The 1939 lie detector that tested the power of kisses


"Kiss on the lips causes the maximum reaction, swings the needle to the end of the dial."

Image: 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. Read more…

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