Cheat a Polygraph Test (Lie Detector)

There are a variety of instances in which you may be subjected to a polygraph, or lie detector examination. These tests can be a source of tremendous anxiety, even for people with nothing to hide, and for good reason. Polygraph examinations are interrogations and it is all too common for innocent people to fail them for no reason, resulting in the denial of employment or false criminal accusations. Fortunately, they are easy to trick, so follow these steps to take control of your interrogation. Remember to tell the truth.


Apply Polygraph Countermeasures

  1. Say only what you need to. “Yes” or “No” answers should be all you need for most of the test. Resist the temptation to explain your answers or to go into details, although the polygrapher may try to get you to do so. Be courteous and cooperative, but do not offer any more information than is absolutely necessary.
  2. Don’t admit anything relevant. No matter what the lines on the chart look like, nothing is more certain or damaging than your confession. The polygrapher will most likely try to convince you that he or she can “see” a lie in your polygraph, even if there’s nothing abnormal there. Don’t fall for it. However, you want to appear honest, so don’t be afraid to make minor admissions to control questions. Just make sure you don’t admit anything in these that can invite further questioning or that may be construed as relevant.
    • Remember that the job of polygraphers is to extract confessions. In many ways, the whole examination is a complex ruse to trick you into confessing something.
  3. Answer questions firmly, seriously, and without hesitation. This is no time to joke around or try to be crafty. You want to appear earnest, cooperative and resolute.
  4. Breathe normally. Except during control questions, you should try to maintain a breathing rate of 15-30 breaths per minute. Do not breathe too deeply.[1]
  5. Alter breathing rate with control questions.[2] The polygrapher will compare your physiological responses to control questions to your responses to relevant questions. If the deviation from normal during control questions exceeds the deviation from normal during relevant questions, you will pass. If you react more to a relevant question than to control questions, the polygrapher will perceive (rightly or wrongly) that you are lying in response to something relevant and you will likely fail the polygraph.
    • Change your breathing pattern when a control question is asked. You can make it faster or slower, hold your breath for a couple seconds after an exhalation, or breathe more shallowly. Do this for 5-15 seconds and return to your normal breathing pattern before the next question.
  6. Answer control questions strangely.[3] When you are asked a question that is obviously a control question, answer in a vague or odd fashion. For instance, if you're asked what year it is, you might respond with, "the year of the snake" or such an answer. Your goal is to make it difficult for the tester to get a bead on what a "normal" response is for you.
  7. Think of something mentally stressful when answering a control question.[4] If you can artificially worry yourself when answering a control question, you can modify the results of your test so that your "normal" responses appear the same as the responses that actually worry you. For instance, you might try doing mental arithmetic when a control question is asked. Count backwards by 7s in your head as quickly as possible or do some quick long division. This will help change your blood pressure and heart rate to a level that's similar to that which occurs during actual stressful situations - like answering a revealing question. Alternatively, you can mentally picture a frightening scenario, like, for instance, drowning, as this typically will also increase your heart rate and breathing.
  8. Handle the post-test interview. After you’re disconnected from the machine, the polygrapher may leave you in the room for a while and come back. The polygrapher may then claim to “know” that you are lying about something. This is a trick. Remain calm and firmly but politely repeat your denial. Don’t change or augment your answers and decline extended post-test interviewing if possible.

Be on Your Guard

  1. Remember that the polygrapher is not your friend. The polygrapher may try to convince you that he or she is on your side and will help you out if you’ll just be truthful. This is deception; don’t buy it.
  2. Beware of pretest tricks. Polygraphers will frequently attempt to instill fear in the subject or convince the subject of the accuracy of the polygraph machine. The theory is that the more you fear that you may be caught, the greater your physiological reactions will be. Don’t believe the hype. The polygrapher may also try to elicit reactions from you based on fear. For example, he or she may say that you need to wash your hands so the machine can accurately read your sweat output. A hidden camera in the bathroom may then catch the subject going into the bathroom as directed, but not washing his or her hands.[5]

