A polygraph (popularly referred to as a lie detector) is an instrument that measures and records physiological changes in blood pressure, pulse, respiration, and skin conductivity while the subject answers a series of questions, in the belief that deceptive answers will produce physiological responses that can be differentiated from those associated with non-deceptive answers.
Polygraph testing can be successfully employed
- To verify the statements of victims
- To establish the credibility of witnesses
- To evaluate the truthfulness of suspects and to help exonerate the innocent who is surrounded by circumstantial or uncorroborated evidence.
- To hire and select potential employees (pre-employment screening)
- For security clearance of potential employees
- For the surveillance of employees working on sensitive positions
- For the detection or deterrence of spying in military and intelligence communities
- To solve domestic disputes such as spouse cheating or infidelity
- For solving disputes over property and business matters
- By employers and companies on issues of employee theft
- To detect and deter computer and other workplace crimes like fraud, corruption, collusion with vendors/suppliers, sabotage, theft of corporate.
- Based on the studies now available, experts assess the accuracy of polygraph examinations administered by a competent examiner to be about 90%. Level of skill and experience of the examiner plays an important part in the accuracy of the examination. Comparative studies have shown that polygraph tests yield an accuracy that equals or exceeds that of many other forms of evidence.