How lie detectors work

Some pointless travia for all you swats. I actuall found this rather intresting.

On many talk shows and reality television programmes lie detectors are often implemented. I quote one of these talk show hosts by saying "lie detectors are 98% effective". Thinking that was impressive, i was wondering why they dont use lie detectors in law and court, given such a high success rate.

Saying a lie detector works to only 2% error, is quite a bold statement given how snubbed and mistrusted it is within society, yet can a jury, which has to account for human error, really be anywhere near as effective? Pahaps not....pahaps so, but i was really thinking upon the basis of thier success, they should at least be tested.

But i got to wondering, just how do lie detectors work?

Ok first of all, lie detectors cannot detect lies, is impossible to manufacture a device that can be so specific in interpretating a signal or a reaction by the brain, that can immediately define the difference between reality and fabrication. Currently our science is no where near that advanced.

However what happens when somebody answers a question, is that the lie detector measures a response in the brain. This response alone means nothing, its useless, in fact you could continue asking questions in this manner for an eternity, and so long as the answer was unknown by the person asking, you would make no progress whatsoever. The signals given could all be different, or all the same, yet having no basis for comparision means truth or lie is unobtainable.

In order to find out when a person is lieing, they must first find out when they are telling the truth. So the asker would have to already know some of the answers, before he starts asking the questions. Now provided the answers are given in some certainty, it wouldnt matter what questions were asked, the brain signal given by the person in question when answering the truth, would always be consistant.

So what you would get when the truth is told, would be a signal in which you could base as "the truth".

Then you ask the unknown questions, what would happen. Well as you may have guessed the signal changes. If the person starting telling lies, the signals in brain would fluctuate, or even loose correlation altogther, at this point the person asking the questions can confirm some uncertainty or even outright fiction, is being given by the person in question.

Maybe some of u knew this, maybe u didnt, but that was something i actually found quite intresting and it has a excellent exclaimation point.

The irony is: Its telling the truth, that unveils your lies.

Hmm I always thought it just measured your heartbeat and any changes.

thats pretty awesome


i thought the same thing about em when i watched an episode of Mythbusters having to do with a myth if u can beat them.

how bored are you pheo?

I thought it measured Heartrate and pulse......

Heart rate and pulse are the same things bdl, lol.

Grimlore wrote:

thats pretty awesome


i thought the same thing about em when i watched an episode of Mythbusters having to do with a myth if u can beat them.

It is possible beating a lie detector there was a man from USA somewhere, there could cheat it, and he was just a ordinary man. The most ironic in it was that he was a salesman, i found that quite funny myself. A salesman there can cheat a lie detector that sure are a dangerous combination lol.

But ya i agree phoe i also wondered that a lot of times why they aint using it in courts? When it got such a big success rater it's kinda disturbing they never use such stuff. When they actually got the machines to prove if people are lieing or not.