Lie detector

[SurreyGuy]

Not that any of the following applies to me, but I was just wondering.......................

Imagine someone went out and got roaring drunk and committed a crime, but due to be so "out of it" couldn't remember what they did.

If they then took a lie detector and (due to my memory loss) answered "no" to the question "did you commit a crime when you were drunk?", would the lie detector know they was lying? I say "lying", but in essence, they would be amnswering "no" coz they genuinely believed that they had not committed a crime.

If the lie detector WOULD "know", how does it do that?

T.I.A.

[Houdi]

Lie detectors rely on the responses of the subject and the interpretation of the tester. Impared memory, the subject's perception and mental/physical illness are just some of the reasons why lie detector tests aren't nearly as reliable as the like of Jeremy Kyle would have us believe.

[alexprior]

Polygraphs don't detect lies, merely the slight changes in a person's pulse etc when anserwing certain questions. The detection of 'lies' is down to the operator who must be skilled in using the machine and also setting up the equipment and the subject with a whole battery of tuning questions to gauge the subject's responses to known answers.

If the subject could not remember the incident, then their answer of 'no' would be genuine as far as they were concerned and the polygraph operator would mark their response as an accurate one.

Further to the last answer, no, they are not accurate and are not permissable as evidence in UK courts because of this.

[SurreyGuy]

Thanks folks