How to Pass a Polygraph Test
If you need to manipulate a polygraph test, stress yourself out when answering control questions to give yourself a higher baseline. You can do this by thinking about something scary or exciting or trying to solve a hard problem in your head while responding to the questions. Additionally, you'll want to stay as calm as possible when answering relevant questions by daydreaming or breathing in an even, controlled way. Finally, avoid using techniques that are easily caught, like tensing muscles, biting your tongue, or pinching yourself.
Understand how a polygraph works. A polygraph cannot detect a lie, per se, but it does track physiological changes in your body, like your blood pressure, pulse, respiration, and perspiration, thereby detecting physiological conditions that occur when you lie. Once you arrive for the appointment, the equipment and process will be reviewed. It does not hurt to familiarize yourself with the basics on your own, but avoid polygraph horror stories posted on the Internet, since these will only make you more nervous than you need to be. Try not to overthink the test beforehand. If you spend too much time worrying about the polygraph test before you take it, you run the risk of skewing the test against your favor by finding things to condemn yourself on needlessly. To avoid worrying yourself unnecessarily, do not ask anyone who has taken a polygraph what it was like, do not spend time soul-searching before the test, and do not try to anticipate which questions will be asked. Try to avoid spending too much time reviewing anti-polygraph websites, since these websites often mix fact with hyped-up conspiracies and may cause undue panic. Take care of your body the night and day before. You need to be comfortable during the polygraph in order to provide accurate physiological responses. In order to be comfortable, you need to make sure that you are well-rested and feeling as physically cozy as possible. Follow your usual routine as accurately as possible. Even if your routine includes activities that affect your heart rate, like drinking caffeinated coffee or going for a morning run, you should follow your routine since your body has trained itself to run on those physiological conditions. Try to get seven or eight hours of sleep the night before the test. Make sure that you are not hungry and that you have loose, comfortable clothes on. Complete any forms given to you. Depending on the reason for the polygraph, you might have security clearance forms to fill out or forms requiring your authorization. Take your time on these forms. Read through them carefully and sign your name only when ready. Tell the examiner about any conditions or medications you take. If you are currently ill, the examiner may want you to reschedule the test. Certain drugs, like blood pressure medication, can also affect the results, so you should let the examiner know about those, as well. Illness can make you feel uncomfortable, thereby skewing the results. If you take prescription medications, you should continue taking them as prescribed by your doctor before the test. Contrary to popular belief, most anti-depressant medications cannot alter a polygraph and allow you to "beat" it. You should still tell your examiner about these medications, if applicable, since they can produce abnormal results. Review the questions and take your time understanding them. The polygraph examiner is required to tell you the questions ahead of time. Take all the time you need reviewing them, and feel free to ask the examiner for clarification about uncertain or confusing questions. You must ask for clarification about questions before the test. In most cases, you will not be permitted to do so during the test. In fact, your answers will be limited to “yes” and “no” during the polygraph exam itself, so any discussion you need to have about the test questions must take place before the test itself. Find out which test form will be used. The standard polygraph test is the CQT, or "Control Question Test." In some instances, however, you may be given a "Directed Lie Test" (DLT) or "Guilty Knowledge Test" (GKT) instead. With a CQT polygraph, control questions will be mixed in among the relevant questions. A control question is one that nearly everyone will need to reply "yes" to, even though many people will be tempted to reply "no." Such questions include ones like, "Have you ever told a lie to your parents?" or "Have you ever stolen or borrowed something without permission?" With a DLT, you will be asked several questions by the examiner and directly asked to lie about those questions. In doing so, the examiner can gauge your physiological responses to lying by reviewing the questions he or she knew you lied on. For a GKT, you will be asked multiple choice questions about various facts that only you and the examiner would know. Many of these questions will be about the case. Your verbal responses will be compared to your physiological responses. Let yourself be nervous. Nowadays, no one is expected to remain perfectly calm during a polygraph test, even if the person in question is perfectly innocent and has nothing to hide. By allowing yourself to be nervous, you can provide the polygraph examiner with an accurate representation of your physiological statistics when you are being truthful and when you are lying. The lines on the polygraph screen will never be flat and smooth, even if you are telling the truth. Oddly enough, only the person who is nervous about every answer will appear the most truthful