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What is a polygraph examination?

A polygraph instrument, or lie detector examination might best be described as a truth verifica­tion examination or test.  While all eminently qualified polygraph experts must always remain neutral and not be swayed by someone's appearance, age, gender or personality, each examiner must be doing everything within their power to influence the person taking the test to have a fa­vorable result.  Anyone and everyone can pass the examination simply by being completely truthful about the issue being examined, and do so during the pre-test polygraph interview.  Irrespective of what the person taking the test may have done, by being truthful during the pre-test interview, it guarantees their successes in passing the examination.  For example, if someone was being tested for a theft at his or her place of business, and they discuss this with the examiner, one of the relevant test questions might be, "Other than what you discussed with me before this test, have you stolen any more of the missing money or product?"  It is our experience that since a wider margin of those taking the polygraph test have favorable truthful responses, it might be best to refer to the examination as a "Truth Detector" as opposed to 'Lie Detector."  The word polygraph is from the Latin, "Many Writings."  A modern day polygraph instrument evaluates multiple physiological responses, thus, "Poly," as in "Many" writings, graph.

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Should I take a polygraph examination?

First, and foremost, all tests must be taken on a voluntary basis.  No person should be intimi­dated or coerced into taking such an examination.  If you have been threatened to participate in a polygraph, (lie detector) test, there is a possibility that it could have a negative effect on the in­terpretation of the charts.  At Vision Investigative Services, we will not knowingly accept an ap­plicant for testing if we believe they have be threatened, in any way, into undergoing the poly­graph process.  Our policy is absolute.  There are no exceptions.  Of course, being asked to take this test may not be a comfortable issue, yet it does not necessarily rise to the level of coer­cion.  More often than not, those who do participate in testing do so because they want to clear their good name of some issue, whatever that issue may be, and regardless of how odious the subject matter under consideration.  Yet, we do understand that occasionally some people will offer to take the test, simply believing that the mere taking of the test is indicative of innocence and truthfulness.  Expert examiners will make that determination on the basis of your responses on the test and rely on each of the instrument's components, much the way that physicians rely of them in a diagno­sis of your health.  Some of the polygraph recording devices provide either similar, or identical readings as medical equipment used in the diagnosis of a patient.

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What does the polygraph procedure involve?

Once a person has scheduled an examination, a block of time is allocated to properly conduct a pre-test interview, the examination itself, a possible post test interview and occasionally, the preparation of a typed report which outlines the issue under consideration, the relevant test questions, and the opinion of the expert who administered the examination.  The test itself is traditionally the component of the entire polygraph examination process that takes the least amount of time.  The purpose of the pre-test interview is to garner as much information as necessary to prepare the test ques­tions.  It also allows the examining expert the opportunity to explain the instrument itself, and to an extent, what physiology is actually being recorded.  Multiple issue tests should never be conducted.  For example, a standard series of test questions may contain many questions about a singular is­sue....such as theft, arson, fidelity or child molestation.  Yet, it would never include both issues during the same examination.  Typically, polygraph experts would ask a client to explain the general nature of the test and specific information to formulate the test questions.  Clients that require testing of mul­tiple issues should know that to accomplish this type of testing, it also requires different testing sessions, generally on different days of testing.  No compound questions should be allowed and conjunctions are never allowed.  For example, your expert would never ask a question such as "Did you rob and kill John Doe?"  The reason for not asking such a question is that if deception to that question were noted on the test tracings, the examiner would not know whether the person taking the test robbed, or killed John Doe, or did both.  We encourage all clients of Vision Investigative Services to allow our specialists to assist you in identifying the most critical issues in formulating the test question format.

The examination does not cause pain.  There can be some slight discomfort with the pressure in the blood pressure cuff, but since the actual chart time for each series of questions is typically un­der three minutes, there is usually a slight numbness or tingling as opposed to a painful expe­rience.  All test questions are reviewed with each person being tested.  Surprise questions are never allowed and we urge anyone who has agreed to participate in this testing technique to ter­minate the test should any unrevealed questions be asked during the test.  Always remember, you control whether you take this test and you may feel free to discontinue it at any time.

