Add Yahoo as a preferred source to see more of our stories on Google. American inventor John Larson, right, demonstrates the operation of a polygraph at Northwestern University in Evanston, Illinois, ...

The polygraph is not a lie detector but rather an instrument that measures a person’s physiological changes to questions posed by the examiner. An elevated physiological response to a particular ...

A version of this story appeared in CNN’s What Matters newsletter. To get it in your inbox, sign up for free here. When President Ronald Reagan’s White House threatened thousands of government ...