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A polygraph examination (credibility assessment, sometimes called a lie detector) is a scientific test that collects physiological data from a person with the purpose of identifying reactions associated with dishonesty.

The polygraph is a medical instrument that records the
physiological changes of the examine. It monitors respiratory
activity, electro-dermal activity and cardio activity. When an individual lies the body goes into a fight or flight syndrome causing physiological changes.These changes are recorded by the polygraph instrument, It is important to note that a polygraph does not include the analysis of physiology associated with the voice. Instruments that claim to record voice or psychological stress are not polygraphs and have not been shown to have scientific support.

Many studies have been done over the years that have documented the accuracy of polygraph to determine truth vs.deception. Generally, the studies found the polygraph's accuracy to be in the high 90% range.

The U.S. Government studies have concluded that when a qualified examiner conducts the test properly, the exam is between 87% and 95% accurate, depending on the test format utilized by the qualified examiner.

Independent research conducted by some of the nation's top scientists concluded that, while the polygraph technique is not infallible, research clearly indicates that when administered by a competent examiner the polygraph test is the most accurate means available to determine truth and deception

.“Polygraph is the most accurate means available for determining the truth or deception of a person answering a direct question.”

Since 1980, a compendium of research studies - encompassing 80 research projects involving 6,380 polygraph examinations and 12 studies of the validity of field examinations following 2,174 field examinations, indicate an average accuracy rate of 98%.

Contrary to popular belief, polygraph results are admissible in most courts across the country. The states of New Mexico and Ohio have allowed Polygraph to be admitted, even over objection of the opposing party.

The Supreme Court has left it up to individual jurisdictions to allow or disallow the use of polygraph examinations. There are only four (4) states that have a total ban on admitting polygraph results. Most states allow them if both the plaintiff and the defendant have agreed (stipulated) that the results of the test will be admissible prior to the examination being conducted. They are admitted more frequently in civil trials than criminal trials. For more details on admissibility and case citations for each state, visit: Source: American Polygraph Association

WILL I KNOW WHAT THE QUESTIONS ARE PRIOR TO THE TEST? Yes. There are no surprises on a polygraph examination. During the pre-test phase, the examiner will review all elements of the examination and review the test questions with you prior to administering the examination.

Yes! After the examination, the examine will be given a verbal confirmation of the outcome. If requested, a written report will follow.

The simple answer is no All examines have some type of general nervous tension. It is normal to feel nervous when going into a new situation. While a person's heart beat and respiration rate may increase when he, or she is nervous, a qualified examiner understands this situation and will take it into consideration when evaluating an
examine's response. During the pre-test phase, the examiner will review all elements of the examination and review the test questions prior to administering the examination. By this time, the truthful examine will be a bit more relaxed; nervousness will not cause the innocent examine to be shown deceptive.

In addition, unlike general nervous tension, an examine's reaction to deceptive responses is highly specific. An examiner mitigates a nervous response by reviewing the questions with the examine and through an acquaintance or "practice test" prior to the exam.

Some medications and medical conditions can influence physiological responses and diminish tracings recorded on the charts, but they do not produce erroneous outcomes. Examines should continue taking medications as prescribed by doctors. If you are taking medication, notify your examiner so an assessment can be made.

WHAT DOES A TYPICAL POLYGRAPH EXAMINATION ENTAIL? Prior to conducting a polygraph examination the polygraph examiner will review the facts of the case. He then will determine the best test format to use and formulate the specific test questions based upon the information provided.

A professional polygraph examination has three phases: a pre-test phase, an in- test phase, and a post-test phase, which includes test data analysis. A typical polygraph examination will last at least two hours, and frequently longer.

Pre-test ~ In the pre-test phase, the polygraph examiner will complete required paperwork and talk with the examine about the test. The examiner will review the facts of the case. At this time the examiner will read each question to the examine to make sure each question is easily understood. The examiner will also familiarize the examinee with the testing procedure and the polygraph instrument.

In-Test ~ The in-test (chart collection) phase, the examine is attached to the polygraph instrument sensors and given additional instructions. The examiner will ask the examine the previously reviewed questions. All of the questions are designed to be answered yes or no.

The questions will be asked several times while the examine is attached to the instrument and data is collected via the sensors and are recorded in the form of polygraph charts.

Post-Test ~ Following the in-test phase, the examiner will analyse the data on the charts. The examiner will numerically score the charts, following the standards set for that test format. The examiner will then render an opinion as to the truthfulness of the person taking the exam. The examiner, when appropriate, will offer the examine an opportunity to explain physiological reactions in relation to one or more questions asked during the polygraph examination.

