Tech Time Warp: The Truth About the Polygraph

Posted by Kate Johanns on Feb 3, 2017 11:00:00 AM

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polygraph machine.jpgWe cannot tell a lie: The polygraph has a fascinating history.

On Feb. 2, 1935, Leonarde Keeler had his first opportunity to use a polygraph in a criminal trial. Keeler had devoted nearly a decade to perfecting the machine—first invented by his mentor John Larson—before putting it to the test before a jury.

Wisconsin Judge Clayton F. Van Pelt was faced with a case involving only circumstantial evidence, so he sought the assistance of Northwestern University’s Scientific Crime Detection Laboratory. The country’s first forensic lab, it had been established in 1929 following the St. Valentine’s Day Massacre. Keeler worked there, tweaking the polygraph, a machine that measured skin response and blood pressure during questioning in order to devise whether a subject was lying. Van Pelt had Keeler question defendants Tony Grignano and Cecil Loniello, who had been accused of killing a sheriff, and the results persuaded the jury to convict.

Modern polygraphs

According to the American Polygraph Association, a modern polygraph collects data from at least three physiological systems at once—generally respiratory, cardiovascular, and integumentary. (The integumentary system includes the sweat glands.) Although law enforcement, government agencies, attorneys, and some employers rely on the polygraph, many jurisdictions no longer allow the use of polygraph evidence in court. Results are simply too inconsistent. At the end of the day, the outcome of a polygraph test depends on the skills and communication style of a human questioner, so there’s no way to completely standardize testing.

Keeler passed away in 1949 and did not live to see his invention’s accuracy called into question. After his invention gained notoriety, he founded the Keeler Institute, where he trained polygraph examiners and served as an expert witness. His invention even landed him a spot in Hollywood lore: He played himself in Call Northside 777, a 1948 film noir starring Jimmy Stewart.

Intronis blog

Tech Time Warp is a weekly feature that looks back at interesting moments and milestones in tech history.

Photo: Federal Bureau of Investigation via Flickr. Used under CC 1.0 License.

Topics: Tech Time Warp

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