A polygraph (translated as 'many writings') is an instrument which
measures and records several body-response variables including blood
pressure, heart rate, respiration and skin-resistance while a series of
questions are being asked, in an attempt to determine the truth about a
matter.
At least four items will be attached to the examinee, and those
in turn connect to the polygraph: a blood-pressure cuff on the left arm, a
breathing measurement device at the abdomen, a breathing measurement device
at the chest, and skin-conductance measurement wires on the right
hand.