polügraaf

Polügraaf, commonly known as a lie detector, is a device that measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while a person is questioned. The theory behind its use is that deceptive responses will produce physiological reactions that are detectable and different from those associated with truthful responses.

The instrument typically consists of a series of sensors attached to the subject. Pneumographs are used to monitor breathing rate and depth, cuff on the arm measures blood pressure and pulse, and electrodes on the fingers measure skin conductivity (galvanic skin response). A polygraph examiner asks a series of questions, some neutral, some relevant to the matter under investigation, and some designed to elicit a baseline response. The examiner then analyzes the recorded physiological data to determine if the subject's responses to relevant questions differ significantly from their responses to neutral questions or from their established baseline.

The validity and reliability of polygraph results are a subject of ongoing debate. While some studies suggest a degree of accuracy, many scientific and legal bodies have raised concerns about the scientific basis of polygraph testing and its potential for error. Its admissibility in court varies significantly by jurisdiction, and it is often not permitted as evidence due to its controversial nature and the lack of standardized testing protocols. Despite these limitations, polygraphs continue to be used in some law enforcement, intelligence, and pre-employment screening contexts.