Just how effective are lie detector tests?

Question

i have taken a lie detector test before and I failed. i was super nervous bc i was actually putting my life in the hands of a silly machine. i was close to hyperventillating and, of course, when your nervous your heart rate and your blood pressure goes up. they say all of these are signs of lying. i was being completely honest though. i was NOT lying but it said I was. so just how effective are these stupid machines?

Answer 1

put a thumb tack under your toe are take a Valium

Answer 2

The accuracy of polygraphs (the REAL name for "lie detector) all depends on the qualifications of the examiner. As you state, the machines measure heart rate, respiration, galvanic skin response (palm sweating), and blood pressure. The fact that you were nervous should not have interfered with the reading of the results. A competent examiner would have asked baseline (emotionally neutral) questions to establish YOUR personal baseline numbers. Any subsequent significant deviation of your readings from that personal baseline might indicate deception. If you were as nervous as you claim, I can't imagine ANY competent examiner being able to interpret scores as ALL your readings would have been "off the chart." Such test results should be deemed "inconclusive" not failure. Perhaps whoever you took the test for received an "inconclusive" and interpreted it as failure, but this is NOT accurate either.

Thus, the machines are 100% accurate in what they measure as they are measuring simple physiological responses. It is the INTERPRETATION by a human of those measurements that leads to potential inaccuracies.

BTW, as far as polygraph results being inadmissible as evidence in court -- this, as a blanket statement -- is simply NOT TRUE in the US. The Supreme Court has left it to the courts of each jurisdiction to determine how and when to allow it, or to exclude it altogether [United States v. Scheffer, 523 U.S. 303 (1998)]. They are frequently introduced as evidence in a case and they are weighed by the judge on their probative value to the case.

Answer 3

I took one when I tried to get on the police force

and

I BEAT IT

it exactly like George Costanza (Seinfeld) said."its not a lie, if you believe it"

Answer 4

I believe they are very effective.

Answer 5

Polygrapghs are very effective actually. The examiner knows you are nervous and therefore can "read between the lines" to know that a certain line went up because you were definitely nervous, but know by it's reaction afterwards if you did or didn't lie. They know how to read these things. Before you actually test, you are hooked up to the machine and the examiner studies the lines of your current state to see how nervous you are and if the lines are staying consistent with your nervousness. Once the first question comes, the examiner knows what pattern your lines should be in and if that changes, then it reads as a lie. Polygraph tests can take up to several hours depending on how long it takes the examiner to study your nervousness before you begin answering his questions. Now, you can certainly "out lie" the test if you know how. I've seen people do it.

BTW Melanie--- Polygraphs ARE admissable in the court of law, at least where I've been. They don't have a polygraph examiner on each case or whatnot, but if a lawyer hires one to question the person he is representing, and they receive the results, the lawyer has the choice to keep quiet [if the results would hurt the outcome for the client] or present the results in the next court hearing [if the results work on behalf of the client.]

Answer 6

Polygraphs are easy to beat you just have to be a bald -faced liar. The machine is calibrated by several test questions just panic when the test questions are asked and this establishes a base line of mild terror that will mask the physiological responses when you lie.

Answer 7

Lie detector tests are not admissible in a court of law. So there, you got your answer. No, it is not. Too easy to fake if you know how.

Answer 8

Carly is very affective. Not effective (note to the  questioner)

But  I am just waiting to hear from her now. she is  gorgeous.

Will

Answer 9

from what i heard they are right 96-97% of the time

Answer 10

Lie detectors can be beaten if you know how they work...you have to fool the machine during the base line phase...

The main value of the lie detector is the person tested assumes that the tester knows when he is lying and often comes clean on further questioning in an attempt to introduce mitigating circumstances into their testimony to lessen their sentence...