A polygraph, a device or procedure that measures and records several physiological indicators, such as blood pressure, pulse, breathing, and skin conductance, while a person answers a series of questions. The use of the polygraph is based on the belief that false answers will cause physiological reactions that can be distinguished from reactions associated with truthful answers; However, there are no specific physiological responses associated with lying, making it difficult to identify the factors that distinguish those who lie from those who tell the truth.