
The Lie Behind the Lie Detector - giles_corey
https://antipolygraph.org/cgi-bin/forums/YaBB.pl?num=1541951242
======
jpmattia
Every lie detector should begin with a game of high-low: The subject writes
down a number between 1 and a 1000 and puts it in their shoe, the questioner
needs to get the right answer. Since the questioner needs only 10 questions to
get the right answer (+ control questions), it provides a practical
calibration of whether the test is worth a damn or not.

Prediction: No one will ever use my practical calibration of whether the test
is worth a damn or not, until lie-detector technology is actually worth a
damn.

~~~
CobrastanJorji
To play devil's advocate, a lie detector isn't really supposed to measure
meaningless lies. It's about emotion and nervousness and the like. Math
questions about a randomly assigned number would likely not generate much of a
meaningful signal, and thus this test would not be expected to work.

~~~
jpmattia
It sounds like you're arguing that a lie detector only detects lies that the
subject considers "meaningful".

So now you have two problems: Detecting whether a subject believes a
particular topic is "meaningful", and then detecting whether they are lying
about it.

~~~
abandonliberty
You're kind of missing the point of the book: "Polygraphy is not science."
It's an interrogation technique.

~~~
jpmattia
I think interrogators are missing the point: If your interrogation technique
can't even produce information that is verifiably correct, then why on earth
would you believe any information produced that is non-verifiable?

------
module0000
I have taken and "passed" multiple polygraph examinations by US state-level
agencies. Providing truthful answers would have disqualified me in each test,
and I have never been disqualified. This book is very accurate, and has been
my only influence/guide/assistance in every polygraph I have submitted to(ie I
have no "training" in this field). I have not read this new edition, but I
can't say enough good things about the prior ones.

~~~
gnu8
I can’t see how it would be in your interest to post this. Are you not
concerned that this comment could be tied back to your working identity and
used against you?

Another possibility is that you are a lying fed stirring the pot. For
instance, a fed could point to your comment as evidence that antipolygraph.org
is inciting people to break the law, which is a gambit they have used before.

~~~
module0000
Read my comment again please - I'm not a lying fed, a troll, or anything else
malicious. I'm not in the industry I once was, which involved regular
polygraph examinations. I have no plans to return to the industry. Posting my
comment carries zero-to-low risk for me. If it helps even 1 person, then it's
worth it.

All I'm saying is... if you are about to take a polygraph, or think you will
in the near future: _it is in your best interest to read this guide_. On
another note, after you read the guide and possibly benefit from it...you
might find your attitude towards them changed. If the polygraph remains the de
facto "lie detector", then we can all rest easy: because they are trivial to
pass.

~~~
mikeash
Why would I rest easy if they’re trivial to pass? That’s great if I ever have
to take one, but it really sucks if, say, someone passes one while falsely
accusing me of a crime.

~~~
module0000
Polygraph examinations aren't admissible in that way. Otherwise crime would be
as simple as pass/fail not-guilty/guilty.

This is why a (good) defense attorney advises you _against_ taking a polygraph
if one is offered during a trial. If you pass, the case is not magically
dismissed: it's useless. If you _fail_ , you aren't automatically convicted,
but the jury has their view of you negatively influenced by your failure of
the test. You have nothing to gain by taking and passing one in court, but you
have an undefined jury sentiment to lose should you fail.

~~~
int_19h
Isn't the jury view of you also negatively influenced by the refusal to take
it, though?

~~~
sverige
That would not come into evidence as long as you have a minimally competent
lawyer. The jury would never know.

------
mherdeg
Yeah I treat it as "common knowledge" that polygraphs work about as well as
the ADE 651
([https://www.nytimes.com/2009/11/04/world/middleeast/04sensor...](https://www.nytimes.com/2009/11/04/world/middleeast/04sensors.html)).

It's always fun to think about how I could be totally wrong tho. Thought
experiment:

Suppose you had a piece of technology which could infallibly detect whether
someone thinks they are telling the truth.

