Since the dawn of man, humans have held a vested interest in knowing if their kinsmen were lying. Security, prosperity, and even survival often depend upon an accurate assessment of motivation and intent. But discovering the truth has never been easy.
One of the earliest accounts of lie detection occurs in the bible. Two women asked King Solomon to determine which was the mother of a baby boy. The women each argued their cases, but neither admitted to stealing the other's child. Finally, Solomon requested a sword. He would cut the baby in half, he explained. That way each woman could have a part of it.
The liar encouraged Solomon to sacrifice the child so that neither woman could have him.
The true mother, however, pleaded with the king to give the baby to her rival. "I love him," she said. "Please don't kill him. Give him to her." And with this act of selflessness, Solomon knew the child was hers.
In medieval Europe, the practice of "trial by ordeal" harmed as many truth sayers as it did guilty. Ordeals included walking on hot coals, scalding by boiling water, and consuming poisons. Judges believed God would protect the innocent from pain or death, thereby proving their virtue. During the 12th century, trials by ordeal fell from public favor - but they were reinstated during the witch hunts of the 16th and 17th centuries.
The Chinese had a unique means of discovering the truth. They placed rice in the mouth of the accused during questioning. If it was spit out wet, the subject was declared honest. If the rice was still dry, it was proof of deceit.
In India it was once believed that one's big toe moved when one lied.
By the 20th century, lie detection became the pursuit of scientists. Hugo Munsterberg, born in Germany in 1863, finished his career as a professor of psychology at Harvard. In the 1890s, he developed the notion that raised blood pressure correlated to dishonesty. Based on this theory, one of his students, William M. Marston, created an apparatus to measure systolic blood pressure. According to Munsterberg and Marston, they tested 1,000 Harvard students to prove the machine's ability to determine veracity.
In one of those strange happenstances of life, Marston (who, while at Harvard, won the Edison Prize for Film Scenario) went on to create the comic book hero Wonder Woman. Her most powerful weapon, a magic lasso, forced villains to tell the truth.
University of California, Berkeley, student John A. Larson was the next to improve upon lie detection technology. His "cardio-pneumo psychogram," invented in 1921, measured not just blood pressure, but also pulse and respiration. And, unlike Marston's machine, Larson's provided constant monitoring and recorded the results.
Larson was the only polygraph inventor to ever actually work with the police. Berkely Police Chief August Vollmer believed so strongly in the young man's creation that his became the first police force to use lie detection in investigations. It fit Vollmer's conviction that police work should incorporate modern technologies, whenever possible. It was Vollmer who first insisted police have college degrees. Due to his urging, UC Berkeley created a criminal justice program in 1916.
As Larson was Vollmer's protege, Leonarde Keeler was Larson's. It is Keeler who is today most closely associated with the invention of the lie detector, for several reasons. Firstly, Keeler made lie detectors portable, and added the ability to capture "galvanic skin response" - fluctuations in the body's electromagnetic field. Secondly, Larson was a tactless, unlikeable man, by many accounts, who made more enemies than allies. Lastly, Larson felt his (and other) lie detectors should be restricted to scientific use by properly trained administrators. Conversely, Keeler immediately recognized the commercial value of both the machines and their capabilities. He patented his invention, a fact that incensed Larson. A natural promoter, Keeler publicly demonstrated his polygraph around the U.S. His most famous stunt was guessing what playing card a testee was holding.
But it wasn't just competition or a flawed personality that diminished Larson's accomplishments. In 1922, the San Francisco police department used Larson's machine to interview suspected murderer Henry Wilkens. They believed he killed his wife Anna. But, according to Wilkens' version of events, she was shot by "automobile bandits" while the family rode in their car. Larson's equipment found Wilkens to be honest. Based on this, the press pronounced him innocent of any involvement in the murder.
As time went on, though, other damning facts surfaced. A man came forward to say that Wilkens hired him and his brother to kill Anna. Then, an affair between Wilkens and Anna's sister came to light. Eventually, Wilkens was arrested and tried. Larson's lie detector results not withstanding, the public was shocked when the jury found Wilkens not guilty. Larson began to worry that he had indirectly helped a murderer go free. Later, knowing he could not be tried twice for the same crime, Wilkens agreed to another form of lie detection. He was administered "truth serum" and again asked about the crime. Larson and other witnesses to the test discovered that Wilkens could still lie - even during drug-induced "twilight sleep." More critically, Larson realized that lie detectors could be outwitted.
Wilkens' was just one case that proved lie detector results could be both inaccurate and erratic. Still, in 1997, the U.S. Court of Appeals for the Armed Forces argued that exclusion of polygraph evidence violated the Constitutional right to present a defense. The U.S. Supreme Court disagreed. They ruled that "unlike other expert witnesses who testify about factual matters outside of the jurors knowledge, such as analysis of fingerprints, ballistics, or DNA," polygraphs only supply the jury with another opinion. The court went on to say that "A fundamental premise of our criminal trial system is that the jury is the lie detector. Determining the weight and credibility of witness testimony, therefore, has long been held to... [belong] to the jury."
Today, there are states that admit polygraph results if both parties agree to allow it. Others have banned it altogether. Federal judges have the most leeway and can decide whether to admit lie detector results on a case-by-case basis.
Regardless of its legal standing, doubts will always persist about how accurately a machine can judge human integrity. And, since splitting the baby in two is no longer an option, perhaps King Solomon will remain the one man wise enough to actually separate the truth from a lie. PnC