What a polygraph measures
Polygraphs chart out blood pressure, breathing rate and sweat production to help an examiner determine whether a subject may be lying. The LX4000, produced by Lafayette Instrument, displays both raw sweat production data and an adjusted chart designed to be easier to read. There are concerns that the adjusted chart, produced in "auto" mode may be introducing inaccuracies.
Sensors measure body changes as subject answers yes-no questions; data recorded on computer. Hover over the numbers below for more information.