To preserve the device's maximum efficacy, would you (a) keep it a secret and
only use it for ultra-high-stakes investigations (as with cell-site simulators
- e.g. [https://arstechnica.com/tech-policy/2015/04/fbi-would-
rather...](https://arstechnica.com/tech-policy/2015/04/fbi-would-rather-
prosecutors-drop-cases-than-disclose-stingray-details/) ); or (b) promulgate
the idea that it is worthless or can be trivially manipulated to return any
result, and train people to use it for everything?

Hard for me to distinguish between a world where the polygraph does nothing
and everyone knows it; and a world where the polygraph does nothing and
everyone knows it (but that's just what they want you to think)

~~~
mabbo
It's a fun idea, but even the premise points out the major fault: "whether
someone thinks they are telling the truth".

Studies on memory show that human beings, as a whole, are terrible at
remembering things. We edit, we re-write, we create. Almost certainly some
event you remember clearly from more than 20 years ago either did not happen
at all, happened to someone else and you heard about it, or happened in a
completely different way than you remember. That's true for just about
everyone[0].

What good is a device that can tell if you _believe_ you're telling the truth
when your beliefs and memories are so flaky anyways?

[0] Except my wife, whose near-eidetic memory is frightening.

~~~
Ntrails
> Studies on memory show that human beings, as a whole, are terrible at
> remembering things.

I always remember testifying in court about an assault that took place some
months earlier. By the time I was actually there, I couldn't remember the
event at all. I simply remembered describing the event previously (a bunch of
times).

Did I see what I said I did? I believe so. Was the testimony in court worth
anything at all when compared to the Police interview 2 hours after the fact?
God no.

At that point my truth was that I was confident that I didn't lie in previous
testimony. That's it. As you say - _what value is there in something which
tests that_?

~~~
mabbo
Exactly. What's worse is that society presumes that memory is faultless. If
you honestly said in court that you couldn't remember very well, but that you
believe your statement to be accurate (the truth), a judge and jury would both
agree that you were _less_ truthful, or trying to cover up the truth.

And even if we agree that memory is faulty, no one agrees that _their_ memory
could be faulty. Just everyone else's.

My favourite example of this is my father. He tells a story about some funny
event that happened to him up at his parent's cottage when he was in his 20s.
Right after it happened, he told his family, including his brother. Within a
few years, his brother started telling the story like it had happened to him-
and in fact seemed to believe it _did_ happen to him. My father tells me that
and scoffs, saying "See how faulty memory is? Your uncle remembers an event
that never happened to him!". I asked him "How do you know it's _his_ memory
that's wrong and not _yours_ , since memory is so faulty?" "Oh now, I know
that _my_ memory is right".

~~~
bena
Penn Jillette likes to discuss this. Having worked so long with one person,
they have a lot of shared stories. And he tells of listening to Teller tell a
story and know that he's full of shit, getting nearly everything wrong. And
also having Teller listen to him tell the same story, and thinking he's full
of shit and getting everything wrong.

And then there's the third person or some sort of record of the event that
shows that both of them are full of shit and getting everything wrong.

------
jwally
This American Life did an episode about a guy who was a polygraph operator;
discovered how flawed it was; and has been crusading against them ever since
and teaching people how to beat them. Worth an hour of your day:

[https://www.thisamericanlife.org/618/mr-lie-
detector](https://www.thisamericanlife.org/618/mr-lie-detector)

~~~
ap_org
Yes. That's the story of our friend, Doug Williams, who was targeted for
entrapment by federal agents in a criminal investigation that targeted
polygraph countermeasure instructors. We briefly discuss his case in the
section on "Operation Lie Busters" in Chapter 4 of The Lie Behind the Lie
Detector.

For more on Doug Williams' case, see:
[https://antipolygraph.org/litigation.shtml#doug-
williams](https://antipolygraph.org/litigation.shtml#doug-williams)

------
lbriner
It's scary that something that is not only controversial but also has laws
(e.g. EPPA) in the USA that prohibits its use in some areas (displaying the
lack of faith that the nation has on it), is not completely banned.

If it is not generally used anywhere outside of the USA then it is way too
fragile to be allowed anywhere. The principles are easy to understand but also
easy to falsify as many people have, no doubt, found out to their detriment.

