Why don't they use Lie Detectors on ALL criminals?

[VBboy]

Why even bother with the trial, lawers, etc?
Why not just give the potential criminal a lie detector test to find out with a medical degree of certainty if he or she is guilty?

Example: we are trying to find out of X has murdered Y. Why look for the murder weapon, ask about the alibi, etc? Hook the person up to a polygraph and find out in a matter of minutes if he is guilty or not. Right?..

 

[notfred]

Because lie detectors aren't all that accurate. That's why they can't use them as evidence in court.

 

[VBboy]

Originally posted by: notfred
Because lie detectors aren't all that accurate. That's why they can't use them as evidence in court.

I thought they were extremely accurate, unless the subject has received special training... But then:

#1: Studies offer a mixed picture. In 1996 the Journal of General Psychology looked at 41 criminal cases and found that control-question tests were 93-96% accurate. Tests where some study participant pretended to steal $5-20 have produced similar findings.

#2: A 1997 survey of 421 psychologists estimated the test's average validity at about 61%, a little better than chance. And University of Utah psychologists published a 1994 report that suggested biting your tongue, pressing your toes to the floor and counting backwards by 7's during control questions would screw up the accuracy of polygraphs.

Interesting

 

[no0b]

Originally posted by: notfred
Because lie detectors aren't all that accurate. That's why they can't use them as evidence in court.

They are also easily defeated, You need to see a Popular Science Magazine about lie detectors then their next one with a guy from prison wrote how the article was full of bullsh!t and how to evade the detectors.

 

[NakaNaka]

Originally posted by: notfred
Because lie detectors aren't all that accurate. That's why they can't use them as evidence in court.

Bing Bing Bing.

 

[LH]

Because, because people can beat them with a small amount of training, and they can say an innocent person is lying.

 

[tcsenter]

Why even bother with the trial, lawers, etc? Why not just give the potential criminal a lie detector test to find out with a medical degree of certainty if he or she is guilty?

"Medical degree of certainty"? lol! Where did you come up with that phrase?

We don't use them because they did not exist when the constitution was written. There is no 'push' to amend the constitution and replace right to trial with a lie detector test because the ability to predict or detect truthfulness or deception ranges from simple chance to 96%, depending upon a number of difficult to control factors. Truthfulness and deception are not necessarily measures or indicators of guilt or innocence of the crime in question.

Polygraphs ARE used frequently in investigations, as an investigational tool the polygraph carries much more merit.

 

[fatbaby]

well a person could be extremely nervous and yield inaccurate results or the person could have a thumbtack in his sock which would distract him, therefore yielding inaccurate results, aka false positives

 

[Jmman]

They are not even close to reliable, medically or other wise......

 

[fr]

Tests where some study participant pretended to steal $5-20 have produced similar findings.

?

 

[BeauJangles]

Originally posted by: Jmman
They are not even close to reliable, medically or other wise......