How accurate are lie detector tests?

I've heard that they are as low as 80% accurate, but I think that is a low figure from a source that doesn't like lie detectors. From what I have heard, the point to a lie detector isn't usually to confirm the truth or prove someone was lying. Knowing that lies may not work will often cause people to make more accurate testimony, and make the times they are lying more obvious. In addition, the interviewer doesn't need to personally insult the person who is being interrogated--he can question the truth of a statement and blame it on the machine, so the person interrogated won't change the subject by insulting the interviewer--he'll be forced to either repeat the 'lie' or come up with a new one. It's more a tool to extract a confession than one to confirm or dispute one.

They're not very accurate, people who operate them claim they're 99% accurate, but if that was really the case they'd be legal in court. Taken from wiki - link below: Numerous studies of polygraph validity have achieved rates of 80-95% for the kinds of tests used with specific issues, such as allegations in criminal cases. Drs. Heinz and Susanne Offe reported 93% accuracy in 2007 when using conventional field methods.[21] In a 2008 article Drs. Frank Horvath and John Palmatier reported accuracy as high as 91%.[22] Validity of polygraph remains controversial.[23][24] Despite claims of 90% - 95% reliability, critics charge that rather than a "test", the method amounts to an inherently unstandardizable interrogation technique whose accuracy cannot be established. A 1997 survey of 421 psychologists estimated the test's average accuracy at about 61%, a little better than chance.[25] Critics also argue that even given high estimates of the polygraph's accuracy a significant number of subjects (e.g. 10% given a 90% accuracy) will appear to be lying, and would unfairly suffer the consequences of "failing" the polygraph.

With a traditional polygraph, any question that goes into emotional minefields is not likely to produce a verifiable result. The police and the courts may use them to eliminate suspects, but they are inadmissable in court because they can be beaten. There are more modern, less-intrusive lie detection methods based on voice stress levels and other biometrics, but strangely enough - or maybe not, when you think about it - politicians oppose these tests being accepted.

The lie detector test measures fluctuations in certain bodily functions. These are: blood pressure pulse respiration breathing rhythms body temperature galvanic skin response (sweating) Now, when we lie it is highly likely that all these will increase. However, when I do anything that provokes an emotional reaction they all go up. I've had a polygraph test performed on me and seen how I was been able to manipulate the results with a little bit of thought and practice. As one of the above posters said - if it were actually reliable it would be used in a court of law.

97%, thats what they say on Jeremy Kyle!! Police can't use them because they are not fully effective and it would never stand up in court! Im not sure about the violence in a realtionship but some people can trick them!! Hope i helped hunn xx =]

They are 98% accurate, any violence in a relationship has no different affect on them at all, a lie is lie! Simples!

95% has to be 99.9% for use in law