~~~
kevinmchugh
Similarly, SCOTUS upheld the use of drug-sniffing dogs a few years ago. The
research seems to show that the dogs are effectively confirmation bias.

~~~
tlrobinson
At least we don't use dowsing rods:
[https://www.theregister.co.uk/2016/07/26/iraqi_government_fi...](https://www.theregister.co.uk/2016/07/26/iraqi_government_finally_bans_debunked_dowsing_rods_for_explosives/)

~~~
basementcat
Many people and organizations still do. In some parts of the USA, if you hire
someone to dig a well on your property, they don’t dig until someone with a
divining rod tells them where.

[https://www.theguardian.com/business/2017/nov/21/uk-water-
fi...](https://www.theguardian.com/business/2017/nov/21/uk-water-firms-admit-
using-divining-rods-to-find-leaks-and-pipes)

------
gxigzigxigxi
I wonder if a machine-learning approach really would learn how to detect lies.
There is already a huge corpus to train on: police interrogation videos. It
would take significant effort to label deception that was later confirmed. But
I’ll bet we could teach a computer to see through almost any lie if we decided
it was an important thing to spend time on.

~~~
everdev
Maybe if you're looking at non-syntax indicators like pace of speech, posture
adjustments, facial expressions, etc. But NLP is still a major unsolved
problem. AI simply isn't strong enough at understanding meaning especially in
broken English or slang (ex. "Nah, I ain't done it.").

~~~
gxigzigxigxi
I’m not suggesting that the model would infer the truth from the input. Just
that it would render a reasonably reliable estimate that the subject is
dissembling. I don’t think the actual words used would be the principle
component of such a determination.

------
air7
I remember reading somewhere an idea to make the polygraph produce more
objective results:

Instead of asking for example "Did you rob the bank?" and interpret the
response as "lying" or "not lying" they can be asked "Was the getaway car
white?" "Was the getaway car red?" "Was the getaway car blue?". By asking
several of these you can statistically prove the suspect is guilty if they
responded differently to several detail questions about information only they
knew. Tthis doesn't help prove innocence (because people can beat the machine)
but it reduces false positives and can therefor prove guilt (because it's
unlikely a nervous person would randomly be more nervous when the true details
are being asked vs. the decoys).

Of course to be done right the operator must be "blind" (not know the answers
and subconsciously tip the suspect off) and other statistical safe-guards need
to be in place, so how useful in the real-world this is I don't know.

~~~
technofiend
The rational wiki calls it a presupposition and mentions what I remember from
logic class which is to respond "moo" although I could swear it was spelled
"mu" when I learned the term. The example I heard was something like "So tell
the court: have you stopped beating your wife?"

[https://rationalwiki.org/wiki/Presupposition](https://rationalwiki.org/wiki/Presupposition)

~~~
tsuraan
I think the correct spelling is "無", but wikipedia lists english spellings as
"mu" (from Japanese) or "wu" (from Chinese)[0]

