Everything You Wanted To Know About Polygraphs


  1. How accurate is the polygraph? (back to top)

    U.S. Government studies have concluded that the single-issue (one question) polygraph exam, conducted properly by a qualified examiner, is 87 to 95 percent accurate.  It is the most accurate tool available today for determining truth or deception.  Accuracy of the multi-question exam drops to around 80 percent due to a number of psychological factors.  These statistics do not include "inconclusive" results in which no opinion can be made from the polygraph charts, which happens about 20% of the time.
  2. How does the test process work? (back to top)

    a: The examiner receives and reviews the facts surrounding the case.

    b: The examiner explains the test process to the subject and reviews the case facts during the pretest interview.

    c: The examiner designs the specific test questions and reads each question to the subject to make sure each one is easily understood.

    d: The test subject is attached to the polygraph instrument and given additional instructions.

    e: The questions are read to the subject several times while he/she is attached to the polygraph sensors.

    f: After all charts (polygrams) have been run, the examiner analyzes the charts and develops a numerical score for the test. This score results in a conclusion of either truthful, deceptive or inconclusive.

    g: The examiner will transmit the test results to the client verbally, usually within 24 hours. A written report may be requested, however some examiners will charge a small fee for this report.

    NOTE: Polygraph exams are conducted in private with no other persons permitted in the examination room during the test (other than possibly an interpreter).
    NOTE: The average polygraph exam takes from one to three hours to complete.

  3. What does the polygraph record? (back to top)

    A standard polygraph records changes in blood pressure, pulse rate, pulse strength, galvanic skin reflex (sweat gland activity), and upper and lower breathing patterns. It does not matter if the subject is "nervous" during the testing process - that is to be expected. The polygraph records significant changes from the subject's "norm" when specific questions are asked. A person intending deception to a particular question will activate his/her Sympathetic Nervous System as a "self defense" mechanism when that question is asked on the test. The SNS activation will cause recognizable changes in one or more of the physical responses.
  4. Is the computerized polygraph better than the mechanical polygraph? (back to top)

    Mechanical (or analog) polygraph equipment has been around for 50 years and is still widely used today. Just a few years ago computerized polygraphs were developed. These new systems included complicated chart analysis formulas and inkless display systems (on a computer screen rather than a roll of chart paper). Scoring of the charts is done the same for both systems, but the computerized system has built-in aids for the examiner and prevents equipment failures that are sometimes experienced with mechanical equipment. In our opinion, at this time the computerized systems are not well-enough advanced to be called superior to the analog systems, although they are admittedly easier to use. A competent and qualified examiner can be equally effective with either system.
  5. What kind of questions can I ask someone? (back to top)

    Test questions are limited to "yes" or "no" answers. Test questions must have definitive objective answers and may not be opinions. Test questions must relate to past events of a factual nature. Wording of questions must only have one interpretation. Some examples of "good" and "bad" questions:

    Not acceptable - "On March 3, 2000, were you thinking of stealing that television set from 456 Main Street in Anytown?"
    Acceptable - "On March 3, 2000, did you steal that television set from 456 Main Street in Anytown?"

    Not acceptable - "Did you ever cheat on your wife?"
    Acceptable - "Since you married Susan, have you had sexual intercourse with anyone other than Susan?"

    Not acceptable - "Do you love someone other than Susan?"
    Acceptable - "Since you married Susan, have you told someone other than Susan that you loved them?"

    Not acceptable - "Have you ever lied to your wife about dating someone?"
    Acceptable - "Since you married Susan, have you dated anyone other than Susan?"

