Over the years, police have devised a variety of innovative and clever ways to bring the bad guys to justice. Their tactics have changed significantly over the past few years, but some things have remained the same. The lie detector test has become a staple of modern police offices and it is utilized on a daily basis all around the world. It has proven to be an incredibly valuable tool and it has undeniably helped to put away thousands, if not millions, of bad people. What makes the lie detector test so beneficial and how have police been able to utilize it to their advantage? You’ll find out in the comprehensive and informative guide below.

What Is A Lie Detector?

First and foremost, you should familiarize yourself with the lie detector. This is a good chance that you’ve heard of these devices at some point or another. You’ve probably seen them on the big screen or on television. The lie detector does exactly what it sounds like it does. It is capable of determining whether or not a person is being deceptive. While the machine is not entirely accurate, it can still prove to be beneficial for modern law enforcement agencies.

The polygraph is the most common type of lie detector test utilized by modern law enforcement. These machines attempt to determine whether or not someone is lying based on various physical parameters. This will be explored in greater depth below.

How The Polygraph Works

When a detective places someone into a chair and straps them to a polygraph machine, they’re interested in measuring several physiological indices. They’ll want to analyze the individual’s blood pressure, respiration, skin conductivity and pulse. These statistics are measured when the suspect is questioned by the officer. The impact of the question on the suspect’s physiological nature can help to determine whether or not they’re telling the truth or they’re being deceptive at that point in time.

Understanding The Types Of Lie Detectors

All lie detector tests are administered in the same manner. This usually involves a specialist attaching a cuff to an individual’s arm, which will read the blood pressure, and two more small devices are placed on the tips of the fingers. These smaller devices are geared towards reading perspiration activity. Sometimes there can even be straps placed around the individual’s stomach to monitor and measure breathing patterns. Although, tests are administered in a similar manner, you need to be aware of the fact that there are several different types of polygraph tests available.

Conventional Testing Methods

Conventional tests are also sometimes referred to as analog instruments. While they are going out of style, professionals around the world sometimes still utilize them. These devices usually are composed of analog dials, switches, a roll of chart paper, and moving pens that record results. The examiner has to be specially trained in interrupting the results of the chart on each question that he or she asks.

Invented By A Police Officer

As you probably already guessed, the polygraph was invented by a police officer. It was originally introduced to the public in 1921. The machine was developed by John Augustus Larson and a police officer with the Berkeley Police Department in California. The polygraph managed to make the Encyclopedia Britannica’s 2003 list of the world’s greatest inventions. Today, the overall efficacy of the polygraph remains hotly debated by the scientific community. Nevertheless, it remains a very effective tool for modern detectives.

Even if the machine isn’t entire accurate, police have found a way to use it to put pressure on suspects. This can help them get to the truth of the matter much easier than they would without any aids.

Can Polygraphs Be Defeated?

When police come up with schemes to ensnare criminals, you can guarantee that criminals will attempt to conjured ways to allude capture. They’ve done the same with polygraph tests. Over the years, criminals and military regimens all around the world have attempted to devise ways to overcome lie detectors. There are two main countermeasures that are commonly utilized to throw off the machine and make it less reliable. Some criminals will attempt to alter their psychological and physiological state to throw off the machine’s readings. It is also possible to use a technique referred to as Specific Point.

With Specific Point, the individual in question will change their physiological and psychological state at specific points during the examination. This will allow them to throw the machine for a loop and make the reading unreliable.

Most Criminals Cannot Defeat Lie Detectors

The truth of the matter is that most basic criminals are unable to defeat lie detectors. It can take many years of training and experience to learn how to control one’s respiration, pulse and heart rate. Therefore, most criminals will be unable to escape justice, after they’ve been strapped to a polygraph machine. Soldiers will often undergo specific training for this purpose. However, modern criminals will not. Therefore, detectives and police officers almost always have the upper hand over the suspect in this regard.

Can Police Officers Really Rely On Lie Detectors?

There is a major debate as to whether or not police can depend on lie detector tests. The truth of the matter is that lie detectors are not 100% accurate. Nevertheless, it has been proven time and again that they can be enormously beneficial. It is absolutely essential to remember that lie detector test results are not admissible in a court of law. Therefore, they’re not considered to be credible evidence. Still, this doesn’t mean that the machines cannot be helpful. Most ordinary individuals strongly believe that lie detectors are completely truthful and reliable.

This makes it possible for police officers to use the machines and their results as leverage to attempt to obtain a confession from a potential murderer or thief. So, there is a good chance that detectives cannot always rely on the result. Nevertheless, they can still find ways to put these machines to their advantage.

The Ted Bundy’s Of The World

When it comes down to it, lie detector tests cannot be completely accurate. It doesn’t take scientific evidence to figure this out. One just needs to go back into history to find the evidence. First and foremost, you should take a look at the notorious serial killer, Ted Bundy. The man was accused of killing 18 women. He was ultimately convicted at time and put to death years later. Surprisingly, it has been said that Bundy was actually able to pass every conventional lie detector test thrown his way.

