Polygraph first used to convict criminals,
February 2, 1935
Jessica MacNeil - February 02, 2017
It has long been believed that lies could be detected by paying attention to physiological reactions
when someone is questioned, but it wasn't until the 1920s that a device was created to do the job.
It's reliability is often debated, but the polygraph measures a subject's physiological activities like
blood pressure, pulse, respiration, and skin conductivity to try to determine if they are answering
questions honestly. Pens record impulses on moving graph paper driven by a small electric motor so
the results can be analyzed.
John Augustus Larson, a medical student and officer at the Berkeley Police Department in California,
invented the cardio-pneumo psychogram in 1921, a device that monitored systolic blood pressure
and breathing depth, and recorded it on smoke-blackened paper.
Larson's protege Leonarde Keeler worked at the
Berkeley Police Department in high school and was
fascinated by Larson's machine. After graduating from
college, Keeler sought to improve the lie detector. He
built a device called "The Emotograph," but it was
destroyed in a fire in 1924.
Keeler (seen setting up a polygraph in the photo) then
worked on a new instrument with the help of the
Western Electro Mechanical Company. The new
machine used an ink polygraph system, and had
mechanical metal bellows, a motor drive, a
pneumograph to go around the chest, and a mechanical
indicator that would mark data on graph paper. This
machine was the first mass-produced polygraph.
Keeler continued to improve the device, adding
galvanic skin response to measure the electrical
conductance of the skin, and patenting an "apparatus
for recording arterial blood pressure" in 1931. Soon
after his polygraph was sold to the FBI as a prototype.
In 1935 Keeler got to put his machine to the test on two accused criminals in Portage, Wisconsin.
The results of his test were submitted as evidence in court and the subjects were convicted of
assault.
He became one of the most well-known polygraph examiners, popularizing use of the device in
criminal investigations.
Also see:
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Robotic lie detector
When your body talks, BodyMedia listens
Resolving to map the brain: resolution, resolution, resolution
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Editor's note: This article was originally posted on February 2, 2015 and edited on February 2,
2017.