The 1939 lie detector that tested the power of kisses

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The 1939 lie detector that tested the power of kisses
Credit: HERBERT GEHR/THE LIFE IMAGES COLLECTION/GETTY IMAGES

A kiss for the lie detector

"Men are greater liars than women"

Chris Wild

1939

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"Kiss on the lips causes the maximum reaction, swings the needle to the end of the dial." Credit: Herbert Gehr/The LIFE Images Collection/Getty Images

Feb. 2, 2015 marks 80 years since a polygraph was first used to bring a conviction in a U.S. court.NYPD criminologist Roy Post invented his own version of a lie detector machine. Called the Postometer, the test theoretically detected not only criminal suspects, but also to discovered the truth, or otherwise, of people's reactions to emotional stimulus. The subjects of Post's experiments placed their hands on a pair of metal plates. Their blood pressure and temperature generated a small electrical current, indicating an emotional change had occurred. The Postometer amplified these currents and displayed their levels on its needle and dial.While the technology has improved, polygraph tests are still considered by many to be unreliable forms of evidence.

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"Needle at 50 picked 'the witness' in our experiment and (below) at 150, picked 'the thief.'" Credit: Herbert Gehr/The LIFE Images Collection/Getty Images
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Credit: Herbert Gehr/The LIFE Images Collection/Getty Images
The most meaningless thing in the world is the act of two women kissing. That does not even make the needle quiver. - Roy Post, 1939
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"Needle hardly moves because this man did not steal the briefcase in our experiment." Credit: Herbert Gehr/The LIFE Images Collection/Getty Images
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"This man looked guilty, but the detector proved he was innocent." Credit: Herbert Gehr/The LIFE Images Collection/Getty Images
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"Kiss on the forehead creates little emotion, as shown by small movement of needle." Credit: Herbert Gehr/The LIFE Images Collection/Getty Images
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