Who Invented The Lie Detector (polygraph)?

The lie detector (polygraph) seems like something out of a detective movie! Just think: how an accurate machine that can tell if someone is lying by checking certain physiological signals like their heartbeat or sweat production could change lives! In this article, we’re exploring questions like what is a polygraph, who first imagined this intriguing invention, its cost, and its path of development into modern day lie detector devices. So grab your detective hat – we’re about to uncover this mysterious invention!


Here are the historic figures who invented the polygraph:

John Augustus Larson

John Augustus Larson was a clever police officer from California who saw a way to make solving crimes easier using science. In 1921, while he was still a medical student, Larson built the first polygraph that looks a bit like the lie detectors we know today. His lie detector worked by measuring not just one but several body reactions at once—like heart rate and breathing. Larson’s invention was so good at finding out if someone was lying that it quickly became a tool police officers wanted to use. He even worked on making his polygraph better by adding a way to interview people, which helped him figure out the truth more effectively.


James Mackenzie

Before the lie detector became an instrument for uncovering lies, its origins can be found in Scotland with James Mackenzie, a doctor. At the turn of the 20th century, Mackenzie developed a simpler version of polygraph to monitor heartbeats using rubber cups called tambours that were placed around the neck and wrist to pick up pulse waves that were drawn as lines on paper as an aid to seeing if anything was amiss with one’s heartbeats – his work proved groundbreaking while unknowingly setting the foundations for modern lie detectors!

William Moulton Marston

Marston also made significant strides toward shaping lie detector history – in the early 1920s, he devised an instrument which measured blood pressure changes as an attempt to determine whether someone was lying. His research led him to conclude that when people lie due to nervousness, their blood pressure increases, which is another key indicator. While Marston didn’t invent polygraph machines like what we use today, his ideas had an influence on their development and later use.

Further Developments

After John Augustus Larson and William Moulton Marston made their mark on the polygraph world, more inventors stepped in to tweak and improve the machine. One of the standout contributors was Leonard Keeler, who worked closely with Larson. Keeler was fascinated by the polygraph and wanted to make it even better. In 1925, just a few years after Larson introduced his version, Keeler upgraded the polygraph by adding ink pens that recorded the measurements more clearly, making it easier for examiners to see the results.

Keeler didn’t stop there. In 1938, he added another important feature: the psycho galvanometer, which measured how much a person sweats during questioning. Sweat can increase when a person is nervous, which might indicate they are not telling the truth. This made the polygraph more effective and turned it into the kind of lie detector we recognise today.

Thanks to these improvements and others that followed, the polygraph became a valuable tool not only for law enforcement but also for other uses, like verifying the truth in various scenarios outside the police station. Keeler’s work helped establish the modern polygraph as a complex instrument that measures multiple signs of stress to indicate whether someone might be lying.

History of Lie Detector, Methodology and Current Status

Early 1890s

In the 1890s, attempts to develop a machine capable of detecting lies first began to take shape. Scientists and inventors were intrigued by the notion that our bodies might give away when we lie; during this period, there was much curiosity as people explored human psychology and physiology more closely.

Cesare Lombroso was an Italian criminologist and innovator during this era. He pioneered experiments using devices that measured changes in one’s body to detect dishonesty. Lombroso’s field-breaking work involved using blood pressure and pulse rate measurements when answering questions to detect dishonesty, as it introduced the notion that physical signs like faster heartbeats could indicate lying.

While these early methods weren’t perfect, and the machines were quite basic, they laid the groundwork for more sophisticated technologies. The efforts in the 1890s led to an innovation surge that eventually resulted in the modern polygraph. This period proved that scientific methods could indeed reveal hidden truths within us all.

1921 to 1930s

Significant advancements were made in lie detection between 1921 and the 1930s. In 1921, John Augustus Larson, a brilliant medical student and California police officer crafted what many consider the first modern polygraph. This device was a breakthrough because it could measure several body responses simultaneously—like heart rate, blood pressure, and breathing—while questions were posed to the subject.

William Moulton Marston, a psychologist and lawyer, conducted studies investigating how blood pressure fluctuates with dishonesty; these investigations enormously affected current polygraph methodologies.

Leonard Keeler made significant advancements to Larson’s original polygraph design during the late 1920s and early 1930s by adding features that improved the instrument’s reliability and usability. Keeler played an essential part in popularising it further by showing its effectiveness in criminal cases and courtroom settings, leading to greater acceptance.

Beginning in the 1920s and continuing through to the 1930s were crucial steps toward making polygraphs an indispensable tool in criminal justice, laying the groundwork for further refinements in later decades.

