The Invention of the Polygraph
The lie detector—or polygraph machine–was first created by John Augustus Larson (1892-1965), a part-time employee of the Berkley Police Department who was earning his Ph.D. in physiology at the University of California at Berkeley.
In studying interrogations taking place in the police department, Larson came up with the concept for a device that noted nervousness as indicated by changes in blood pressure and respiratory and pulse rates when a person was undergoing questioning. Larson eventually created a method for recording this information on a rolling drum of paper so a permanent record could be created and evaluated.
Though Larson was excited about the invention, he strongly believed that the order of the questions, interspersed with control questions, was as important as the device.
Building on the Work of William Marston
As with many inventors, Larson was building on the work of prior people. He had read of the work of William Moulton Marston (1893-1947), a Harvard psychologist and attorney, who believed that changes in systolic blood pressure (the first number recorded in a blood pressure reading) could reflect whether or not people were answering questions deceptively.
To record a person’s response when the heart is contracting (what gives the systolic measure), Marston used a simple blood pressure cuff and a stethoscope, recording the heart rate following each question. He would then note each reading as it occurred. It was a time-intensive, laborious process.
He began experimenting with this process in 1915, and it was the first time a systematic method was used to detect truthfulness or deception. Later Marston experimented with making separate use of a pneumograph to record respiration cycles. (Marston is perhaps better known as the creator of Wonder Woman, written under his pen name Charles Moulton.)
Larson saw that there needed to be a less laborious method for recording blood pressure and respiratory and pulse rates.
Polygraph Patent Went to Leonarde Keeler
Keeler grew up in Berkeley and began visiting the police department as a teenager. He got to know John Larson, who took him on as an apprentice. Once Keeler became a full-time employee, he began to test ways to make the device better. For example, the original polygraph required 30 minutes of preparation to set it up for questioning. That was burdensome, and so was the use of the smoky paper which then had to be shellacked if the results were to be preserved. Keeler came up with a way that regular ink could be used so that shellacking was no longer necessary.
Keeler called the device he created the “Emotograph,” and he was the first American to receive a patent on what is commonly known as the polygraph—or lie detector device. He filed for the invention in 1925 and the patent was granted in early 1931. In the patent application, the device is referred to as the “apparatus for recording arterial blood pressure.”
Unfortunately, the Emotograph was destroyed in a fire, but Keeler reapplied himself and began creating a new machine. This time he was either employed by or received funding from Western Electro Mechanical Company. The company then successfully manufactured and sold the products to police departments around the country.
Keeler went on to found a polygraph school in Chicago, the Keeler Polygraph Institute (1948). In addition to running the school, he continued to work as a consultant in the field for the rest of his life.
Controversy Over Polygraph Results
Today polygraph machines employ computerized programs to help with the orchestration of the test as well as the evaluation of the results. But no matter how these machines are made or operated, there has been one consistent argument: Do they work or not?
The American Polygraph Association claims accuracy rates of over 90 percent but this is disputed by many scientists. A polygraph machine, in essence, records some type of emotional arousal. Critics point out that this can include fear and anxiety as well as a host of other thoughts and emotions.
In an article in Psychology Today (3-7-2013), it is noted that in 1998 the U.S. Supreme Court restricted the use of polygraphs in legal proceedings. In addition, most employers are now barred from using it as a technique to recruit honest employees.
Ironically, the one major employer who still relies on polygraph testing is the U.S. government. As of 2013, about 70,000 job applicants annually undergo polygraph testing by the federal government.
Critics also point out that there are numerous books and online courses that show people how to “beat the system,” making the test less useful if someone has read up on how to alter the results.
However, the American Polygraph Association still states that there are strong benefits to polygraph screening. The organization contends that job applicants are more honest in completing applications when polygraphing is part of the process. On a psychological level, this certainly makes sense. If a candidate thinks that he or she might get caught in a lie, then the person is far less likely to lie. That said, the critics have enough data behind them that it is difficult to accept the claim that the accuracy of the testing ranged between 86%-100%. (There are so many variables in environment and test-giver and composition of the questions that it is very difficult to understand how consistent results can be guaranteed.)
At this point, scientists would say that we do not yet have anything that can offer a 100 percent guarantee of human honesty, but one thing we know—inventors will keep trying.
Side Note: In articles about Thomas Jefferson, it is sometimes mentioned that he used a polygraph machine. During his lifetime, a polygraph machine was actually a letter-copying machine; Jefferson’s device saved him from having to re-write letters that needed to be sent out to multiple people. That alone was a remarkable invention for the time, but it is a different invention from the device that records heart rate or blood pressure.