With that being said, it is undeniably true that some people may be able to throw off lie detectors naturally. Some people may just be born with the instinct to overcome these tests without any additional training. Still, it is true that most people will not be able to do so. And even then, Bundy was ultimately brought to justice. Therefore, the lie detector should not be considered a miracle solution for modern police. Instead, it should be just another tool in their massive toolbox.

The Curious Case Of Melvin Foster

In another surprising case, a man named Melvin Foster failed a polygraph test after being accused of murdering multiple women. It was later determined that another man was responsible for the crimes. Melvin Foster was given a polygraph test in September of 1982 in connection with the investigation into the Green River Killer. At the time, Foster failed his test. At the same time, the real murderer, Gary Leon Ridgway, passed his polygraph test. Many years in the future, Ridgway would be captured thanks to DNA.

Nevertheless, this is yet more proof that police and detectives cannot rely 100% on lie detectors. By utilizing lie detectors in conjunction with other techniques, people will ultimately have a better chance of bringing criminals to justice. However, they should never rely entirely on the lie detector, because it could potentially lead them astray.

How Accurate Are Lie Detectors?

So, how accurate are lie detectors? The truth of the matter is that there is no universal answer. It truly depends on a handful of different factors, including the suspect in question. Experts believe that the accuracy will depend largely on the suspect. For some people, the machine might deliver 90% accuracy. However, for others, the accuracy can drop as low as 70%. It is also important to remember that the machine’s administrator and the one reading the results need to be thoroughly trained and certified.

It takes the perfect combination to ensure that the polygraph and other lie detectors are as reliable as humanly possible.

Medications That Affect The Results

Most examiners will ask the suspect if they are currently taking any type of medications, before they perform the test. The reason for this is because some drugs can alter the test’s measure responses. Antihypertensive medications are just one example. These medications are designed to lower blood pressure levels and are prescribed to people with hypertension. Since lie detector tests measure blood pressure, the results could be altered if the individual is taking an antihypertensive drug, which will keep the level to a minimum.

Antianxiety medications are also highly known for altering lie detector test’s responses. These medications provide a calming and relaxing state in individuals who have been diagnosed with anxiety. Antianxiety medications, such as Xanax, Ativan and Valium alter emotional responses to everyday situations. So, if the suspect is taking a regimen of antianxiety medications, it will do no good trying to test them.

Police Still Use Lie Detectors

Police understand that lie detectors may be faulty to some degree. Nevertheless, they are still adamant about using them. In fact, it is said that the Federal Bureau of Investigation conducts a polygraph test on everyone that is interviewed for a job. The DEA, CIA and other agencies do the same. And of course, local and state police utilize polygraphs as well. They’re often used to determine whether or not a suspect is lying, to help aid an investigation and even to monitor sex offenders. So, why are polygraphs still used?

It is believed that they’re very popular, because they serve as a good prop. It is believed that the lie detector can be a great part of the theater of the interrogation room. They can help to scare the suspect and convince them that they’re able to slip up and tell the truth. In return, this may encourage them to tell the truth and give up a confession. On the other hand, it is believed that repeated lie detector tests can help keep some people on the straight and narrow.

This is why many districts have decided to use lie detectors to keep track of sex offenders. By forcing them to take a test of regularly, they’ll feel obligated to remain safe and clean. Whether or not this is actually effective remains to be seen.

Police Use For Manipulation

The presence of the lie detector test may prove to be more beneficial than the test itself. When the lie detector enters the picture, the suspect will immediately believe that they’re going to be found out. They’ll believe that the machine is going to know for sure whether or not they’re lying. At the same time, detectives can often use the test to manipulate the suspect. By running a test and telling the suspect that they’ve failed, there is a good chance that the detective may be able to convince the suspect to give up some crucial information.

While this activity might not be moral, detectives must do whatever possible to take criminals off of the streets.

Putting The Suspect On The Hot Seat

Another thing to remember is that the polygraph can be used to put the suspect on the hot seat. Sitting in an interrogation room is one thing. Being hooked up to a polygraph is another. Once you’ve been hooked to a polygraph machine, you can pretty much guarantee that you’re going to be nervous. If you’re guilty of anything whatsoever, there is a good chance that the machine’s presence will make you eager to squeal and tell the truth. Sometimes, the machine doesn’t even need to be turned on to make it effective.


At the end of the day, lie detectors are definitely not flawless. Nevertheless, they’ve proven to be a viable aid for modern law enforcement. By using these machines, police will ultimately be able to gain crucial details that can help them solve the crime. Of course, there is a fine line here. Police need to use the machines strategically and cautiously to ensure that innocent people are not harmed in the process.