Mid-20th Century:

Mid-20th-century improvements to the polygraph (lie detector) marked an expansion in its use and improvement accuracy of lie detector tests. New techniques were created, and improvements were made to the design, making polygraphs more accurate than ever.

John E. Reid was an important figure during this era; in the late 1940s, he developed the Control Question Technique (CQT). This method distinguished truthful answers from those that might mislead by comparing physiological responses to unrelated control questions with those related to an investigation – becoming very popular and still utilised today as part of polygraph tests.

The mid-20th century saw the polygraph become increasingly mainstream across various fields beyond law enforcement, including government and business, for security screenings and employment verification purposes. Alongside this increase came debates regarding polygraph’s accuracy and ethics that continue today.

Overall, this period cemented the polygraph’s place as an effective yet sometimes controversial method of unearthing truth. Its development during this era laid the groundwork for how it’s utilised and perceived in modern-day investigations.


The year 1997 brought some fascinating changes and ongoing debates over polygraph testing’s reliability and ethical usage. While no major advancements in technology were seen this year, it marked a change in how people discussed and used the technology.

At this time, polygraph tests remained a popular tool among law enforcement agencies for investigations, as well as government agencies, to screen employees for security purposes. Yet there was heated discussion regarding their accuracy and fairness; experts noted that while polygraph tests could be helpful in uncovering criminal acts, it wasn’t foolproof and could sometimes give false results.

Discussions held in 1997 highlighted the need for ongoing research and development to enhance polygraph performance. People began to recognise more than ever before that while polygraph could be an invaluable asset, its usage must be approached carefully with an awareness of its limitations.

This year saw a significant increase in public understanding about how polygraphs operate and when and why they should or shouldn’t be relied upon, leading to more informed discussions around polygraphs that take into account both potential benefits and challenges they present.

Current Status

Today, polygraph testing (more commonly known as a lie detector) remains widely discussed and used, though not without controversy. Courts typically don’t rely on lie detector tests solely as evidence because its accuracy varies; however, many police departments and government offices still utilise polygraph tests during security checks or investigations to detect whether someone might be lying.

Due to advances in technology, modern polygraphs are far more advanced than their predecessors. They can now monitor several vital signs simultaneously–from how fast your heart beats to your blood pressure and respiration rates as well as sweat production. However, these updates have made polygraphs more reliable, but not perfect; there are still places where they can go wrong, and sometimes, people intentionally try to beat the lie detector test and succeed.

People usually dispute whether it’s right to use polygraph tests because sometimes the machine can get it wrong, falsely accusing someone of lying when they were actually telling the truth or failing to detect an offence altogether. That is why scientists continue working on improving its capabilities while exploring other technologies which might replace it altogether.

While polygraph examination can still be an invaluable asset in certain circumstances, its efficiency and ethics are constantly under review by professionals in this field.

What is Polygraph Test: Lie Detector (Polygraph) Methodologies:

Polygraphs or lie detector tests utilise two key methods for assessing whether someone might be lying. They involve measuring various bodily reactions that indicate stress or nervousness that could suggest they’re not telling the truth.

Comparative Question Test (CQT):

A CQT is a popular form of examination wherein someone being tested is given three types of questions–irrelevant, relevant, and control. Irrelevant ones shouldn’t cause stress (for example, asking your name); relevant ones focus directly on what’s being investigated (such as asking whether money has been stolen), while control questions serve more to create reactions with generalised wrongdoing (like “Have you ever stolen anything?). The idea is that truthful people will react more to the control questions than to the relevant ones, while those who are lying will react more to the relevant questions.

Concealed Information Test (CIT):

Also referred to as the Guilty Knowledge Test, this method is employed when an investigator suspects someone of knowing specific details about a crime that only criminals would understand. The test involves multiple-choice questions with one correct answer and several decoys; if a significant physiological response occurs when correct answers appear on multiple-choice exams, this may indicate knowledge about this crime.

When Was The Lie Detector Used For The First Time In Court?

The first appearance in court was in 1923 during a trial involving William Moulton Marston, who was not only a lawyer and psychologist but also the inventor of an early form of polygraph technology.

Marston employed his device in Frye v. United States, where he attempted to defend a young man charged with theft. Marston attempted to use results from his lie detector test as evidence that showed that the accused was telling the truth, however the court was dubious about such technology and decided that its polygraph results weren’t reliable enough for court use as evidence – this decision set up what is known as the Frye Standard which requires scientific evidence be accepted by an expert community before being admissible as court evidence.

Though first introduced into court in 1923, polygraph technology wasn’t immediately accepted by everyone. Debates ensued regarding whether this technology should be trusted as part of legal proceedings, showing just how new inventions such as polygraphs require time before being fully accepted by everyone involved.

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