How The Polygraph Became Trusted Despite Validity Issues


Since its U.S. debut, the lie detector has been a persistent but extralegal feature of our juridical culture, says the Washington Monthly. “The device has been derided by teams of experts as junk science, hardly more reliable than methods of pure chance, barred from the courts, a favorite tool of overzealous investigators and an instrument of state-sponsored vigilantism,” says the magazine in a review of Ken Alder’s book, “The Lie Detectors.” By the time scientific scrutiny finally caught up to the device in the late 1980s, generations had been seduced by it, says the Monthly.

For decades, the polygraph was a trusted tool of justice, treasured by beat cops and internal affairs investigators, celebrated across popular culture as an unerring arbiter of honesty and public virtue, used to test patients in psychiatric hospitals and job applicants in corporate interviews. The book explores how this happened, despite findings like a 1951 estimate of the error rate of polygraph readings as high as 40 percent and a 2003 report from the National Academy of Sciences that no scientific study of any rigor had been published demonstrating the validity of the polygraph test.


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