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Better and worse ways to spot a liar

bbc.com

11–20 of 152 posts

Re: Better and worse ways to spot a liar

#11
> Study after study has found that attempts – even by trained police officers – to read lies from body language and facial expressions are more often little better than chance.

Yet juries in rape trials supposedly do it all the time...or don't they?

Re: Better and worse ways to spot a liar

#12
post #6

So, what's the rate of false positives, given that only 1 in 1000 is a true positive?

From the source: "CCE agents identified 24 times more mock passengers (66%; 60% at Month 1 and 72% at Month 6) than suspicious signs agents (3%; 6% at Month 1 and 0% at Month 6)" ... "base rates of identification of genuine travelers identified as being deceptive in the 6 months before the trial (1 in 1,247 passengers) did not differ during the trial with suspicious signs (1 in 1,219 passengers), or CCE (1 in 1,295 passengers)"

So my reading is 2/3 mock passengers identified as true positives, 1/1000 real passengers identified as false positives.

(With some provisos as noted in the paper)

Re: Better and worse ways to spot a liar

#13
post #11

> Study after study has found that attempts – even by trained police officers – to read lies from body language and facial expressions are more often little better than chance. Yet juries in rape trials supposedly do it all the time...or don't they?

Why single out rape trials specifically?

Re: Better and worse ways to spot a liar

#14
post #13
post #11

> Study after study has found that attempts – even by trained police officers – to read lies from body language and facial expressions are more often little better than chance. Yet juries in rape trials supposedly do it all the time...or don't they?

Why single out rape trials specifically?

Are any other kinds of trials little more than a game of spot-the-liar?

Re: Better and worse ways to spot a liar

#15
post #13
post #11

> Study after study has found that attempts – even by trained police officers – to read lies from body language and facial expressions are more often little better than chance. Yet juries in rape trials supposedly do it all the time...or don't they?

Why single out rape trials specifically?

Rape is interesting in this regard because it is an especially severe crime that might be very hard to proof. Murder has a body and a weapon, but rape might be indistinguishable from consensual sex, when you just look at hard physical evidence (medical examination, text messages, ...). If you want to give justice to most rape victims, you have to decide who is lying, and who is saying the truth.

Re: Better and worse ways to spot a liar

#17
post #15
post #13

Earlier quoted context omitted.

Why single out rape trials specifically?

Rape is interesting in this regard because it is an especially severe crime that might be very hard to proof. Murder has a body and a weapon, but rape might be indistinguishable from consensual sex, when you just look at hard physical evidence (medical examination, text messages, ...). If you want to give justice to most rape victims, you have to decide who is lying, and who is saying the truth.

> If you want to give justice to most rape victims, you have to decide who is lying, and who is saying the truth.

It is also possible that both victim and rapist are telling the truth, but it still is an open question if it's a rape. Example: Julian Assange case with the broken condom.

Re: Better and worse ways to spot a liar

#18
post #15
post #13

Earlier quoted context omitted.

Why single out rape trials specifically?

Rape is interesting in this regard because it is an especially severe crime that might be very hard to proof. Murder has a body and a weapon, but rape might be indistinguishable from consensual sex, when you just look at hard physical evidence (medical examination, text messages, ...). If you want to give justice to most rape victims, you have to decide who is lying, and who is saying the truth.

Most white collar crimes also fall in that category. Was it pure negligence or was it engineered ?

Re: Better and worse ways to spot a liar

#19
Not sure if trying to "trap" the liar is always the right way to go. Once I had to work with a freelance web master and we were trying to cancel his contract and make him transfer the domain name to us (an association I was working for). I confronted him by asking politely for a written copy of his contract because I thought he was lying about the length of the contract. He was insulted and claimed there was a verbal agreement several years ago. I don't know if he was right or wrong about that, but after that he would make up things about basically anything (such as, that changing the owner/registrar of our domain would cause his other customers' files to be deleted etc.). We now offered him money to break out of the "contract" early, but now he was already stuck in his lies. If he would say that it was technically possible to move the domain name, he would also expose his earlier lies.

After almost a year of arguing with him, he offered to transfer the domain before the end of the "contract". But for "technical reasons" it had to be done after the hosting company had shut down the web site and e-mail, which caused some downtime for us. In retrospect it would have been much easier if I hadn't questioned him in the first time.

Re: Better and worse ways to spot a liar

#20
post #7
post #2

> According to one study, just 50 out of 20,000 people managed to make a correct judgement with more than 80% accuracy. Most people might as well just flip a coin. Oh the irony surrounding statistics and how often it is used to lie - case in point: the mode is completely absent and some useless factoid is presented instead. That's not to say that argument is false ("you can't use body language"); merely that because…

After a bit of searching it's probably this study: https://en.wikipedia.org/wiki/Wizards_Project#Synopsis Granhag, Pär; Strömwall, Leid (2004). The Detection of Deception in Forensic Contexts.

No, that's from 11 years ago.

The actual paper was linked lower down: https://news.ycombinator.com/item?id=10180932

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