The British Polygraph Society

Frequently Asked Questions

Q: What is a Lie Detector Test or Polygraph?

Derived from the Greek language, the word “polygraph” means “many writings”. It refers to the manner in which selected physiological activities are continuously and simultaneously recorded. ​The polygraph instrument is often referred to as a “lie detector”.

A polygraph is a diagnostic instrument used by a formally trained polygraph examiner for the purpose of collecting, measuring, and recording selected physiological data obtained from an examinee as he or she answers a series of questions relating to a specific issue — whether criminal, civil, or private — during a polygraph examination. This data will then be analyzed and evaluated for psychophysiological credibility assessment.

​Lie Detector Tests or Polygraph examinations are used in more than 50 countries by government organizations worldwide, law enforcement agencies, private security firms, the legal community, the corporate sector, and private citizens.

​The development of medical-grade instrumentation and software has allowed for computerized polygraphs to record physiological responses directly to a software program and display this data on a computer monitor.

During a polygraph examination, the polygraph instrument detects, measures, and records physiological data obtained from three major systems in the human body, all of which are controlled by the Autonomic Nervous System:

1) Respiratory System: Respiratory activity patterns and changes;

2) Cardiovascular System: Heart rate, relative blood pressure, blood volume;

3) Electrodermal System: Galvanic skin response, i.e. sweat gland activity.


Q: How accurate is the Lie Detector Test?

The Lie Detector Test or Polygraph examinations have gained general acceptance in the scientific fields of psychology and psychophysiology in those areas devoted to credibility assessment. Research conducted by the relevant scientific community, government organizations, and independent universities clearly indicate that a polygraph examination — when properly administered by a formally trained and competent polygraph examiner — has a very high level of accuracy (on average 94 to 98% – click here to see the research) in verifying the truth and detecting deception.

According to Dr David C. Raskin, the world-renowned expert and leading scientist in the field of polygraphy, the scientific data concerning the validity of the polygraph can be summarized as follows:

“High quality scientific research from the laboratory and the field converge on the conclusion that a properly conducted CQT (Comparison Question Test) is a highly accurate discriminator of truth tellers and deceivers. The research results converge on an accuracy estimate that exceeds 90 percent.”

According to the American Polygraph Association (APA), 80 research projects, which included both laboratory and field studies, have been conducted and published since 1980 on the validity and reliability of polygraph testing. These projects involved approximately 6,300 polygraph examinations. Of the 23 field studies conducted, the accuracy of polygraph testing was estimated to be 95 percent.

Like any other diagnostic instrument that is used to measure human physiology for the purpose of evaluation and forming professional opinions thereupon, the polygraph instrument is not infallible. The relevant scientific community agrees, however, that polygraph examinations have a very high probative value in distinguishing truthful individuals from deceptive ones, and that no other alternative testing technique for truth verification and lie detection performs better.

Q: What kind of questions can be asked?

The polygraph test questions will vary according to the case issue but all questions are specific and pertinent to the issue to be resolved. Questions only require a “yes” or “no” answer and with no explanation or qualification.

Q: Will I know what questions I’ll be asked during the Test?

Yes. During the pre-test interview on the day of the test, the examiner will formulate and review with you (the examinee) all the questions that will be asked during the polygraph examination. There will be no surprise or trick questions.​

Q: Can I be forced to take a Lie Detector Test?

No. No one can be forced to undergo a polygraph test. The test is totally voluntary. To properly administer a polygraph examination, the examiner will need your volunteer assistance by signing a consent form prior to the test. There are few basic instructions which the examinee should follow during the In-test Phase (Chart Collection) as to sit still and not to move needlessly while the examination is in progress. The examiner will also ask you (the examinee) to breathe normally, not to take deep or short breaths, not to hold your breath or to modify it, as all such maneuvers will be detected by the anti-countermeasure sensor and could lead to a termination of the test due to a countermeasure/cheating attempt detection.
Since the examiner requires your full cooperation in this regard, you must voluntarily accept to undergo a polygraph examination.

If you do not want to submit to a lie detector test /polygraph examination/, you can exercise your right of refusal at any time before or during the test.

Q: How long does a Lie Detector Test last?

A Professional Lie Detector Test or Polygraph examination lasts about 2 hours. Some can last more or less time depending on the complexity of the issue under investigation. All polygraph examinations are audio and video recorded for quality and security purposes. All collected data during the polygraph examination will be deleted once the professional verified report will be issued and sent to the client within 24 hours after the examination completion.

Q: Can I be in the room during someone else’s test?

No. In order to preserve a sterile environment, no one other than the examiner and examinee can be in the examination room during the procedure. Polygraph is a diagnostic procedure which can be adversely affected by distractions.

Q: Who uses Lie Detector Tests or Polygraph examinations today?

Lie Detector Tests or Polygraph examinations are used in more than 50 countries by government organizations worldwide, law enforcement agencies, private security firms, the legal community, the corporate sector, and private citizens.

Q: Can drugs, medications or high blood pressure (hypertension) affect the result?

Contrary to some claims, drugs and prescription medications do not allow a person to “cheat” or “beat” a lie detector test or polygraph examination.

The examinee’s medical and drug history should be filled by the client in the pre-examination assessment form which we’ll send on the email provided during the booking process.
NOTE: Medical and drug-related questions also will take place during the pre-test interview with our accredited examiner to establish the examinee’s physical, psychological, and physiological history and to determine whether he or she is fit to undergo a lie detector test. Here, the examiner will ask the examinee specific questions about any prescribed medications or drugs he or she may be taking.

Hypertension does not cause physiological reactions that are characteristic of those obtained when a person is deceptive. A truthful answer is evident to the examiner even if the examinee suffers from high blood pressure.
Be sure to inform the examiner if you are being treated by a medical professional for hypertension or any other medical condition.

Q: Can I “cheat” or “beat” the Lie Detector Test?

No, you cannot. If you know you are being deceptive, the polygraph will detect that deception. Any APA qualified polygraph examiner will certainly detect deception. Furthermore, the computerized Lafayette polygraph instruments used by our firm have a phenomenal accuracy rate between 94-98 percent and are used in with highly effective anti-countermeasure sensor allowing our accredited polygraph examiners to detect any countermeasures an examinee may resort to in an attempt to influence the outcome of the polygraph examination.

Q: Will I feel pain during the test?

No. Some people are concerned that they might get an electrical shock as a result of being connected to the polygraph instrument. Be assured there is no possibility of this. The only sensation that people will feel is a slight pressure on the upper left arm where the standard blood pressure cuff is applied and inflated for about 3 to 5 minutes during which time the test questions are asked. The blood pressure cuff is the same as that used by doctors and nurses to measure your blood pressure.

Q: Can nervousness or anxiety affect the test?

It is absolutely normal for anyone to be nervous about taking a lie detector test or polygraph examination and our competent examiners are aware of this fact. Nervous reactions recorded on the polygraph charts are not interpreted by the examiner as a manifestation of deception because the tracings of these reactions are very different from the psychophysiological patterns recorded when a person is deliberately lying.

Once the examination is in progress, the examiner wants you to be as comfortable as possible. To this end, he or she will do their best to reduce your degree of nervousness or anxiety before the examination gets underway as well as will conduct a calibration test to find and fix the examinee’s physiological baseline at the time of the test.