In order to assess a person’s sincerity, a professional polygraph service—also referred to as a lie detector test—uses autonomic nervous system responses.

The Fundamental Testing Stages-Three separate, required steps make up a typical polygraph service:

Interview Prior to the Test: The examiner establishes rapport, goes over the specific questions to be asked, explains how the equipment operates, goes over the case’s factual background, and obtains the examinee’s signed consent.

The actual physiological monitoring occurs during the in-test examination. The examiner asks a controlled combination of pertinent and control questions, repeating them several times in different orders to establish baseline values.

Post-Test Evaluation: The examiner reviews the data one last time, talks with the subject about the findings if necessary, and assigns scores to the charts.

A certified service maps ongoing physical reactions using sophisticated diagnostic sensors:

Respiration: Specialized tubes are positioned across the chest and stomach to monitor thoracic and abdominal breathing patterns.

Electrodermal Activity: Electronic finger plates are used to assess skin conductivity and sweat gland activity.

Cardiovascular Activity: A typical arm cuff is used to continuously measure changes in blood volume, blood pressure, and heart rate.