For decades psychologists and law enforcement officials have argued about the validity of lie detectors. Some think that it’s an infallible technology, while others believe that master criminals can manipulate the results.

The first modern lie detector was created by Cesare Lombrosso in 1881. John Larson and Leonard Keeler would advance the technology, which is still used today.

Lombroso’s Glove

Although he was a convicted felon, Cesare Lombroso was credited with discovering that there were specific physical characteristics associated with lying. He used a large gutta-percha glove that was hermetically sealed and filled with air on the subject’s hand while it was attached to a device that recorded changes in blood pressure.

His invention, which is referred to as the “Lombroso Glove” or the “Volumetric Blood-pressure Instrument,” was a precursor to more advanced instruments. These machines allowed for the simultaneous recording of a subject’s heart rate, blood pressure, and respiration.

It is this type of machine that is known as a polygraph. Although the technology has been criticized as ineffective and unreliable, many scientists claim that the modern lie detector can truly detect a person’s lies by measuring sweaty palms, blood pressure fluctuations, and changing in breathing patterns. But, does it really work? Like Wonder Woman, is it possible to lasso the truth from a suspect with a slick gadget?

Marston’s Technique

William Marston is sometimes credited as the inventor of the lie detector, though he always denied it. He originated a technique, not a device. His experiment was simple: He asked college students to tell either a true story written down on paper in front of them, or a false one that they had just made up themselves a few minutes earlier. Marston found that he could distinguish between the two stories by observing blood pressure fluctuations.For more info, do visit this website UK Polygraph Association.

He also relied on research by physiologist Vittorio Benussi, who’d developed a device that tracked changes in respiratory and cardiac activity over time. Vollmer encouraged Marston to combine the techniques into a system for detecting lying, and Larson picked up the idea.

Over the next decade, he worked with police departments to test his new technology. He consulted on hundreds of cases, including the Lindbergh kidnapping and the trial of a man who tried to sell his baby for $50,000.

Larson’s Device

John Larson, a 31-year-old medical student and Berkeley police officer, created the first polygraph machine in 1921. He combined a systolic blood pressure test based on work done by Harvard lawyer and psychologist William Moulton Marston with measurements of pulse and breathing to create the modern lie detector. He based his machine on the Erlanger sphygmomanometer and had it manufactured by local machinist Earl Bryant.

The device, which was dubbed “Sphyggy” by the newspaper reporters who covered Larson’s crime solving escapades in the 1920s and 1930s, measured changes in the examinee’s respiration rate, heart beat, and blood pressure to determine whether he or she was telling the truth. The original machine is now at the Smithsonian Institution in Washington, D.C.

Keeler was impressed by the device and became Larson’s protege. However, it took many years before the polygraph was widely accepted by the scientific community. Even today, serious criminals still find ways to trick the machine.

Keeler’s Polygraph

Keeler was inspired by the work of John Larson and he developed his own machine. It registered changes in blood pressure, respiration and perspiration. It could also record a subject’s galvanic skin resistance and heart rate. He was the first to simultaneously record multiple physiological responses. The device was more compact than Larson’s and he had reduced the time required for set up. He also made the paper that recorded the results less brittle and the ink more opaque. He replaced the need for smoke paper with ink, which saved on set up time and eliminated the need for shellacking.

Unlike Cesar Lombroso, who was never able to use his machine in court, Keeler got to test his device on criminals. He used it to interrogate suspects and found that a fair number of them lied. He hoped that his mechanical invention would make the coercive third degree a thing of the past. The truth is that the polygraph is far from perfect, and any conclusions made by an examiner rely on subjective interpretation.