Frequently Asked Questions

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What is a polygraph?

How accurate is a polygraph examination?

How does a polygraph work?

Will I feel pain during the polygraph examination?

Of what does a polygraph examination consist?

Can I be forced to take a polygraph examination?

I am telling the truth, but I am nervous about taking a polygraph examination. How does the examiner establish the difference between the state of nervousness and the reactions manifested following a lie?

I suffer from hypertension. Can this condition affect the result of the polygraph examination?

Can drugs or medications affect the result of a polygraph examination?

Can I know beforehand what questions I will be asked during the polygraph examination?

How long does a polygraph examination last?

Will I be informed of the result of my polygraph examination?

Is a polygraph examination and its result admissible as evidence in Canada's justice system?

Are there persons who should not submit to a polygraph examination?

How are polygraph examinations being used today?

Q:  What is a polygraph?

The term "polygraph" derives from the Greek words poly (many) and graph (writing) — "many writings". The name refers to the manner in which selected physiological activities are simultaneously collected, measured and recorded.

The polygraph is a scientific diagnostic instrument that is used by a polygraph examiner to administer a polygraph examination for the purpose of verifying the truthfulness of a person's statement with regard to a specific issue - whether criminal, civil or private - that is the object of an investigation.

The polygraph is often called the "lie detector".

An examiner may use an analog polygraph, however, today, most polygraph examinations are administered using digital or computerized polygraph technology.

Q:  How accurate is a polygraph examination?

Research conducted by the scientific community, government agencies and independent universities clearly indicates that a polygraph examination — when properly administered by a professionally-trained and competent polygraph examiner, using federal standards of procedure and instrumentation — has a high level of accuracy in detecting truthfulness or deception.

According to the American Polygraph Association, over 250 studies have been conducted over the past 75 years on the accuracy of polygraph testing. These studies estimate the accuracy of the results to be in the range of 90-95 per cent.

Like any other instrument that is used as an assessment tool to measure human physiology for the purpose of forming professional opinions, the polygraph is not infallible. However, the scientific community agrees that polygraph examinations, as they are being used today, have great probative value in detecting truthful persons and deceptive ones, and there is still no other alternative testing technique available for truth verification and lie detection that performs better.

Q:  How does a polygraph work?

Prior to a polygraph examination getting underway, the examiner will fasten various painless components to and around the examinee's body, thereby connecting him or her to the polygraph instrument. These components are equipped with sensors that serve to collect, measure and record, onto polygraph charts, the examinee's physiological data obtained from three major systems of the body — i.e., i) the cardiovascular system (heart rate, blood pressure, blood volume); ii) the respiratory system (breathing patterns); and iii) the electrodermal system (sweat gland activity) — as he or she answers a series of questions pertaining to a specific issue during the course of the polygraph examination.

Q:  Will I feel pain during the polygraph examination?

No. Some people are concerned that they might receive an electrical shock as a result of being connected to the polygraph instrument. Be assured, however, that there is no possibility of this. The only sensation that some people may feel is a slight pressure on the arm because of the blood pressure cuff that is applied there. This is the same cuff that is used by doctors and nurses to measure your blood pressure.

Q:  Of what does a polygraph examination consist?

A polygraph examination consists of three separate and distinct phases.

These are: 1. Pre-test Phase; 2. In-test Phase; 3. Post-test Phase.

1. Pre-test Phase

During this first phase, the examiner will:

• inform the examinee of the specific issue that is under investigation;
• advise the examinee of his or her constitutional rights and of the voluntary action of submitting to a polygraph examination;
• complete the necessary documentation;
• provide the examinee with a detailed explanation of the polygraph procedure and the polygraph instrument with its components and how these work;
• answer any questions that the examinee may have;
• obtain the examinee's version of the facts regarding the specific issue in question;
• formulate and review with the examinee all the questions that will be asked of him or her during the polygraph examination.

2. In-test Phase (or Chart-collection Phase)

The polygraph examination takes place during this second phase.

Once the examination is underway, the examiner will administer a minimum number of three separate tests each lasting approximately 5 minutes — and a maximum number of six tests — during which the examinee's physiological data will be continuously collected, measured and recorded, onto polygraph charts, as he or she answers the set of questions that were formulated and reviewed during the pre-test phase.

3. Post-test Phase

During this final phase, the examiner will analyze, interpret and evaluate the examinee's physiological data collected during the polygraph examination, afterwhich the examiner will form one of the following professional opinions:

NDI — No Deception Indicated The examinee is telling the truth.

DI — Deception Indicated The examinee is not telling the truth.

INC — Inconclusive  The evaluation of the physiological data is inconclusive.

