Polygraph FAQ

Frequently asked questions about polygraph

Everything about lie detection | Tests, procedures of a polygraph test

What is a Polygraph?
Who Gets the Test Results?
What is the Scope of Test Questions and Dissemination of Test Results?
Are there Errors in Polygraph Examinations?
Who uses Polygraph Examinations?
How does a polygraph exam look like?
What is EPPA?
Who is affected by EPPA?


What is a Polygraph?

Polygraph ChartThe term “polygraph” literally means “many writings.” The name refers to the way in which selected physiological activities are simultaneously recorded. Polygraph examiners may use conventional instruments, sometimes referred to as analog instruments, or computerized polygraph instruments (CPI).

It is important to understand what a polygraph examination entails. A polygraph instrument will collect physiological data from at least three systems in the human body. Convoluted rubber tubes that are placed over the examinee’s chest and will record respiratory activity. Two small metal plates, attached to the fingers, will record sweat gland activity, and a blood pressure cuff or similar device will record cardiovascular activity.

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 Who Gets the Test Results?

According to the various state licensing laws and the American Polygraph Association’s Standards and Principles of Practice, polygraph results can be released only to authorized persons. Generally, those individuals who can receive test results are the examinee, and anyone specifically designated in writing by the examinee. The person, firm, corporation or governmental agency which requested the examination, and others as may be required by due process of law.

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 What is the Scope of Test Questions and Dissemination of Test Results?

Prohibitive Inquiries – Personal and intrusive questions have no place in a properly conducted polygraph examination. Many state licensing laws, the Employee Polygraph Protection Act, as well as the American Polygraph Association, has so stated in language similar to the following:

NO EXAMINER SHOULD INQUIRE INTO ANY OF THE FOLLOWING AREAS DURING PRE-EMPLOYMENT OR PERIODIC EMPLOYMENT EXAMINATIONS:

  • religious beliefs or affiliations
  • beliefs or opinions regarding racial matters
  • political beliefs or affiliations
  • beliefs, affiliations or lawful activities regarding unions or labor organizations
  • sexual preferences or activities

In a law enforcement pre-employment polygraph examination, the questions focus on such job-related inquiries as to the theft of money or merchandise from previous employers, falsification of information on the job applications, the use of illegal drugs during working hours and criminal activities. The test questions are limited in the time span they cover, and all are reviewed and discussed with the examinee during a pre-test interview before any polygraph testing is done. There are no surprise or trick questions.

In a specific issue polygraph examination, the relevant questions focus on the particular act under investigation.

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Are there Errors in Polygraph Examinations?

False positive, False negative – While the polygraph technique is highly accurate, it is not infallible and errors do occur. Polygraph errors may be caused by the examiner’s failure to properly prepare the examinee for the examination, or by a misreading of the physiological data on the polygraph charts. Errors are usually referred to as either false positives or false negatives. A false positive occurs when a truthful examinee is reported as being deceptive; a false negative when a deceptive examinee is reported as truthful. Since it is recognized that any error is damaging, examiners utilize a variety of procedures to identify the presence of factors which may cause false responses, and to ensure an unbiased review of the polygraph records; these include:

  • An assessment of the examinee’s emotional state
  • medical information about the examinee’s physical condition
  • specialized tests to identify the overly responsive examinee and to calm the overly nervous
  • control questions to evaluate the examinee’s response capabilities
  • factual analysis of the case information
  • a pre-test interview and detailed review of the questions
  • quality control reviews

Examinee’s Remedies

If a polygraph examinee believes that an error has been made, there are several actions that may be taken including the following:

  • request a second examination
  • retain an independent examiner for a second opinion

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Who uses Polygraph Examinations?

The three segments of society that use the polygraph include law enforcement agencies, the legal community, and the private sector. They are further described as follows:

  • Law Enforcement Agencies (Federal Law Enforcement Agencies, State Law Enforcement Agencies, and Local Law Enforcement Agencies such as Police and Sheriff’s Departments)
  • Legal Community (U.S. Attorney Offices, District Attorney Offices, Public Defender Offices, Defense Attorneys, Parole & Probation Departments, Attorneys in civil litigation)
  • Companies and Corporations under the restrictions and limitations of the Employee Polygraph Protection Act of 1988 (EPPA).
  • Private citizens in matters not involving the legal or criminal justice system.
  • Private citizens on behalf of their legal representative

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How does a polygraph exam look like?

A typical polygraph examination will include a period referred to as:

  1. Pre-test phase
  2. Chart collection phase
  3. Test data analysis phase
  4. Final report

In the pre-test, the polygraph examiner will complete required paperwork and talk with the examinee about the test. During this period, the examiner will discuss the questions to be asked and familiarize the examinee with the testing procedure.

During the chart collection phase, the examiner will administer and collect a number of polygraph charts.

Following this, the examiner will analyze the charts and render an opinion as to the truthfulness of the person taking the test. The examiner, when appropriate, will offer the examinee an opportunity to explain physiological responses in relation to one or more questions asked during the test. 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 stress are not polygraphs.

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What is EPPA?

On December 27, 1988, the Employee Polygraph Protection Act (EPPA) became law. This federal law established guidelines for polygraph testing and imposed a restriction on most private employers. EPPA is a federal US law and is therefore not applicable to European or other countries.

In Europe, Latin America there is no law prohibiting the utilization of polygraph for pre-employment. The candidate must nevertheless give his/her consent by signing the polygraph agreement form.

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Who is affected by EPPA?

This legislation only affects commercial businesses. Local, State and Federal governmental agencies (such as police departments) are not affected by the law, nor are public agencies, such as a school system or correctional institutions. In addition, there are exemptions in EPPA for some commercial businesses.

These are:

  • Businesses under contract with the Federal Government involving specified activities (e.g., counterintelligence work).
  • Businesses whose primary purpose consists of providing armored car personnel, personnel involved in the design, or security personnel in facilities which have a significant impact on the health or safety of any state. Examples of these facilities would be a nuclear or electric power plant, public water works, or toxic waste disposal.
  • Companies which manufacture, distribute or dispense controlled substances.

No private employer outside of the realm mentioned before may require a prospective or current employee to take a polygraph examination as a condition of employment or continued employment in the US.

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