumbfounded by why this happened to me? After i left the building where i took the test i sat on the steps in tears and going over in my mind how truthful i was on this and every exam i have ever taken!! This is only my third exam ever in my life the other two i passed for employment positions, I always believed in polygraph tests until now!!! I am writing this for someone out there to help me in answering my questions of how this could happen, besides the comments i already have read. Two things i know for sure is I am telling the truth and my Higher Power whom i choose to call god knows i am telling the truth, I will gladly take it over again although i won't be so calm this time for fear that was put in me from this test, I would be fully confident because again i am telling the truth, But i am skeptical of these tests now..Heck i even shared with the examiner something only few people know about that is NOT directed to the investigation but what i did in my life so i could get a full clear conscience before answering all questions, So to who ever is out there thank you for reading this and for letting me vent some frustration off my chest, cause instead of sulking or crawling into a hole i choose to still fight to clear my name of any wrongdoing..Have a great and fantastic

  • Photo_user_blank_big


    over 5 years ago


    I told the truth on the polygraph test but the "physiological responses" to those questions indicated I'd been lying. They are not accurate and reveal false positives all the time. Some people are just more nervous than others at being asked very freaky questions like "Have you ever had sex with a dead person?"

    The only thing those instruments measure is who's more nervous than others.

  • Tahoe_047_max50


    over 5 years ago


    I am a polygraph examiner and police officer. Trust me when I say that you want your fellow officers polygraphed in the hiring process. The information that is obtained from these exams tell an unmeasureable amount about a persons integrity. As far as preparing for the exam...tell the truth. You are NOT expected to be perfect going into a polygraph. We know that you have, as have everyone, made mistakes. We just want to see if you have the ability to be honest about it. By the way you can not beat a polygraph test, only the unexperienced examiner, and besides if you have to try and beat it you obviously have something to hide. So are you really worthy of wearing the badge?

  • 177601787v32_480x480_front_max50


    over 5 years ago



  • Advance_seal_max50


    over 5 years ago


    Snake Oil!!!

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