Learn How to Recognize Question Types

  1. Identify the types of questions you are being asked. There are three basic types of questions you will be asked: relevant, irrelevant and control. Irrelevant questions are those that are obvious, such as “What is your name?” or “Are the lights on in this room?” Relevant questions are the important ones, such as “Did you leak that memo to the media,” “Have you ever stolen money from an employer?” or “Have you ever sold drugs?” Control questions are those against which your reactions to relevant questions will be compared. These are usually questions to which (just about) everybody can answer “yes,” but which everybody is uncomfortable honestly answering. Examples might include, “Have you ever lied to get out of trouble?” or “Have you ever taken anything of value from an employer?”[6]
  2. Conceal your knowledge of polygraphy. The polygrapher may ask you, before the test if you’ve done any research on polygraph tests or what you know about them. Do not disclose that you’ve done extensive research. Act as though you don’t know much about polygraph examinations, but that you do believe polygraphy to be a science and polygraphs to be reliable (or at least do not exhibit any doubt as to their reliability). The polygrapher may try to trick you by mentioning certain technical terms and acronyms such as, “Your test came back NDI.” While you will know that “NDI” means “no deception indicated,” you need to act as though you have no idea what it means. Too much knowledge of the process may make the polygrapher think you’ve got something to hide, even if you don’t.

Prepare Well in Advance

  1. Learn about polygraphs.[7] If your career or court case depends on it, wouldn’t you do as much research as you can? Read about what they are and how the process generally works.[8] The most important thing to know is that polygraphy is not an exact science. In fact, it is not a science at all. It was created by interrogators, not scientists, and frequently produces incorrect results.
  2. Find out what the tester is looking for. A polygraph examination is administered to help find out specific information, such as whether you’re a spy or whether you’ve used drugs. If your test is prompted by a specific incident, you probably know what the examiner is looking for. For pre-employment screening tests and the like, research the company or agency’s policies to determine what you can and cannot admit.
  3. Practice countermeasures in advance. Practicing these beforehand can greatly increase the likelihood that you will “pass” the polygraph examination, but only if you do them right. Once you read about the measures, be sure to practice them well before the test so that you’re thoroughly prepared.[9]
  4. Approach your whole “polygraph day” as a test. Treat the polygraph examination as an extreme job interview. Dress conservatively and appropriately, and try to make a good impression before the test. Be sure to arrive on time and, unless it's the direst of circumstances, do not reschedule or attempt to postpone the exam.[10]
    • Be aware that your every move is very likely being observed from the moment you arrive at the testing location. There may be hidden cameras in the waiting room and the restrooms, and there is almost certainly a camera or two-way mirror in the polygraph room. Your polygraph examination begins long before you are hooked up to the machine and ends only when you’ve left the testing location.


  • If you are required to take a polygraph as part of your condition of probation or parole, a failed polygraph, or your polygrapher's accusation that you used of countermeasures, can be used in revocation proceedings.
  • There are several subtle variations on the polygraph test. Be sure to research these thoroughly before your test to be prepared for anything they might throw at you.
  • Think of something that calms you down,[11] or something you know that you never did during an accusing question. See it in your mind while answering the question.
  • The easiest way to avoid failing a polygraph is to refuse one. For pre-employment screenings, this will almost certainly insure that you don’t get hired. However, it’s still a viable option, especially if you are opposed to the usage of polygraphs in general.
    • While refusal may prevent you from getting hired, it probably will not get you fired. In the U.S., private sector employers may not terminate employment or take other such adverse actions based solely on a polygraph refusal. However, this protection usually does not cover government employees. If your polygraph is part of a criminal investigation, you have a right (at least in the U.S.) to refuse. Refusal to submit to a polygraph is generally not admissible in criminal court, and polygraph results themselves are rarely admissible. In some states polygraph results are admissible in civil and administrative proceedings.


  • Perform only one heart rate/blood pressure altering countermeasure at a time or it may become too obvious.
  • Be aware that you might not be able to beat the lie detector even using these methods.
  • If you are accused of deception or using countermeasures, you will likely be eliminated from the job pool. If you are on parole/probation and are mandated to take a polygraph, a polygrapher's accusation that you used countermeasures may land you back in jail.
  • Biting your tongue is highly effective,[12] but may be detectable if you move your mouth observably. Some polygraphers make examinees wear a special set of headphones designed to measure jaw movements.

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