Frequently Asked Questions

The term "polygraph" literally means "many writings." The name refers to the manner in which selected physiological activities are simultaneously recorded. Polygraph examiners may use conventional instruments, sometimes referred to analog instruments, or computerized instruments. It is important to understand what a polygraph examination entails. A polygraph will collect physiological data from at least three systems in the body.

Corrugated rubber tubes (or electronic sensors) placed over the examinee's chest and abdominal area will record respiratory activity. Two small metal plates or disposable adhesive electrodes, attached to the fingers, will record sweat gland activity, and a blood pressure cuff or similar device will record cardiovascular activity. Some instruments also monitor other activities. For example, a finger plethysmograph, which monitors blood volume in a fingertip, or motion sensors, which monitor general movements that might interfere with test data, are often used. 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 and have not been shown not to work any better than chance (i.e. accuracy is similar to making a decision based on a coin toss).

A typical polygraph examination will include a period referred to as a pre-test interview, a chart collection phase, and a test data analysis phase. During the pre-test, the polygraph examiner will complete the required paperwork and talk with the examinee about the test, answering any questions the examinee might have. It is during this phase that the examiner will discuss the test questions and familiarize the examinee with the testing procedure. During the chart collection phase, the examiner will administer and collect a number of polygraph charts. The number of questions and the number of charts will vary, depending on the number of issues and technique employed. Following this, the examiner will analyze the charts and render an opinion as to the truthfulness of the examinee. The examiner, when appropriate, will offer the examinee an opportunity to explain physiological responses in relation to one or more questions presented during the test.

Most polygraph examinations take between 90 and 120 minutes, the majority of which entails a standardized interview before the testing phase.  Examinations may take longer when covering complex issues.  Polygraph examinations taking less than an hour have been reported, though the shortest of examinations are often associated with unvalidated or invalid procedures. 

The four sectors that use the polygraph include law enforcement agencies, the legal community, government agencies, 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.
- The court systems in cooperation with probation and parole officers and therapists to monitor convicted sex offenders.

- Attorneys in civil litigation.

• Government Agencies

- Department of Defense Agencies
- Agencies in the Intelligence Community

• Private Sector

- 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.

It depends on the type of test being given; the science associated with a particular technique will determine the number of questions which are allowed.  Generally, examiners use between two and four questions about the test issue along with a small number of other questions included for technical reasons for a total of about 10 – 12 test questions.  Some techniques use a smaller number of questions, but those questions are repeated several times within each test so that the total number of question presentations is about 10 – 12.  The test questions are based on the answers the examinee gives during the interview, and the final wording of the test questions are negotiated between the examiner and examinee prior to the testing phase.  There are no surprise questions in modern polygraph techniques.  Based on the current science and research on validated techniques, no examiner in the world can conduct a valid test where there are more than 4 questing pertaining to the subject matter being tested.  If they say they can, they are not conducted valid testing.

Everyone who takes a polygraph examination is nervous.  It is expected.  As everyone knows, anxiety can elevate one’s heart rate, blood pressure and other physiological functions.  During polygraph testing, however, this heightened state becomes the examinee’s normal pattern.  Having a higher blood pressure does not cause a person to fail a polygraph examination.  Examiners are only interested in changes to the person’s normal pattern.  While examiners take steps to reduce the jitters most examinees experience, there is no evidence that anxiety itself causes truthful people to fail or deceptive people to pass polygraph testing. 

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, governmental agency that requested the examination, and others as may be required by law.

There are different types of techniques that can be used during a polygraph exam.  The technique used by the examiner will be determined on the type of testing that's being conducted.  With that, different techniques have different accuracy ratings.  Research shows that polygraph examinations have an accuracy rate of up to 97%.

As with any test involving humans, there is always a possibility of error, this is why polygraph exams are not 100% accurate.  In fact, no test is 100% accurate.  Human error exists with any test.  

For a polygraph test, the human error could be one or a combination of things.  Errors could be because the examiner fails to properly prepare the examinee for the examination.  This is why exams should last at least an hour and a half.  Another example of error could be the examiner misreading the physiological data on the polygraph charts.

Since it is recognized that any error is damaging, examiners utilize a variety of procedures to identify the presence of factors that may cause errors or an unbiased review of the polygraph records.

(Information obtained from the American Polygraph Association)

We are located at 909 E. Cornerview Street in Gonzales, Louisiana.  Our parent company, NOLA Polygraph, has an office in Luling, Louisiana.  We will travel to your location for testing for an additional fee, which is determined on a case-by-case basis. Exams are conducted by appointment only.