Any person that appears to have been drinking alcoholic beverages will be refused for testing.  Any person that appears to be physically unfit for testing because he or she has used drugs, pre­scribed or otherwise will also be rejected if the examining expert feels that they might interrupt the proper interpretation of the examination.  Of course, polygraph experts do not want you to stop taking your medication.  Taking your prescribed medication is important and does not mean that an effective and accurate test is not possible.  In almost all cases, successful completion of the test will be quite possible.  All eminently qualified examiners will be able to identify anyone who has taken drugs or narcotics for the sake of getting high, or "low" as the case may be, and your chart tracings will immediately identify whether or not  you are a suitable "subject" for testing.  It can be a very expensive mistake to take un-prescribed drugs or even prescribed medi­cation in un-prescribed and high dose levels before taking a polygraph test.  Of course, you put your health at risk, and you may have to pay for the polygraph examination even if you are deemed unsuitable for testing due to drinking or taking drugs in a dose other than specified by your phy­sicians.

Vision Investigative Services does not conduct routing screening tests for any private, corporate or police entity.  While they certainly do have some measurable and proven value, we do not be­lieve that they hold the same extremely high level of validity of other testing.  This is not to infer that some firms with great expertise cannot or should not perform these types of tests.  Our firm has always considered the amount of time that it takes to conduct the entire test as a key compo­nent and consideration for the person taking the test.  The examinations that we perform are li­mited to approximately ninety minutes for the entire interviewing and testing process.

All persons taking a polygraph/lie detector test must be provided with their test results.  Not only is it fair, in many circumstances it is illegal not to do so (Federal Polygraph Protection Act) and it allows anyone who may have deceptive responses the opportunity to correct any deficiencies and false answers.  By doing so, it allows the examiner to re-test the examinee so that they can conclude their examination with a highly favorable report.

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Who uses polygraph examination?

Three sectors of our society currently use polygraph examinations for a variety of reasons.


Individuals, families, therapists, and employers use a polygraph examination to verify statements and to find the truth in a variety of issues, including but not limited to issues involving infidelity, drug use, addictions, sex offenses, employee thefts, criminal activities, physical abuse, and other criminal activities.


The polygraph is used extensively by attorneys who wish to provide the best possible defense for their clients. Many attorneys will submit their own clients to a polygraph examination, while other will use the polygraph to verify statements made by witnesses and other parties to the liti­gation. Many polygraph examiners have a great deal of experience working with attorneys, both in private and government practice and have aided thousands of clients in preparing defenses that would otherwise have been unavailable to them. Based on the current polygraph research, the polygraph has improved its credibility with the scientific community. These standards, approved by a combined body of experts, now provide a template for the increased acceptability of polygraph test results

Contrary to popular belief, the polygraph is not per-se inadmissible in court proceedings. Admis­sibility standards are different in each jurisdiction. Some jurisdictions allow polygraph evidence, either stipulated or un-stipulated, some prohibit polygraph evidence altogether, and many others allow the judge to decide admissibility on a case-by-case basis. Polygraph tests have been used outside the courtroom in pre-trial negotiations, plea bargaining, sentence recommendations, and witness verification or impeachment.


Local Police Departments, Sheriff Offices, U.S. Military Branches and Government Agencies such as the FBI, CIA, NSA, Postal Inspectors and Department of Defense all use polygraph examinations for ap­plicant screenings, criminal investigations, and matters of national security.

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What does polygraph testing involve?

Most polygraph examinations last between one and two hours, but the examinee is only attached to the polygraph instrument for 15 to 20 minutes. There are exceptions some of which include criminal testing or screening tests. The typical polygraph examination involves three separate phases. The pre-test interview takes up most of the time. During this phase the polygraph ex­aminer completes all the miscellaneous paperwork and provides the examinee with an introduc­tion to the polygraph instrument and all components. Then the examiner and the examinee will review and thoroughly discuss the test issue (reason for the polygraph test) during which time the examinee will tell the examiner what he or she did or did not do. Prior to attaching the examinee to the polygraph instrument all test questions are reviewed with the examinee, word for word. There are no surprise or trick questions asked. During the in-test phase wherein the examinee is attached to the polygraph instrument. The examinee’s psycho-physiological responses are rec­orded as the examiner asks each question and the examinee responds with a “yes” or “no” an­swer. The same questions are repeated on either two or three separate polygraph charts. At the completion of the third chart, the chart analysis begins where the examiner analyzes and numeri­cally scores all polygraph charts to determine whether the examinee’s answers to the test ques­tion indicate truth or deception. The examinee is immediately informed of the test results and if deception is indicated, the examinee is provided with an opportunity to explain the deceptive reactions in his or her answers to the test questions.  In many cases, the examiner will administer what is commonly referred to as a "Control" test to ensure that the examinee is responsive to a spoken stimulus.  This is not a part of the actual or specific test but serves a variety of purposes including, but not limited to introducing the examinee to the process of taking the test and for balancing the subject into the instrument.  Again, even the "control test" questions will be reviewed with the per­son taking the test prior to the administration of the test itself.  Some of this may sound some­what complicated, or confusing.  Some clients tell us that it is ominous and yet, to a highly trained and tenured expert, it is routine and quite simple.  At the end of the examination, you will be asked to affix your signature and the date of the test onto the collected specimen.  This measure protects the person taking the test from having their charts confused with someone else's.  This process should always occur when taking a test on an analog instrument.  If you are taking your test on a computerized instrument, the examiner should always print the chart out and have you sign (or at least initial) each page of the chart.  Polygraph instruments are portable and even when the test­ing is being done at a facility away from the examiner's office, they should have a portable prin­ter with them which will allow them to print the chart and have you identify those charts with your signature and the date of the examination.

