Mind WondersPlay

Reading PeopleLie Detection

Lie Detectors Don't Detect Lies

The polygraph measures nerves, not lies

A line jumps on a lie detector. Would you know whether the answer was false or the person just tense?

You'll find out

  • See what the machine records
  • Compare two similar reactions
  • Test the verdict against a record

Why it matters

Keep a machine’s confident-looking readout from making an accusation or a decision for you.

About 4 min7 interactive slides · 5 questionsLesson 87 · Zone 10

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More in this zone

  1. 82Lie DetectionWe Catch Liars About Half the TimeMost people spot lies only slightly better than a coin flip
  2. 83Lie DetectionLiars Don't Always Look AwayLooking away is the most famous sign of lying, and one of the least reliable
  3. 84Truth-Default TheoryThe Truth DefaultWe're built to believe people, which is why liars usually get away with it
  4. 85InterviewingAsk Them to Tell It BackwardsLying is mentally hard; telling the story backwards makes it harder
  5. 86InterviewingToo Much Detail, or Too Little?True stories tend to be richer in details you could actually check
  6. 88LyingEverybody Lies a LittleThe average person tells about one or two lies a day, mostly small
  7. 89DevelopmentWhy Kids Start LyingA toddler's first lie is a sign their brain is growing up
  8. 90InterviewingThe Unexpected QuestionLiars rehearse their answers; they don't rehearse the question you didn't ask