LS327 Lecture 8: The Police Use of the Polygraph in Criminal Investigations
13 Feb 2019
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Ls 327 - lecture 8 - the police use of the polygraph in criminal investigations. Lie detector , scientific diagnostic instrument, records physiological changes in the subject, three measures: Blood pressure cuff (changes in blood pressure and heart rate) Pneumograph tubes placed around chest and stomach (record changes in breathing) Electrodes attached to fingers (changes in skin involves trickery and deception look for someone with an undergraduate degree, investigative background, interrogation skills, etc. Polygraph is voluntary, truthful people would take it (don"t want to be a suspect, assit the police) for a guilty person: feel that if they say no, will get suspected, maybe they can beat the test. 30% of subjects who agreed to take the test later changed their minds, most cancellation. Examination procedure legal issues: admissibility, not admissible in criminal court in canada. Occasionally accepted in civil court (only in exceptional instances) Use in on occasion with guilty people to get them to confess which is admissible.