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Examiner qualifications. 

The purpose of polygraph academic facilities is to prepare examiners for all types of polygraph testing.  Generally, there exists some type of certification program prior to the student being cer­tified by their academic institute.  In other words, simply attending the required classes does not make anyone a complete polygraph expert.  While recently graduated students should be quite capable of all types of tests, we all know that experience is often the best teacher.  No examiner should be shunned simply due to their age, gender, or years of experience.  Many seasoned examiners would attest to the fact that they have witnessed relatively new examiners that faithfully practice what they were taught in school.  Our experience is that students that have been trained in schools certified by the American Polygraph Association generally comply with proper procedures and decorum.  Some schools that were once credentialed by the A.P.A. are no longer in existence, but many, and perhaps most of their students continue to practice their craft to this day.  Consider what the examiner has done in his career and education since graduating from their school and how many examinations he or she has conducted.  Have they been court qualified as experts at any time during their career or writ­ten any papers that were submitted for peer review.  Have they donated their time to speak at seminars, or by guest lecturing at certified schools?  Vision Investigative Services chief examiner has been a polygraph expert for over forty six years.  He served as a staff instructor at three American Polygraph Association certified polygraph training facilities.  He served two terms as the president of the California Academy of Polygraph Sciences which was a viable entity until the 1990's.  He has testified before the California Judiciary on polygraph issues.  He has lectured throughout the United States at various bar association meetings, and has lectured at Harvard University to a large group of attorney's dealing with D.U.I. investigations and related polygraph issues.  Steve Long has also been a private investigator for four decades and attributes much of his own successes in administering polygraph examinations with having the additional aptitude of extensive investigative training.  He has sponsored dozens of advanced training seminars both in polygraph testing and investigation.  He has conducted more than thirty  thousand polygraph examinations with over half of those exams being of a specific nature.  He has tested for dozens of police facilities during his career.  He now limits his testing to private testing, although occa­sionally he still conducts polygraph tests for tenured business clients.

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Can someone beat a polygraph test?

The general consensus within the polygraph profession is that, at best, someone might deceive an untrained or unskilled examiner.  The polygraph instrument itself records psycho-physiological changes or reactions occurring within the examinee’s Autonomic Nervous System as the examinee answers the polygraph test ques­tions with a “yes” or “no” answer.  The instrument does not talk and it certainly fails to take into account those who might be testing without eminent qualifications and calibrated equipment.  "Lie detectors really don't lie, people do!"  The worst that could happen would be testing with an inept examiner.  We always find it amusing when a potential client calls and their first question is, "How much is the test?"  Sadly, all too often once a price is quoted, they have no other questions such as, "Can you tell me about some of your credentials?"  Don't be fooled into thinking that if you test with an inept, or charlatan examiner that you will automatically pass simply because you are telling the truth.  Examiners that have stood the test of time have done so because they were schooled properly and have vast experience in their profession.  You might be amazed at the number of highly professional examiners, young and old, male and female, that have had to re-examine someone who first went to the cheapest examiner in the area.  In those instances, the examinee did not beat the test.....the test beat them.  This is all preventable by being selective in choosing your examiner. 

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Can nervousness cause a person to fail the test?

