Inventions Ahead of Their Time: Lie Detector
CREDIT: Gabriel Rodr
The truth may be beauty, but extracting it can get very ugly.
The best interrogators rely on wit and persuasion to snare criminals, either tangling them in their own lies or milking a sordid compulsion to confess. Inevitably, the stubborn cases persist and most cultures have found a way to deal with them. Bedouins resort to a practice called "Bisha'a." The suspected criminal pulls a spoon from a clod of embers, licks it three times then offers up the tongue for inspection. If the flesh scars and bubbles, a guilty verdict is declared.
American law enforcement has developed a lie-detection ritual of its own: the polygraph test, which uses physiological measurements to determine the reliability of a suspect. Although use of the tool is quite new, the method and technology behind the polygraph has been around for centuries.
One of the primary figures behind the development of the lie detector, according to forensic scientist Jim Fisher, was a Harvard psychologist named William Marston. Later in life, Marston would invent the comic book character, Wonder Woman, whose "lasso of truth" could extract honesty from any man. But Marston spent the 1930s investigating the hard science of lie-detection, interviewing subjects while monitoring their vital signs . His first lie detector was simply a blood pressure cuff.
As Marston accumulated evidence, people in law enforcement took notice, including a medical student named John Larson. With support from the Berkley chief of police, Larson built the first polygraph machine. It was as big as a coffin and weighed thirty pounds, but the machine could record both blood pressure and respiration on a continuous graph, and for the first time, provided a way to reasonably test scientific theories of lie detection.
The field quickly splintered into competition. Larson continued running trials and accumulating evidence. Meanwhile, a former colleague named Charles Keeler, tried to gain public approval of the device by showing it off in petty demonstrations that combined science with card-trick magic.
By increments, their feuding resulted in a more reliable device. Keeler added a component that recorded the electrical conductance of the interviewee's skin and by 1943, according to Fisher, hundreds of companies in the United States were using the polygraph to screen employees. Today, that's illegal, and the polygraph continues to draw fierce criticism even as police and government agencies continue to use it.
This article is part of an ongoing series about inventions that arrived before the public was ready to accept them. You can read the rest of the series here.
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