5th Jul 2012

The Pseudoscience of Lie Detectors

More commonly known as the lie detector, the polygraph is a device that measures the changes in our nervous systems, detecting and recording heart rate, respiration, sweating and blood pressure. It allegedly operates on the premise that due to anxiety and fear, people produce involuntary physiological responses when they lie. Some claim that polygraph testing is up to 96% accurate, while others claim 50%, but it’s likely somewhere in between. Polygraphs only detect physiological responses, which don’t directly translate to proof of lying—some guilty people can remain completely calm while lying, while innocent people might produce ‘guilty’ responses. Polygraphers ask control questions to determine normal responses and balance this, but the tests are therefore inherently subjective because a human interprets the results. The ‘base rate fallacy’ also causes considerable problems, involving ignoring statistical information and not taking into account the frequency of what’s being tested for. For example: using the 96% accuracy rate, suppose that statistically, 1 in 10,000 people are terrorists—but if 10,000 people are randomly polygraphed, 1 terrorist and 400 false positives will be turned up, so the 96% accuracy isn’t useful or meaningful. Polygraphs are used as a tool for psychological bullying rather than accuracy, intimidating suspects into confessing—and they are, therefore, a pseudoscience.

This post has 89 notes
  1. lovenotherbruizes reblogged this from sciencesoup
  2. cegd reblogged this from sciencesoup
  3. thefunboost reblogged this from midnight-coven
  4. midnight-coven reblogged this from sciencesoup and added:
    Finally! Someone wrote it here. It’s flabbergasting how Americans think these devices actually determine such a thing....
  5. knowledge-yay reblogged this from sciencesoup
  6. thereisnonamehere reblogged this from sciencesoup
  7. bonitoboy reblogged this from sciencesoup
  8. cabaline1 reblogged this from sciencesoup
  9. misalkthorpay reblogged this from sciencesoup
  10. rubedox reblogged this from sciencesoup
  11. howling-wulf reblogged this from sciencesoup
  12. gooseandjewels reblogged this from sciencesoup
  13. pragmacattick reblogged this from sciencesoup
  14. biancabloomingdale reblogged this from sciencesoup
  15. obscurecity reblogged this from sciencesoup and added:
    The Pseudoscience of Lie Detectors More commonly known as the lie detector, the polygraph is a device that measures the...
  16. socialbutterfingers reblogged this from sciencesoup
  17. flippant-rejoinder reblogged this from sciencesoup
  18. lizhasthoughts reblogged this from sciencesoup