0 -
[https://en.wikipedia.org/wiki/Mu_(negative)](https://en.wikipedia.org/wiki/Mu_\(negative\))

~~~
technofiend
Thank you!

------
aphextron
Polygraph testing has nothing to do with the scientific legitimacy of the
actual instrument used. It's just an interrogation technique. Using it
effectively is all about the skill of the person administering the test, and
their ability to judge the person being tested. It is just one part of
building a profile of whether you think someone is lying or not.

The purpose of the test is to put someone through a highly stressful situation
and see how they react to questioning. It's about determining whether they've
been coached, and how familiar they are with details of the case, not
determining a definitive "yes/no" response to specific questions. Polygraph
questions can be passed with 100% accuracy by someone with extensive training,
so it's entirely about building a gut feeling in the person administering the
test as to whether you are lying or not.

------
cafard
"Casey, just appointed C.I.A. chief, told me he was going to challenge Baker
to a polygraph test to show who was lying. Figuring my old pal Casey was the
culprit, I wondered why he would take the gamble. He reminded me he was an old
O.S.S. spymaster, and that by using dodges like a sphincter-muscle trick and a
Valium pill, he could defeat any polygraph operator. Baker wisely did not take
Casey up on the challenge."

[https://www.nytimes.com/2002/10/10/opinion/lying-lie-
detecto...](https://www.nytimes.com/2002/10/10/opinion/lying-lie-
detectors.html)

------
deisner
I also enjoy this: "Why Lie Detectors Don't Detect Lies"
[https://www.youtube.com/watch?v=nyDMoGjKvNk](https://www.youtube.com/watch?v=nyDMoGjKvNk)
\-- 4.5 minutes long.

------
ggm
It's never a good idea to base your feelings about jurisdictional specific
things on this, but the fact that few other modern western economies think
they're worth it bears thinking about: in so much else, law nowadays relies on
everyone else's law to help define how to make it work. So, a new case in the
USA can and will be cited everywhere else as a pertinant example of good
modern law. But.. not in respect of polygraph evidence. Nobody else seems to
want to include it as a routine praxis. Doesn't this worry American students
of the law?

You _could_ apply this logic to the gun control question too..

------
z3t4
Through evolution we have become very good liars. Don't count on your natural
ability to lie though, it's better to just shut up. While lies are next to
impossible to detect, they are easily checked with facts.

------
IshKebab
What about the "lie detector" they had on the recent update to Making a
Murderer? I assume it is also bullshit (and the lawyer who used it seemed to
think that too).

~~~
autoexec
Yeah it seems there are few new ideas for using brain imaging. I haven't
looked into it too much yet, but I strongly suspect they are also garbage
intended to trick people now that a fair number of us are aware of the
polygraph scam

You can get some info here: [http://noliemri.com/](http://noliemri.com/)

~~~
aax888
Let's be real though. With brain imaging, we _will_ eventually be able to
accurately detect lies. This is one of many ethically charged issues where
dismissing it as unreliable/pseudoscience will only work for so long before
one that actually works is built.

~~~
autoexec
I'm not convinced this will ever be the case. Even if we were able to somehow
discover a part of the brain that only ever activates when lying what happens
when someone says something truthful while also thinking of a lie? What
happens when someone technically tells the truth but omits critical
information?

------
dang
Discussed in 2013:
[https://news.ycombinator.com/item?id=6307479](https://news.ycombinator.com/item?id=6307479)

------
thoughtexplorer
I was surprised - and dismayed - that the polygraph was still being used and
given credence with something as high profile as the Ford/Kavanaugh hearing.

I've long been under the impression that it was commonly understood that the
polygraph was fallible. Has this changed?

~~~
ap_org
The U.S. government actively promotes public belief in the pseudoscience of
polygraphy, and the press largely plays along.

~~~
thoughtexplorer
Why is the government actively promoting that?

As for the press, they only play along if it fits their narrative. During that
hearing Fox News framed polygraphs as pseudoscience while CNN was promoting it
as evidence. Both sides will just as easily do the opposite the next time
depending on what their audience wants to hear.

~~~
derefr
Polygraph is a placebo "eye of God watching you" to encourage confessions
during interrogation. No more, no less. Like any placebo, it doesn't work (as
well) if you know it's a placebo.

Either way, it's inadmissible in court. It's a technique for aiding in
interrogation (like torture would be, if it worked), not a forensic technique
for producing evidence.

~~~
User23
Torture does work in cases where the information is verifiable. Consider for
example that the interrogator has an encrypted file and a subject that knows
the key.

Torture is morally abhorrent, but it's not necessarily ineffective.

~~~
billpg
"What's the decryption key?"

"I don't know."