The examiner will transmit the test results to the client verbally As soon as is practical, a written report will be provided if requested.

Before hiring a polygraph examiner, always find out about their credentials and experience. You should ask a lot of questions, such as the following:
How long have they been a polygraph examiner? How many polygraph examinations have they administered?
How many professional polygraph associations do they belong to? Have they qualified as an expert polygraph witness? How often do they attend continuing education courses?
If they are experienced and truly professional, they will want you to know about their qualifications.
First, you should confirm that they are licensed (if state required) and insured.

Make sure the examiner has attended an approved polygraph training school. A professional polygraph training program will last a minimum of 7 to 10 weeks. Upon completion of this training the examiner must complete an internship by conducting a certain number of exams under the guidance of an experienced examiner. Upon completion of the internship period, the polygraph school will review the examiner's work and determine if the examiner meets their requirements for certification.
Also, assure the examiner belongs to professional organizations. Ask if he/she is a member of the American Polygraph Association, the American Association of Police Polygraphists, and/or one of their affiliate state associations. These professional organizations require their examiners to have extensive training at an approved polygraph school and continually study the latest truth detection technology and techniques through continuing education. These professional organizations also award advanced certifications. Examiners attend advanced training in specific fields of study, such as Post Conviction Sex Offender Testing and Criminal Evidentiary Examinations
These organizations also govern the conduct of its members by requiring adherence to a code of ethics and a set of established standards of practice

As stated earlier, if the examiner is experienced, and truly professional, he/she will want you to know their qualifications. The examiner will gladly provide you with this information. If this information is not readily available – Ask! The last thing you need is to spend your money on an inaccurate polygraph test. Test results that are inaccurate can cost you a lot more than your money. It can cost you your job, your relationship, your reputation, or in criminal matters.... harm your defence! Always ask for examiner credentials and experiences.

An inconclusive or no opinion result simply means that insufficient data is available for the examiner to render a definitive opinion of deception, or no deception. In such cases a second examination is usually conducted in an effort to arrive at a decision. The classification of a polygraph examination as "inconclusive" is a protection for the examine. It a safeguard to protect the examine from being falsely identified as deceptive when inadequate data is collected. Critics of polygraph have wrongly classified inconclusive test results as errors. In actuality, a determination of inclusive is made to avoid errors in identifying truthfulness or deception of an examine.

All test questions must be limited to "yes" or "no" answers. The test questions must have definite objective answers and may not be opinions. The test questions must relate to past events of a factual nature. The wording of the questions must only have one interpretation.
There are never any questions pertaining to religion or politics. There will be no questions pertaining to sexual subject matter during either the interview or polygraph examination unless such subject matter is relevant or necessary to conduct the investigation.

Polygraph examinations are used to protect the public, to verify the truth, to identify the innocent, to determine deception; and to help identify the guilty.

Polygraphs are most commonly used for criminal and civil matters, government and law enforcement pre-employment screening, homeland security, commercial theft investigations, and to monitor convicted sex offenders being supervised by probation and parole, and while under treatment.

Private parties also request polygraph examinations to help resolve personal matters.

Yes, under certain conditions. Generally for private employers, the Employee Polygraph Protection Act (EPPA) of 1988 requires, at a minimum, the following three criteria be met prior to requesting an employee submit to a polygraph examination:

1) That the employer has suffered a specific economic loss of money or merchandise and the loss has been reported to the appropriate authorities; 2) That the employee to be tested had access to the missing property or loss; 3) And, that the employee is suspected of involvement in the missing property or loss beyond mere access.
Exemptions granted by EPPA allow polygraph examinations for federal, state, and local government employees, as well as, employees of banks, hospitals, nursing homes, drug warehouses, armorer car companies, and law enforcement agencies.

For further information contact the American Polygraph Association at the following web site:

Frequently Asked Questions

When anyone is planning to do something they have never done before, It is normal to be curious, concerned, apprehensive,or even nervous; that is normal. The following is a list of questions people usually ask. Hopefully the answers will help alleviate some of your anxiety. The question most people want to ask, but are afraid to ask the polygraph examiner is “how do I pass a polygraph test?” The answer is very simple “Tell the truth!” If you do, you will have nothing to worry about. Your examiner will explain how the polygraph works and answer all you questions, before the administered.