    Questions in the same exam must be related to one another. For example, we can ask about extramarital sex and extramarital dating in the same test, but we can not ask about extramarital sex and use of drugs in the same test. If distinctly separate issue types must be covered, they must be asked in separate examinations.
  6. How many questions can I ask? (back to top)

    The most accurate test which can be conducted is the one-question (single issue) test, but most clients are not satisfied with having only one issue resolved.  Slightly less accurate is the multi-issue test in which the examiner can cover three (3) relevant questions during a single examination, as long as these questions are related to one another (see #4 above). These three questions will take one to three hours to cover effectively due to the extensive test process required. If more questions must be asked, another exam must be designed and conducted following the first one. This usually adds to the time and cost involved. Additionally, an effect called "anti-climax dampening" makes test results less reliable with an increase in the number of relevant test questions. It is the client's choice whether to have a single-question test or a multi-issue test, considering the difference in accuracy (see #1 above). Finally, a healthy individual can only produce readable polygraph charts for a limited period of time. After this time has expired, it is impossible to generate a conclusive polygraph test and any further testing must be scheduled for a different day.
  7. I heard that sex crimes require an examiner with special training. (back to top)

    Most competent examiners can handle routine sex crimes, but there is a new certification for examiners called "Certified Post -Conviction Sex Offender Examiner" which requires 40 hours of additional specialized training. If your exam involves an allegation of a sex crime it may be wise to seek out an examiner with this additional certification.
  8. Can someone beat the test? (back to top)

    The polygraph works by recording changes in a person's Sympathetic Nervous System, part of the Autonomic Nervous System, which operates independently of conscious thought. For example, your lungs and heart continue to operate even when you are asleep - you don't have to think about it. These systems can be consciously controlled only very slightly, and attempts to change these systems are usually picked up by the examiners, who are trained to identify such things. It is highly unlikely that someone can alter the outcome of a polygraph exam, but it is not impossible. A verified accuracy rate as high as 95% attests to this fact.

    Use of certain drugs and medications can also affect the exam, but such use generally results in an "inconclusive" test. It is virtually impossible to change a result from "deceptive" to "truthful" through the use of drugs or medications prior to an exam. If drugs are suspected, a pre-test (or post-test) drug screening is advised.
  9. Is the polygraph admissible in court? (back to top)

    Federal courts have ruled that polygraph is NOT per-se inadmissible in a court procedure, but that it may be considered when standard rules of scientific evidence have been met. In other words, applicants must apply to the judge for admissibility under the "Daubert" standard of evidence on a case-by-case basis. Individual judges can still decline to accept polygraph results, however. Each jurisdiction must be checked to determine admissibility standards. One of the greatest fears keeping polygraph evidence out of courts is the fact that such evidence would carry greater weight than other equally-important evidence and would tend to sway a jury in one direction even though other evidence may point the other way. In most cases, polygraph evidence is used during pre-trial negotiations and plea bargain agreements rather than during the trial itself.
  10. Can an employer have an employee take the test? (back to top)

    Yes, but only under certain conditions. The Employee Polygraph Protection Act of 1988 requires that the employer have suffered a specific economic loss, that the employee to be tested had access to the missing property or loss, and that the employee is suspected of involvement in the missing property or loss beyond mere access. If these conditions are satisfied, the employer must make a request in writing that the employee take the exam. We can provide a form for such requests. CLICK HERE to get the form. This request must advise the employee that the exam is voluntary and that no action can be taken against him/her solely for refusing to take it. The employee must also be advised of the incident under investigation, his/her legal rights, and a number of other notifications required under the law. This request must be presented to the employee at least 2 business days prior to the scheduled exam.

    Questions must be limited to the specific loss only. The examiner is not permitted to ask questions about losses other than those listed in the notification form.

    If an employee "fails" a polygraph under these conditions, the employer still may not take action against the employee without additional supporting evidence indicating the employee's involvement in the loss.
  11. What should I look for when hiring a polygraph examiner? (back to top)

    First thing, if the state you are in requires licensing, make sure the examiner has a current license. Less than half of the states in the U.S. have this requirement. Next, make sure the examiner has been "certified." Every examiner must attend a polygraph training program which lasts 7 to 8 weeks (or longer if trained with the government). After graduation, the examiner must conduct a certain number of exams during an "internship"
    period. After the internship (usually one year) the school reviews the examiner's work and grants the certification if this work was done to standards. After certification, most examiners must complete a certain amount of continuing education or advanced training programs. Beware of an examiner who's been operating for 25 years but has not taken advanced training in many years. Technology changes and examiners must keep current with these changes. Look for professional affiliations and membership, such as the American Polygraph Association or other similar groups which set professional standards for examiners. Finally, make sure the examiner has experience with the type of exam you need done. An examiner with 10 years experience testing rapists and murderers may not be the right person to see if your 15 year old daughter stole money from someones locker.
  12. Is there a best time of day to give a polygraph? (back to top)

