• What is a “Polygraph”?

    The term "polygraph" literally means "many writings." The name refers to the manner in which selected physiological activities are simultaneously recorded. The polygraph is an instrument that simultaneously records physiological measurements such as blood pressure, pulse rate, respirations, electro dermal (sweat) activity and other readings, while the subject is asked questions pertaining to a specific issue or set of issues under investigation.

  • How accurate is the polygraph?

    A meta-analytic survey conducted by the American Polygraph Association in 2011 concluded hat techniques intended for event-specific (single issue) diagnostic testing produced an aggregated decision accuracy of 89% with an estimated inconclusive rate of 11%. The Utah Zone Comparison Technique produced decision accuracy of 93%. Polygraph techniques in which multiple issues were encompassed produced an aggregated decision accuracy of 85% with an inconclusive rate of 13%. These findings were consistent with those of the National Research Council’s (2003) conclusions regarding polygraph accuracy, and provide additional support for the validity of polygraph testing when conducted in accordance with APA Standards of Practice.

    While the polygraph technique is not infallible, research clearly indicates that when administered by a competent examiner, the polygraph test is one of the most accurate means available to determine truth and deception.

    This percentage is higher than other forms of evidence, including psychiatric opinions, suspect identification as provided by victims and witnesses, and fingerprint identification.

    Thus, polygraph examinations have great value and utility for various uses in the criminal justice system. However, a valid examination requires a combination of a properly trained examiner; a polygraph instrument that records as a minimum cardiovascular, respiratory, and electro dermal activity; and the proper administration of an accepted testing procedure and scoring system.

  • What does a typical polygraph examination entail?

    A typical polygraph examination will include a pre-test interview phase, a chart collection phase and a test data analysis phase. The typical polygraph exam will generally last 2 – 3 hours from beginning to end.

    In the pre-test, the polygraph examiner will discuss the test questions so that the examinee fully understands each question in advance of taking the polygraph examination. The examiner will also explain the polygraph testing process and answer any questions or concerns. During the chart collection phase, the examiner will administer and collect a number of polygraph charts. The exam will take place in a quiet room with only the polygraph examiner and the examinee present to prevent distractions. The examiner will attach sensors to the examinee and ask simple “yes” or “no” questions that were reviewed in the pre-test phase. Following this, the examiner will analyze the charts and render an opinion as to the truthfulness of the person taking the test. The examiner will offer the examinee an opportunity to explain physiological responses to 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 and have not been shown to have scientific support.

  • Can being nervous cause someone to “fail” a polygraph examination?

    It is very common to feel nervous during a polygraph examination. Nervousness is a generalized condition that exists throughout the entire exam, not just on one or two questions. Because nervousness exists during the entire test process, it will not affect the test score. A well trained polygraph examiner can evaluate the difference between a nervous reaction and a reaction caused by a deceptive answer to a question.

  • What if I have another question?

    Cuesta Polygraph encourages you to email or call our office for questions specific to your situation!