No. Nervousness is a constant. In other words, you cannot turn your nervousness off for one test question and then back on for the next test question. Your nervousness is present throughout the testing process. It is, in essence, the degree of nervous fluctuations within designated parameters that allow experts to identify truth and deception.  Plus, when reviewing and numerically scoring your polygraph charts, a well trained and experienced polygraph examiner can evaluate the differ­ence between a nervous reaction and a reaction caused by a deceptive answer to one of the poly­graph test questions. This is why the education, training, and experience of the polygraph ex­aminer is critical. This is not to suggest that everyone taking the test, whether it is their intent to be truthful or otherwise, will not be nervous.

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What does it mean when someone fails a polygraph test?

When a polygraph examiner concludes that deceptive reactions are observed on the polygraph charts in one or more of the examinee’s answers to the test questions, the examinee is said to have “failed” the polygraph test. Deception is indicated when the examinee’s Autonomic Nerv­ous System displays a significant and repetitive “defensive” reaction to one or more of the rele­vant test questions. Although this reaction in itself in not a “lie,” years of research has shown that 90 to 95 percent of  the examinees who display this reaction were either lying to the relevant test questions or was withholding pertinent information relating to the relevant test questions. Fre­quently, an examiner will conclude only that “the examinee cannot be excluded as a suspect” when deceptive reactions are present. It is important to note that some examinees will “fail” a polygraph test even though they are telling the literal truth, but they continue to hold back perti­nent or incriminating information from the examiner.

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Have you been told that the polygraph technique or polygraph equipment is old and antiquated?

If so, don’t discount the value and reliability of a polygraph yet. There are proponents of other lie detector techniques that claim to have “no equal” and refer to the polygraph as “outdated and un­reliable.” There is some truth to this claim. There are no equals, and the polygraph is the oldest and most reliable lie detection technique in use today. It is also the only proven lie detection technique is use, based on independent scientific reliability and validity studies, coupled with peer acceptance. The polygraph is the only lie detection instrument used by federal government agencies for investigatory purposes and the polygraph is also used by more state and local law enforcement agencies than any other technique available.  There are two types of instruments available in today's market.  Analog and computerized instruments are both being manufactured by at least two of the world's leading and tenured polygraph instrument companies.  The cost of the in­struments are somewhat similar although analog equipment is still somewhat more expensive.  Both instruments are extremely accurate and use the same physiological data for test interpreta­tion.  The analog instrument has an actual chart drive and paper whereon the physiological data is deposited.  Computerized instruments record the data into a computer wherein it is calculated by algorithmic programs.  Examiners using computerized equipment continue to score their charts manually to validate the computer's scoring process.  National and recognized polygraph associations forbid its members from making any disparaging remarks or claims about either type of instrument such as making claims that one is more accurate than another.  Beware of any company that might practice this type of salesmanship because this type of salesmanship is always patently false and is probably being stated for quite obvious and sinister purposes.

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How accurate is a polygraph test result?

The current polygraph research indicates that when a specific single issue polygraph exam, con­ducted by a qualified, trained, and experienced polygraph examiner, is properly administered the accuracy rate is between 95% and 98%. This percentage is still higher than other forms of evi­dence, including psychiatric opinions, suspect identification as provided by victims and wit­nesses, and fingerprint identification. The polygraph is the most accurate tool available today for determining truth or deception. The accuracy of the multi-issue exam drops in accuracy due to a number of psychological factors. These statistics do not include “inconclusive” test results in which no opinion of truth of deception can be made from the physiological data collected on the polygraph charts.

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What kind of questions may be asked on a polygraph examination?

Normally, eight to ten questions are asked on a polygraph test. Prior to administering the test, all test questions are reviewed with the examinee, word for word. The question review process eli­minates any misunderstandings, confusion, or attempts to rationalize the true meaning of any test question. There are no surprise or trick questions. The test series consists of relevant questions interspersed with irrelevant and comparison questions.

1.      The answer to each test questions is limited to either a yes or no. There are no narra­tive answers or interrogation taking place during the polygraph test as por­trayed on television or in the movies.

2.      Compound test questions or test questions that ask for opinions, feelings, emo­tions, intent, or frame of mind must not be used.

3.      Hypothetical questions or questions about future events must not be used.

Do you need more information or would you like to schedule a test?

Please feel free to call Vision Investigative Services.  We will be most happy to assist you in any way possible.  Thank you for taking our tour of frequently asked questions.

If you need immediate assistance call us at: 707.332.7755

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