11 ms·

Aren't lie detectors junk science?

varjag 8y ago
In the same way statistical spam filters are junk† science. They suffer from false positives/negatives issues, but they perform a lot better than coin toss. † Granted spam filters literally deal with junk..
- lawn 8y ago
  Not arguing either or but a coin toss is a very low bar.
- greenhatman 8y ago
  >but they perform a lot better than coin toss I'm curious how that was tested. And if there is a source for this.
germinalphrase 8y ago
Only if you think their purpose is to detect lies.
raincom 8y ago
It is not 'junk' as long as Federal Agencies use it!!
deleted 8y ago
[deleted]
joshvm 8y ago
They're based on the idea that if you're made to tell a lie, your body will react in some way (sweating, faster heartbeat etc) compared to a baseline measurement. There is a whole field of psychology around lying and additionally agents are ostensibly trained to detect visual cues that someone is telling a lie. The premise isn't exactly junk - hardware lie detectors are basically trying to identify a fight or flight reaction, which some people will exhibit when lying. Have you ever been confronted with a fact (did you eat that cookie?), lied, and felt a rush or a feeling of panic? That's what lie detectors try to detect. The problem is it's possible to fool a polygraph and it's prone to bias. For example some people get nervous when asked a question, even if innocent. It's theatre in some sense, and it shouldn't be assumed as 100% accurate, but there are plenty of people who will break out into a cold sweat when you ask them a question they don't want to answer truthfully.
- greenhatman 8y ago
  It's borderline useless. And can do lots of harm if assumed that it's useful.
  - joshvm 8y ago
    I wouldn't disagree with that. And a big problem is that innocent people tend to produce stress reactions when interrogated, leading to false positives. It would be appropriate to call a polygraph a "fear" detector, since that's basically what it's measuring. But still, the "science" isn't entirely bunk: some people do panic when they lie - though I read an anecdote that said this is a weirdly American trait (Europeans can cheat the polygraph more easily) - but it's virtually impossible to sift out the true positives from the noise.

In the same way statistical spam filters are junk† science. They suffer from false positives/negatives issues, but they perform a lot better than coin toss. † Granted spam filters literally deal with junk..

lawn 8y ago
Not arguing either or but a coin toss is a very low bar.
greenhatman 8y ago
>but they perform a lot better than coin toss I'm curious how that was tested. And if there is a source for this.

germinalphrase 8y ago

Only if you think their purpose is to detect lies.

raincom 8y ago

It is not 'junk' as long as Federal Agencies use it!!

deleted 8y ago

[deleted]

joshvm 8y ago

They're based on the idea that if you're made to tell a lie, your body will react in some way (sweating, faster heartbeat etc) compared to a baseline measurement. There is a whole field of psychology around lying and additionally agents are ostensibly trained to detect visual cues that someone is telling a lie. The premise isn't exactly junk - hardware lie detectors are basically trying to identify a fight or flight reaction, which some people will exhibit when lying. Have you ever been confronted with a fact (did you eat that cookie?), lied, and felt a rush or a feeling of panic? That's what lie detectors try to detect. The problem is it's possible to fool a polygraph and it's prone to bias. For example some people get nervous when asked a question, even if innocent. It's theatre in some sense, and it shouldn't be assumed as 100% accurate, but there are plenty of people who will break out into a cold sweat when you ask them a question they don't want to answer truthfully.

greenhatman 8y ago
It's borderline useless. And can do lots of harm if assumed that it's useful.
- joshvm 8y ago
  I wouldn't disagree with that. And a big problem is that innocent people tend to produce stress reactions when interrogated, leading to false positives. It would be appropriate to call a polygraph a "fear" detector, since that's basically what it's measuring. But still, the "science" isn't entirely bunk: some people do panic when they lie - though I read an anecdote that said this is a weirdly American trait (Europeans can cheat the polygraph more easily) - but it's virtually impossible to sift out the true positives from the noise.