Polygraphs

[Oldandeasilyconfused]

As far as I've been able to find out, the science and reliability of polygraph are dubious at best. Eg polygraph results are not accepted as evidence in most courts of law.

Are these tests as widely used as many TV shows imply?If so,why,and why would anyone agree to take one? I would not.

[theVOID]

Absolutely, I've done a fair bit of research on them after a friend insisted their efficacy was 98% (I think he watches too much Jeremy Kyle), the best meta-analysis I found showed that the efficacy was more like 60%, that demonstrates that the biometric factors analysed by the machine (given certain methods of questioning) was correlated with lying but the analysis found they could also be caused by 18 other distinct mental states from nervousness, jealousy, anger, flu, anxiety etc.

Interestingly, when a husband and wife had accused each other of cheating but both insisted they had not and were both being tested simultaneously but in different rooms their chances of triggering a response were about 98%, it seems that worrying about the results your partner would get triggers a far stronger response than an innocent person who is worried about failing the test.

Another interesting point was that the people who claim to detect lies via facial signals, speech and other mannerisms (such as the show "lie to me") were MUCH more effective than the polygraph. Listening to people respond to questions was much more likely to yield an accurate result, from memory it was about 78%.

*Sorry, I've been trying to find the PDF that I thought I had bookmarked but I can't find it*

The Skepdic article is pretty good; http://www.skepdic.com/polygrap.html

There is also an episode of the TV series by Michael Shermer that covered it;

http://www.youtube.com/watch?v=GLL3wtgBiFA

I would never agree to take one of these tests, be it for a trivial or serious matter. Anyone who uses them is a fucking fool, basically.

[The Grand Nudger]

It makes for good daytime TV. It's relatively inexpensive for the studio, and it does have the patina of authority for those so inclined to daytime TV.

[Autumnlicious]

TheVoid summed it the best.

My two bits are -
a) Assume the polygraph detects states favorable to 'lying'
b) Sociopathic behaviour exists
c) The person needs to simply believe in their story.
d) Instant fools.

So even if the polygraph was 100% correct in detecting set states associated with lying, simply believing or 'rewriting' one's own version of history easily circumvents such.

Aka - if one isn't convinced by Void's statements about the efficacy, one should be convinced by sociopathic behavior, which is quite, quite common.

See also - believing in a magic sky wizard.

[paintpooper]

I always saw that as a problem with polygraphs. Most honest good people would just admit their wrongs and never reach the point of taking a polygraph.

A sociopath could quite possible pass with flying colors as they have weak emotions and some have no ability to feel empathy or remorse, so basically they can lie and their physiological body with not react, in a way a sociopath can never lie (to themselves), because everything they say they think is the truth. Pretty sick stuff if you ask me.

I have met a few sociopaths/psychopaths, and you are right, they are much more common than one would think. I think the name "sociopath" scares people, but it is a common trait, and no one will think there friend or family member is a.... *gasp... sociopath.
And I have to agree 100% on facial and body language reading. When you continue to push someone they will give clues. And sometimes just looking into their eyes you can see right through... scary.

[thesummerqueen]

I think a pretty telling example is the polygraph's use on Monster Quest. The person running the machine would come back with results all the time saying the person "had no intention to deceive." Basically - you could say the person was telling the truth about bigfoot (or werewolves, or etc). Or, you could realize these people THOUGHT they were telling the truth because their brain fooled them. Some girl really thought she saw a werewolf down by the river. Doesn't mean it's the truth. Using it in a legal preceding is just irresponsible then - if a person plans to take a polygraph based on what they *thought* they saw, and it comes out "truth," it should hardly be admissible evidence.

But, we like our crime dramas to be wrapped up neatly. I noticed SVU started commenting on its ambiguity though.

[Napoléon]

DAMN YOU JEREMY KYLE

All those times he's said "I stand by that test"