A type of polygraph sometimes used in police interrogations to detect untrue or deceptive answers by recording involuntary stress-induced physiological responses, typically including changes in galvanic skin response (GSR), respiration rate, blood pressure, and heart rate. Responses to test questions relevant to the crime or matter at issue are compared with responses to unrelated control questions, and the most advanced polygraph lie detectors incorporate computer software, based on data from confirmed polygraph test results, designed to analyse the waveforms and eliminate subjectivity from their interpretation. The original polygraph lie detector was called the Keeler polygraph. Also called simply a polygraph. See also bogus pipeline, Chevreul pendulum, word-association test.