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Can you really detect if someone is lying? The science behind lie detectors

Team StoryWeavers|November 25, 2020, 05:21 IST| 10

A bank robber. A detective. A confession. In most mysteries, this scene has us at the edge of our seats. Our mind racing with questions; all we want is the big reveal the story has been leading up to!

Can the detective pull out a confession? Will the robber reveal the truth? Did they catch the wrong person? The tension is palpable in the air at this point!

Image Source: Giphy

While this scene scores 10/10 for a dramatic flair, real-life detectives and police officers have to face this dilemma almost every day. In every case they handle, they have to determine if the person in front of them is honest. Their years of experience in the field certainly helps them find the truth, but there is also a handy device that comes to their aid – polygraph a.k.a the lie detector.

The Truth Of The Matter
The polygraph machine was invented in 1921, and is used to detect if a person is lying. The logic behind the device is that when people are lying there are some noticeable changes in their body. For example, increase in blood pressure, heavy breathing and sweaty palms. A polygraph measures these bodily changes. The person whose honesty needs to be put to the test is hooked up to the machine and asked a series of questions (this is called a polygraph test). Based on how their body responds while answering these questions, detectives decide if they are telling the truth or lying. Simple? Not quite.

The various parts of a polygraph help detect blood pressure, sweating and breathing Image Source: Wikimedia Commons

The Whole Truth
The use of polygraph tests is highly debatable as the logic behind them is not foolproof. Yes, there are some noticeable bodily changes when a person lies, but these changes also occur when someone is nervous. This might have happened to us in the past too. When we are questioned about mischief done by others, we still are anxious about answering it!

Being nervous while answering tough questions in common! Image Source: Giphy

Added to that, sometimes the questions in a polygraph test may not be adequately framed, or the person conducting the test may not carry it out well, making it difficult to assess if the results of the test are correct. So, if polygraphs cannot tell us a person’s honesty with complete accuracy, is there any point in using them? Yes!

Truth Finds A Way!
While the results of a polygraph test may not be entirely accurate, they do help detectives in choosing a path for further investigation. Under challenging circumstances, even a lead like that could help law enforcement professionals crack the case wide open!

Image Source: Giphy

Did you learn something new from this article? Let us know in the comments!

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Leave a Comment



Alokendra Mandal

November 29, 2020

Informative and interesting as well. I think one day this could also be possible to make this machine 100% accurate!!

Tanishka Raj

September 28, 2020

ya, if we prink ourselves then the polygraph machine can’t tell if we are lying??

Aparna Bhattacharjee

September 25, 2020

But I think if we prink ourselves then the polygraph machine can’t tell that we are lying ???


September 24, 2020

A man can control his own body while telling lies so it can not for all liers so improve it

Uday Raj khatri

September 24, 2020

Well I guess it is not 100% accurate if a person can control changes happening with his body during lying he can in one sense fool the lie detector test ??


September 23, 2020

Amazing ! These machines are just wow, Thank you Byju’s for these amazing fact about these gorgeous machines. ???

Anuj Sikarwar

September 23, 2020

Hey guys good evening to all I like this machine but I also want to know that how can we make this machine

Tulasi lasya

September 23, 2020

Ohh!! My god I had never seen this machine ..!!wow !!?

Neeraja Rajendra Paranjpe

September 22, 2020



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