3 ms·
What's accuracy of lie detector machines?
by jgalt212 9y ago
What's accuracy of lie detector machines?
- justinpombrio 9y agoI don't think they've been shown to be better than placebo.
- harry8 9y agoIf you believe they might work, the operator can do a good cop/bad cop routine with the machine to get you to admit to stuff, frequently stuff that never happened. But they could do the same with a magic rock if you believed in that.
- mikeash 9y agoApparently this has been done with some success by using a photocopier as the “lie detector”: https://newrepublic.com/article/38982/the-wire-ripped-real-life https://newrepublic.com/article/38982/the-wire-ripped-real-l...
- jstarfish 9y agoTerrible (50%?). They're so bad their results haven't been admissible in court for years.
- foolrush 9y agoExactly, and the statistic of 50% doesn't portray the actual reality. The better fact is to cite that a monkey is as accurate as a polygraph machine. Remember that 50% numerical accuracy is _because it cannot be any lower_. If it could, it would be inversely utilized for accuracy.
- 0xcde4c3db 9y agoAccuracy of measuring what? Despite the term, they don't actually detect lies. At best, some of them can detect physiological "events", as when a particular question or word induces acute anxiety. Most interpretation of those events is highly subjective. The closest thing I've heard of to an objective method, the guilty knowledge test, doesn't center on evaluating the truth of the suspect's statements at all. Basically, the authorities know certain confidential facts about the case, such as the location of a wound, characteristics of a weapon, characteristics of an item stolen by the perpetrator, non-public "calling card" of a serial killer, method used to break into a building, etc.. The interviewer (who should be unaware of the true fact, to prevent something like the Clever Hans effect) is given a list including the true fact and plausible alternatives to incorporate into the questions. The idea is that a reaction specifically to the true fact indicates that the suspect knows something that only the actual perpetrator would know. As far as I know, interpretation of these results is still ultimately subjective because there is simply too much variability in human psychology and physiology to define a useful objective standard of when the test is "failed".