on a polygraph test. Speak truthfully. If you have nothing to hide or be ashamed of, then tell the truth to each question you are asked. This includes control questions, for which many people are expected to lie. The more often you tell the truth, the more accurate the results will be. This is a good thing, as long as you are innocent. While people often believe that there will be "trick" questions designed to trap them into a guilty answer, the current state of ethics surrounding the administration of polygraph exams demands that the questions remain straightforward. No surprise questions will be asked, either. Listen to the entire question thoroughly and answer it precisely. Do not listen to only half the question or answer the question according to what you think it asked rather than what it actually asked. Take your time. You can ask the examiner to repeat a question two to six times, depending on who is examining you. Make sure that you find out how often you can ask for a question to be repeated before the test begins. Do not rush through the questions, since this sense of haste can skew the results against you. Questioning usually takes five to ten minutes, but it may take longer depending on how often you ask to have the questions repeated, how long you take to answer the questions, and the nature or reasoning behind the test. Stress yourself out when answering control questions. If you feel the need to cheat or manipulate the test, one thing that most people recommend is to cause yourself mental or physical stress when you are expected to give the answer to a control question. This will give you a higher baseline, so when you tell lies relevant to the case or situation, any spikes in your responses might be smaller than the spike you just created during the control. Think of a frightening or exciting thought when you recognize an obvious control question. You can also make your heart rate and perspiration increase by trying to solve a somewhat difficult math problem in your head. Try dividing 563 by 42, or some other similar problem. Calm down when answering relevant questions. When asked a question relevant to the case or situation, put yourself in a calm state of mind when you answer. By staying as calm as possible, you can prevent many major spikes in your physiological responses. Essentially, a “lie” only counts if that lie generates a greater physiological response than that which you had while you were telling “white lies” with the control questions. As long as your physiological response to a question and answer produces a less noticeable reaction than any reaction you displayed while answering the control questions, it will probably not count against you. Maintain your breathing pattern and keep in mind that the polygraph is not infallible, and that you are in control of your own physiological response. Daydream about something soothing, like cuddling under a warm blanket with a cup of hot chocolate on a cool night, or taking a relaxing shower or bath. Avoid tricks that are easy to catch. If the examiner catches you trying to cheat the test, you might be asked to schedule another test or the examiner may take countermeasures against further acts of manipulation. Moreover, attempts to manipulate the test might cause the examiner or reviewer to judge your results more harshly once you finish. For instance, do not stick a thumbtack in your shoe and attempt to press down on it to spike your vitals during control questions. Oftentimes, an examiner will have you remove your shoes during the test to avoid such tricks. In fact, while physical pain will cause your vitals to spike, it is usually easier to catch than psychological stress. Biting your tongue, clenching a muscle, or other similar tactics can be caught easily if you are working with a trained polygraph professional. Talk with the reviewer after the test. After you take the polygraph test, a reviewer will go over your results and determine if you need to be questioned further or if any points need to be clarified. The reviewer will likely ask you about your responses only if the results are inconclusive or if he or she suspects you of lying. In reviewing your results, the reviewer and examiner will also consider your emotional state, medical and physical condition, and the factual details of the case or circumstances calling for the test. Wait for your official results and any further instructions. Your results will need to be professionally and officially analyzed before any judgment can be made on them. If you are suspected of lying or if your results were inconclusive, you might be called and asked to take another polygraph test. The American Polygraph Association Standards and Ethics Committee requires the examiner to release the official results to the examinee upon request, so even if the results are not automatically given to you within a week or two, you can call or contact your examiner to request those results. 
Understand how a polygraph works. Try not to overthink the test beforehand. Take care of your body the night and day before. Complete any forms given to you. Tell the examiner about any conditions or medications you take. Review the questions and take your time understanding them. Find out which test form will be used. Let yourself be nervous. Speak truthfully. Take your time. Stress yourself out when answering control questions. Calm down when answering relevant questions. Avoid tricks that are easy to catch. Talk with the reviewer after the test. Wait for your official results and any further instructions. 