lie detecter tests

[veritysims]

to my shame, i watched trisha on itv the other day and they had lie detecter tests on partners suspected of cheating. all good stuff, but, trisha (fountain of knowledge) claimed that the tests are 98% accurate. if this is the case why are they not used in court to prove the guilt of defendants who will not admit to their crimes? cheaper  and probably more accurate than funding juries. 

[archbishop]

98% is not good enough. If there is any doubt (2%) then you cannot convict.

[Samantha0]

I watch Trisha too, and I too have wondered about this!

What also got me was the fact that Trisha wouldn't give lie detector tests to couples who have violence in their relationship....Maybe because violent people don't deserve it? I don't know.

[bernardo]

(1) The claim of 98% accuracy is probably grossly exaggerated.

(2) 98% is not certain enough to justify a conviction.

 

"Lie detector tests" do not detect lies; they measure and detect variations in skin temperature, conductivity, heart-rate, sweat and so on.  In other words, they measure the physical things which tend to happen to the body when someone lies.

It is possible for someone who is an experienced criminal to train him/herself to lie without giving it away;

similarly it is likely that someone who is nervous would give the same responses even if he/she is only afraid that he/she will be thought to be lying.

[Hippy]

Just to get you into the mood, and be a more obvious "liar" on the machine, operators often announce in hallowed and authoritative tones that the polygraph is infallible or 99% true. This subject believes the twaddle and becomes even more nervous when telling the lie.

 

I t's just a bit of showmanship aimed at moulding the mind of the subject to make up for the aproximation of the whole process.

 

[woofgang]

The other issue is that the lie detector measures what people believe, so if you believe that you are lying, then you are likely to register as a liar becuse you will sweat etc, but if you believe that you are innocent then you won't

[Sproutstick]

All true - I also reckon that good ol' Trish ('Independant Woman' - Destiny's Child being her most favourably referenced song in the show - daddyg pointed this out in other thread!!) knows that the lie detector claims of 98% accuracy are grossly exaggerated.  This is why she won't do it on couples who have violence in their relationships (Samantha0 points out above) because if it turns out to be wrong the woman or man in question may get battered to a pulp by their highly educated and intellectually furnished partner.  Just a theory!

[Hebejebe]

They are inadmissable as evidence because certain types of people cannot be detected as lying ie:2% of the population (probably psychopaths).

[Dagman]

We couldn't have that, how would all those poor solicitors and barristers earn a crust? bless 'em  ;)

[hbaldeon]

if a person is cool calm and collective, which is truly rare, there is a possibility that person can pass a lie detector, or under the influence of some type of drug! its a mind over matter typeof thing. people who practice yoga can pass lie detectors 99% of the time.