Why the Creator of One of the First ‘Lie Detectors’ Lived to Regret His Invention

In order to catch liars, the ancient Chinese would sometimes give the accused a mouthful of uncooked rice during interrogation—and then ask the person to open wide. Dry rice would indicate a dry mouth, considered evidence of nervous guilt—and sometimes grounds for execution.

The notion that lying produces observable physical side effects has stuck with us, and one man thought he’d cracked the science of lie detection in the 1920s, amid a truly modern boom in crime. This was the era of Prohibition, dominated by bootlegging gangsters—Chicago alone was said to be home to 1,300 gangs—and some police departments adopted increasingly brutal tactics to wring the truth out of suspects: beating and burning detainees with cigarettes, or depriving them of sleep. Unconstitutional but widely applied across the nation, according to a major report commissioned by then-President Herbert Hoover, these techniques did result in confessions—many of them highly dubious. 

One police chief in California thought he could usher in a new era in which science would make the interrogation process more accurate and humane. August Vollmer of the Berkeley Police Department was a committed reformer who began recruiting college graduates to help professionalize the force. His interests dovetailed with those of John A. Larson, who had recently received a PhD in physiology from the University of California, Berkeley, and had a passion for justice. Larson joined the Berkeley force in 1920, becoming the first rookie in the country with a doctorate. 

Vollmer and Larson were particularly intrigued by the possibilities of a simple new deception test pioneered by William Marston, a lawyer and psychologist who would later earn fame as the creator of Wonder Woman, with her famous Lasso of Truth. (Marston unofficially used the test on some criminal defendants during probation proceedings.) Larson spent punishing hours creating a far more sophisticated test, tinkering in his university lab on an odd-looking assemblage of pumps and gauges that he would attach to the human body using an arm cuff and chest strap. His device would measure changes in pulse, respiration and blood pressure all at once, during continuous monitoring of a subject under interrogation. Larson believed the contraption would flag false answers via distinct fluctuations etched by a stylus onto a revolving drum of paper. An operator would then analyze and interpret the results. 

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By the spring of 1921, Larson unveiled the machine he called a cardio-pneumo-psychogram, and later simply a polygraph, a nod to the multiple physical signals recorded by the stylus. A San Francisco Examiner report later said it looked like some mix of “a radio set, a stethoscope, a dentist’s drill, a gas stove” and more, all arranged on a long wooden table. However ramshackle it appeared, Larson’s innovation, with its continuous battery of measurements, leaped beyond all previous attempts to track the body’s involuntary responses. In a frenzy of sensationalist reporting, the press dubbed Larson’s polygraph a “lie detector,” and the Examiner swooned: “All liars, regardless of cleverness, are doomed.” 

Larson himself didn’t quite buy the hype. As he tested the invention, he found an alarming error rate and grew increasingly concerned about its official use. And while many departments across the country embraced the device, judges proved even more skeptical than Larson. As early as 1923, the U.S. Court of Appeals for the District of Columbia ruled polygraph results inadmissible at trial because the tests were not widely accepted by relevant experts. Still, cops kept using the machine. Larson watched in dismay as a former colleague patented an updated version of the idea in 1931. 

While Larson’s original machine collected dust, imitators with sleeker modern versions proliferated, all hewing roughly to the same parameters as Larson’s—and millions of people were subject to testing. During the Cold War, the State Department used polygraph tests to oust alleged Communist sympathizers and gay employees from the federal government. Many innocent government workers lost their livelihoods, while others who were eventually exposed as treasonous—including the infamous spy Aldrich Ames—managed to dupe the tests. For his part, Larson got a medical degree and spent his remaining career as a psychiatrist. Yet he was forever soured on the polygraph, eventually describing the device as his very own “Frankenstein’s monster,” unable to be controlled or killed. 

In 1988, Congress finally passed a law generally banning private employers from requiring the test, though some government agencies still turn to it for screening, and police may use it on suspects as an investigative tool under certain circumstances. 

“It’s an instrument of great hope but also great pain,” says Kristen Frederick-Frost, curator of modern science at the National Museum of American History, where Larson’s original polygraph anchors an exhibition, “Forensic Science on Trial,” open through next summer. In the 1930s, the Berkeley Police Department almost tossed the machine in the trash, but Vollmer thought it might one day have historical value and saved it. In 1976, the Berkeley Police Department donated it to the Smithsonian, where it sat in storage for decades. Over the past five years, seven conservators have helped to revive its motley parts for display. Some of the rubber and plastic had become stiff and degraded. Other parts were fragile, grimy or missing. The paper was seriously compromised. Today, though, “it doesn’t look like an old dusty thing that nobody cares about,” says Janice Stagnitto Ellis, the museum’s paper conservator. “It looks vital.” 

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Susan Saulny is a freelance journalist who previously reported for the New York Times and Washington Post.