Polygraph
Polygraph
A Polygraph (pronounced: /ˈpɒlɪɡrɑːf/), often referred to as a lie detector test, is a device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a person answers a series of questions.
Etymology
The term "Polygraph" comes from the Greek words 'poly' meaning 'many' and 'graph' meaning 'writing'. It was named so because the original machine used to record changes in blood pressure, pulse rate, and respiration on a single strip of moving paper.
Usage
The Polygraph is used as a forensic tool in law enforcement applications, particularly in investigating crimes and screening potential employees. It is also used in a range of other contexts, including psychotherapy, spouse fidelity issues, and public media for entertainment purposes.
Method
The Polygraph works by detecting physiological changes in the body in response to probing questions. These changes are believed to be signs of stress, which is often associated with lying. The accuracy of polygraph results, however, is a subject of ongoing debate.
Related Terms
- Forensic Science: The application of scientific knowledge and methodology to legal problems and criminal investigations.
- Physiological: Pertaining to the normal, healthy functioning of an organism.
- Blood Pressure: The pressure of the blood in the circulatory system, often measured for diagnosis since it is closely related to the force and rate of the heartbeat and the diameter and elasticity of the arterial walls.
- Pulse: The rhythmic contraction and expansion of the arteries with each beat of the heart.
- Respiration: The action of breathing.
- Skin Conductivity: A measure of the skin's ability to conduct electricity, which varies with its moisture level (sweating is a symptom of anxiety, hence of possible lying).
External links
- Medical encyclopedia article on Polygraph
- Wikipedia's article - Polygraph
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