The examiner will then give the examinee the result of the polygraph examination. If the physiological data recorded on the charts shows reactions on the part of the examinee to the relevant questions that were asked, he or she will be given the opportunity to explain these reactions.

Q:  Can I be forced to take a polygraph examination?

No. In order for a polygraph examination to be administered properly, the examiner will ask you to sit still and not to move any part of your body needlessly while the examination is in progress. Since the examiner requires your full cooperation in this regard, you must accept to undergo a polygraph examination.

If you do not want to take a polygraph examination, you can exercise your right of refusal.

Q:  I am telling the truth, but I am nervous about taking a polygraph examination. How does the examiner establish the difference between the state of nervousness and the reactions manifested following a lie?

It is quite normal for an innocent person to be nervous about taking a polygraph examination and the experienced examiner is aware of this fact. Nervous reactions that are recorded onto the polygraph charts are not interpreted by the examiner as a manifestation of deception because such reactions are completely different from those that are 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, the examiner will do his or her best to reduce your degree of nervousness prior to the examination getting underway.

Q: I suffer from hypertension. Can this condition affect the result of the polygraph examination?

While the polygraph does measure and record blood pressure, hypertension does not cause physiological reactions that are characteristic of those obtained when a person is lying. More precisely, a lie represents a different curve on the polygraph charts from one that is produced as a result of hypertension. 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 currently undergoing treatment for hypertension, psychological problems or any other medical condition.

Q:  Can drugs or medications affect the result of a polygraph examination?

Anti-depressants — such as Lithium, Prozac, Valium, Xanax and Beta-blockers — can affect the result of a polygraph examination in that an inconclusive result can be obtained. For some people, however, these drugs will have no effect on the result of the examination.

Contrary to some claims, drugs and medications do not allow a person to "beat" a polygraph examination. During the pre-test phase, it is immediately apparent to the well-trained and competent examiner whether the examinee is fit to undergo an examination.

Q: Can I know beforehand what questions I will be asked during the polygraph examination?

Yes. During the pre-test phase, the examiner will formulate and review with you all the questions that you will be asked during the polygraph examination. If there are certain questions that you do not want to be asked, you must specify these to the examiner during the reviewing stage and he or she will not ask you these particular questions.

The polygraph examination will have no surprise or trick questions.

Q:  How long does a polygraph examination last?

A polygraph examination lasts about two hours. Some can last more or less time depending on the issue that is being investigated.

Examinations are audio and video recorded.

Q:  Will I be informed of the result of my polygraph examination?

Yes. The American Polygraph Association Standards and Ethics Committee requires that each person who submits to a polygraph examination be informed of the result immediately after the polygraph charts have been evaluated and a professional opinion has been formed by the examiner.

Q:  Is a polygraph examination and its result admissible as evidence in Canada's justice system?

The polygraph examination and its result are not admissible in Canada's criminal justice system. This statement of law was made by Justice McIntyre in R. v. Béland and Phillips [1987] 2 S.C.R. 398 Docket: 18856.

The criminal courts of Canada hold that the result of a polygraph examination is an opinion put forth by the polygraph examiner and that evidence of this type should not supersede the role of the judge and jury to decide the credibility of a witness. Trial by judge and jury has long been the cornerstone for Canada's criminal justice system. However, the testimony of the polygraph examiner can be heard on a voir dire when a confession has been obtained.

The result of a polygraph examination can be admissible in civil court or in labour court. The law, however, as it pertains to the admissibility of such evidence, is unclear and civil courts across Canada have adopted a variety of views, ranging from acceptance of polygraph evidence, to partial acceptance, to non-acceptance. Some judges have taken the view that the decision of Justice McIntyre in R. v. Béland and Phillips applies to civil as well as to criminal matters, while others have taken the stance that any evidence of witness credibility — if probative and relevant — should be admitted, including polygraph evidence.

Q:  Are there persons who should not submit to a polygraph examination?

The following persons should not submit to a polygraph examination:

• A person who is being forced to do so;
• A person who suffers from a serious heart condition, unless he or she has obtained prior written permission from a physician to do so;
• A pregnant woman, unless she has obtained prior written permission from a physician to do so;
• A person judged to be mentally incompetent;
• A person who suffers from a severe nervous condition;
• A person who suffers from a severe respiratory illness;
• A quadriplegic;
• A person who has a bad cold;
• A person who is in extreme pain at the time of the polygraph examination;
  Examples: migrain, toothache, recent injury, etc.
• A person who feels extremely fatigued.

Q:  How are polygraph examinations being used today?

Polygraph examinations are being used around the world by government, law enforcement and security agencies, the legal community, the private sector and private citizens for the purpose of verifying the truthfulness of statements by persons with regard to specific issues — whether criminal, civil or private — that are the object of an investigation.

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