The Science Behind Polygraph Examinations: Do They Work?

Behind Polygraph Examinations

American Polygraph Association claims that polygraph examinations are 90% accurate. However, critics have a different say in it. Everyone would want to find a way to know when someone is lying. It was considered a significant breakthrough for law.

Behind Polygraph Examinations

No method is accurate to prove if someone is lying as it determines the same using cardiovascular, respiratory, and electrodermal activities. Therefore, polygraph machines could be deceptive, and many criminals can get scot-free.

We shall see in this blog whether lie-detecting tests are viable or if one should look for some other method. But, first, let’s learn the science behind this test:

The Science Behind Polygraph Examinations:  

We shall now discuss the three physiological response activities to assess the lie detector tests:

  • Cardiovascular
  • Respiratory
  • Electro dermal

Cardiovascular Response: 

Many cardiovascular activities can impact the responses linked with lying. It includes your heart rate, blood pressure, and other processes, like fight or flight response.

For instance, polygraph examiner OKC determines the same by attaching complete arm and handcuffs with a sphygmomanometer. This is what you must have seen used by doctors.

Furthermore, it also includes photoelectric plethysmographs, which send infrared rays through the tissue to evaluate the answers. Photosensors then assess the rays reflecting or passing through the same. You can check the blood volume without the need for any additional equipment.

Respiratory Response: 

There are many different signs that someone may be lying, but one of the most obvious is their breathing. Breathing rates can change depending on what they think and how you feel about it. So, it makes this an excellent indicator of whether or not someone could deceive.

A respiratory function test is typically used to assess how well a person can breathe. The device includes pneumatic rubber bellows around the subject’s thorax and abdomen, which expand during inhalation or exhalation.

Furthermore, this motion prompts changes in the circumference of these areas as measured by encircled calipers on either side. Breathing creates pressure inside your body because air needs space to move through and exert force against muscles.

READ MORE: Oklahoma Judicial Process Servers

Electrodermal Response: 

Electrodermal activity is the most accurate and reliable way to measure stress. Why? The skin’s electrical resistance makes it a great indicator of human emotional well-being. It largely depends on eccrine glands for sweat production, and the sympathetic nervous system regulates it.

Furthermore, electrodermal activity measures the subject’s skin conductance level and any changes to it, as well as their spontaneous responses. These are recorded by two electrodes attached to your palm or fingers, which administer current through them at different frequencies.

Is Polygraph Examination Effective? 

To determine the precision and potential of screening and other investigative tools. This test is a viable source for extracting security issues and other criminal investigations. In addition, it is vital to learn that evidence must support such results.

You can also opt for investigative methods to decrease the rate of deception. It includes interrogation, where professional investigators and observers assess the accused. This test requires evaluating the marginal benefits and adverse outcomes to reach an accurate point.

It was seen that about two and half a million polygraph examinations are carried out in America every year. Between 2002 to 2005, the Federal Bureau of Investigations (FBI) calculated a $24.9 million budget for this test.

The Deception in Polygraph Examinations


In law enforcement and criminal justice, there is a new wave of questioning techniques that are more psychological than physical. With these types of interrogators specializing in micro-expressions or nonverbal cues, it seems like chance would be an impossible source for detecting lies.

Several OJPS claim the polygraph not only tracks its subject’s physiological responses in real-time but also records a graph with three values agreeing to cardiovascular, respiratory and electrodermal results.

However, is it possible that these amounts of data are useful when determining if someone’s telling the truth?

Moreover, the accuracy of a polygraph test can be compromised. This is because it relies on individuals’ physiological responses to differing between each other or even the same person under different circumstances.

In addition, complicating matters is that changes in breathing rate and galvanic skin response will affect how someone answers questions regarding guilt/innocence regardless of their actual status.

The practice of mindfulness and breathing techniques can help people have some control over their physiological responses. For example, they may use this to reduce stress or worry more easily than before.

Polygraph examination OKC or any other state is unreliable, often resulting in false positives and negatives. However, a study found that accuracy rates average at 54%. If that does not satisfy you, you can contact Keefe Private Investigations (KPI) to thoroughly inspect the case.

Building Improved Polygraph Examination Devices: 

Blood pressure testing devices are an integral part of the medical field and can detect lying. Therefore, your doctor must use them whenever you pay him/her a visit.

Piezoresistive sensors are commonly used MEMS devices that measure electrical resistance changes. It relies on how much force there was before and after to calculate your reading upon pressure.

Moreover, the blood pressure monitoring device must monitor the patient’s vital signs with accuracy while also being safe for them. To do this, designers need information on how these devices operate and what they might encounter in use before releasing them onto markets.

The Uncertainties About Lie Detectors: 

Polygraphs can be pretty controversial. The main argument against them is that stress is not just manifested when someone lies. It could also happen because of the following reasons:

  • Fear
  • Embarrassment
  • Pain from being strapped down
  • Inquiry in such an uncomfortable

Moreover, polygraphists themselves are vulnerable, too, as some even experience bias during their work. Due to what someone educates them beforehand about how they should react under pressure, which then labels innocent subjects guilty before anything happens.

The Alternative Option: 

In a world where people are always looking for ways to avoid the truth, there is now an eye-scanning technology that can help detect liars. It works by measuring pupil dilation and movement in response to specific questions or statements.

The future of lie detection just became more accurate with the Eye Detect system. This eye-catching software can detect when someone is lying to you, and it does so with an accuracy level comparable to that found in modern-day polygraph tests.

The Final Thought: 

When you lie, your heart rate speeds up, making breathing more difficult. The polygraph machine can detect these changes by looking for signs like increased blood pressure or sweating out on the surface of our skin.

When considering the currently available polygraph examinations in Oklahoma, it is evident that most studies agree with using current procedures is not scientifically reliable.

Therefore, the widespread utilization of pre-screening tests such as CQT cannot justifiably be used in decision-making processes. Because they lack validity and accuracy when applied without further research into alternative methods which would provide more accurate information about an individual’s guilt or innocence.


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