how does a lie detector work

You may have seen it at a party, in a movie, or on TV. That person hooked up to the machine, with wires running from their fingers, asking questions like “Have you ever cheated on your taxes?” or “Did you ever cheated on your partner?” That person is taking a lie detector test, also called a polygraph.

In private investigation, a lie detector machine can be used to gather information from a person of interest in order to determine if they are lying about a certain matter.

If you are suspecting your spouse of cheating, for example, you can hire a private investigator to administer a polygraph test to see if they are telling the truth. So, how does this machine work? Is it accurate? Can it be used in a private investigation? Let’s take a look.

What is a polygraph (lie detector)?

Polygraph or so called lie detector is an actual instrument that is used to record and measure several physiological indices such as skin conductivity, respiration, and heart rate while the person is asked and answers a series of questions.

The basic principle behind the working of a polygraph machine is that when a person lies, they experience stress and anxiety, which causes an increase in the aforementioned physiological indices.  The machine records these changes and produces a graph, which is then interpreted by a polygraph examiner to determine if the person is lying or not.

How does a lie detector work?

woman tested for infidelity

When a person is asked a question, their brain will automatically process the answer and send out signals to different parts of the body.

These signals can be measured by changes in things like heart rate, perspiration, and respiration. The polygraph machine records these changes in order to determine if a person is telling the truth or not.

A polygraph examiner will also take into account other factors, such as body language and the tone of voice, in order to make a determination.

The accuracy of a polygraph machine depends on the skill of the examiner and the question asked.

For example, if a question is too vague, it may be difficult to determine if the person is lying or not.

Can a polygraph be used in a private investigation?

Yes, a polygraph machine can be used in a private investigation in order to gather information from a person of interest.

A private investigator may administer a polygraph test to a person who is suspected of cheating, for example, in order to determine if they are telling the truth.

The accuracy of the test will depend on the question asked and the skill of the examiner.

Accuracy of polygraphs

Private investigator analyzing polygraph results

The accuracy of a polygraph test depends on the question asked and the skill of the examiner.

A well-trained examiner can usually achieve an accuracy rate of about 80% to 90% when administering a polygraph test. 

This means that 8 out of 10 times, the machine will be able to correctly determine if a person is telling the truth or not. However, research suggests that it works best at 55% at some time.

Although polygraphs are not 100% accurate, however, and there is always a margin of error.

The accuracy of a polygraph test can also be affected by things like anxiety, medication, and alcohol.

If you are considering taking a polygraph test, it is important to discuss any concerns you may have with the examiner beforehand.

Is a lie detector test worth it?

A polygraph test is not always accurate, but it can be a helpful tool in a private investigation.

If you are considering taking a polygraph test, it is important to discuss any concerns you may have with the examiner beforehand. It may also be helpful to consult with an experienced private investigator to see if a polygraph test is right for your situation.

Get expert help from Triumph Australia

Whether you’re trying to catch a cheating spouse or you need help with another private investigation, Triumph Australia can help.

Our team of experienced and licensed private investigators will work with you to tailor a solution that meets your needs. Stop wondering and get the answers you need today. Contact Triumph Australia to learn more.

Call us at 1300 147 909 or fill out our contact form and we’ll have one of our private investigators get in touch with you.

With an excellent team of Elite Investigators with many years of experience, we definitely have the know how to bring you the results that you are seeking

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