The truth shall set you free [development of the polygraph]

Originally called the "Lie Detector" and sometimes the "Lie Box," the polygraph does not detect lies, it detects emotional responses. In other words, the polygraph is a multichannel recorder that displays respiration, the pressure in a partially inflated arm cuff (which indicates a change in blood pressure and pulse rate), and a change in skin resistance. The history and the value of the polygraph are discussed. Although not providing admissible evidence in court, the polygraph has a role as a useful tool in directing an investigator where to seek further information. Equally as important as the development of the technology was the development of the type of question to be asked. If polygraphic information is not admissible as legal evidence, what value is the examination? There are three principal benefits: 1) it can eliminate a subject as a suspect, 2) the answers to questions can indicate in which direction further information is needed, and 3) the willingness to undergo an examination conducted by an approved, experienced examiner, chosen by a law-enforcement agency, provides evidence that the suspect has nothing to conceal. However, beyond its use in criminal investigation, it is widely used as a screening tool by employers.