    Yes. Since it is important that the person tested be capable of maximum reactions (for scoring purposes), that person should be well rested prior to the exam. In other words, testing done in the morning will be more productive than those done later in the day, and testing done in the evening significantly increases the risks of an inconclusive result. The person should also not be tested right after an argument, interrogation or long day of work if possible.
  13. What if I can't get to the examiner's office? (back to top)

    Most examiners will travel to your location for an additional fee. Be sure to have adequate facilities available. This includes a quiet private room for testing with a table and two chairs (one chair with fixed back and no wheels).
  14. Is my deposit refundable? (back to top)

    If the examiner does not provide your polygraph due to his/her choice or schedule problem, the deposit is refundable. If the client cancels the exam for any reason, the deposit is forfeit and another deposit must be applied prior to rescheduling.
  15. Will I incur any additional fees? (back to top)

    Not usually. The fee listed is for a "basic" polygraph with three or less primary (relevant) questions conducted during normal business hours at the examiner's location of choice. Additional charges may be incurred for (1) exams covering more than three questions (2) use of an interpreter (3) use of audio or video recording equipment (4) typewritten reports (5) exams conducted after business hours or on weekends (6) examiner's testimony in court or other proceeding.
  16. Why do prices vary so much depending on where you take the test? (back to top)

    Like anything else, the price of a polygraph test is "market" driven. In some areas the exam may be as low as $300 while in others it is $700. The fee is usually determined by supply and demand.
  17. Can someone under age 18 take a polygraph? (back to top)

    Yes, but the examiner must first have written consent of a parent or guardian. However, most examiners will not test anyone under 12 years of age barring extraordinary circumstances.
  18. Can medications affect the test results ? (back to top)

    Yes. Any drug or medication that suppresses normal activity of the Central Nervous System (sedatives, anti-anxiety meds, blood pressure stabilizers, etc.) will reduce the strength of reactions found on the polygraph charts, resulting in a higher likelihood of inconclusive results. The medications will not change the outcome of an exam and only serve to reduce the odds of resolving the problem. It would be our suggestion to test any person who is using these types of drugs or medications on a computerized polygraph which is capable of greater sensitivity than the analog version.
  19. What if the person has a medical condition? (back to top)

    A polygraph exam does not cause any direct injury to the person being tested. The only discomfort is a standard blood pressure cuff which goes on the arm (typically) and is inflated for less than five minutes at a time. There are increased stress levels during the testing process which should be considered. Some medical conditions are sensitive to increased stress levels, such as some heart conditions. Depending on the medical condition, most examiners would require an approval from the treating physician prior to conducting an exam on someone with such a condition.


  20. Can a pregnant woman be tested? (back to top)

    It does not affect the outcome of a polygraph exam to test a pregnant woman unless the fetus is making excessive movements or causing pain to the mother during the exam. Many examiners will not test a pregnant woman under any circumstances, but others are ok with testing after the first tri-mester. Some examiners will test only with a note from the woman's physician stating that there are no complications from the pregnancy and that the stress of taking a polygraph would not impact the health of the mother or fetus.


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  21. What does it mean when someone "fails" a polygraph?(back to top)

    When a polygraph examiner concludes that deception is indicated to one or more of the subject's answers, the subject is said to have "failed" the exam.  Deception is indicated when the person's autonomic nervous system displays a significant and repetetive "defensive" reaction to the relevant test question.  Although this reaction in itself is not a "lie," years of research have found that 90-95% of persons who display this reaction were either lying to the relevant questions or were withholding pertinent information relating to these question.  Frequently, an examiner will conclude only that "the subject can not be excluded as a suspect" when deceptive reactions are present.  It is important to note that some persons will "fail" a polygraph even though they are telling the literal truth but continue to hold back pertinent or incriminating information from the examiner.   We strongly suggest that no one make a life-altering decision based solely on the results of a "failed" polygraph test without the existence of additional evidence supporting this test result.
     
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