How to Beat a Polygraph Test | Hacker News Reader

How to Beat a Polygraph Test

nytimes.com

211 pointsandrewl92 comments

I once had to take a polygraph to be considered for a security clearance. For various reason I didn't want it - I didn't want to join the group of social misfits I knew who worked on classified projects, I didn't want project security telling me where I could go on vacation and with whom I could associate (no foreigners), plus I had a few ethical objections. But at the time I liked my job (lots of great unclassified tech work), wanted to keep it, and needed to go along with my bosses' desires to get me cleared.

The polygraph was administered by a strange guy from a three letter agency. I did the sphincter squeeze for every question. He said the test showed I was being deceptive. I thought that was the end of it and hoped my boss would leave me alone about it. But they called me back to do another one. This time I didn't do the sphincter squeeze. He said the test showed I was being deceptive. I don't know. I think the test just showed I didn't want to get a clearance.

Polygraph operators are superstitious idiots, no better than TV psychics and climate-change deniers. They're a liability to the integrity of our security services, because they are physically incapable of performing a job that they certify has been performed.

Many times they will make comments to get a reaction from you, such as:

"Looks like you are telling the truth.." (even if it shows otherwise)

If you look relieved or surprised, this might be something that they can use at a later date or further along in the interview. Polygraphs are 100% interpretation, they are not binary by any means.

Exactly, it's just an interrogation prop like when the East German police would have the fake telephone where they pretended to make calls to family/friends and verify your story, and had a button under their desk to make the phone ring so they could pretend to get just in time information to refute your story. Modern police will go into an interrogation with a decoy file folder full of random papers and then go through it claiming the contents refute your entire story and you'd better confess too.

A standard polygraph trick is to switch it off, and then have a casual interview during the middle of the test. Then they claim they never switched it off and you've been lying the whole time as your casual results differ on the magic box. Props tend to work to get people to trip up on their replies even if the prop is just a box that randomly scribbles on paper with absolutely zero scientific credibility.

Which is a polite way of saying they're the equivalent of crystal balls and tarot.

life's too short for bureaucrats and games-players

The US is pretty much the only country that uses polygraphs with any frequency. In Europe [1] they are not used. The US needs to stop using the bogus devices.

[1] http://en.wikipedia.org/wiki/Polygraph#Europe

BTW, while I am sure you are talking about developed countries, India is another country that still uses the polygraph test.

Well Wikipeia says it was declared illegal by the supreme court at least to be compelled.

They're mostly discredited here as well. Criminal defendants can't be forced to take them. In virtually all states, defendants can suppress polygraph evidence. In some of the states where polygraph evidence is allowed (by consent of defendants), the defendants apparently also get a civil cause of action against the polygraph vendor.

Unfortunately, we still use them as part of a hazing ritual to get clearance for national defense projects. But the poster upthread is probably right that those kinds of projects aren't the ones you want to be working on anyways.

The interesting thing about polygraphs is that they can be an effective interrogation tool as long as the subject believes they work. (but then again so Santa Claus if the subject believes in him)

For instance the interrogator says, "the polygraph says you're hiding something from me, are you sure there isn't something you want to get off your chest."

The should however, be banned completely because the false positives are so high that we are crippling many of the agencies that rely on them. We're forcing them to drastically reduce their potential talent pool based on pseudo science.

> the false positives are so high that we are crippling many of the agencies that rely on them.

Even worse than that, it selects for people who lie with impunity without any visible or emotionals qualms about it -- basically it selects for psychopaths.

It doesn't do that, because it doesn't work at all. Regular interrogation does that

It does have an effect on subjects who believe it works, it's causes them to believe that the interview knows they are lying. I would expect this to select for good liars among people who believe the lie detector works.

There is no citation for those three sentences. Nevertheless, all it says is that "are not generally used," not that aren't used at all.

It may be informative and entertaining to look at some of these videos on my website:

http://www.polygraph.com/media

And, if you are interested in more, read these essays:

http://www.polygraph.com/index.php?i-don-t-teach-countermeas...

http://www.polygraph.com/index.php?the-lie-detector-is-bulls...

And yes, I am the Doug Williams who is the subject of this article...

These are often used as part of required policy for the US federal government in certain types of security clearances. They seem to be used more as a psychological influence on the person undergoing the clearance than actually working to detect their deception, so I agree with that point in the article.

Case in point, Snowden would have most likely had to undergo at least one of these polygraph tests for the cleared work he did and that didn't exactly prevent anything. Plus, people that are pathological liars can essentially convince themselves that something is the truth which these tests would rarely, if ever, pick up on as deception.

I think the tests do in fact "work" in two senses. First, tons of people with "compromised" histories unsuitable for cleared work freak out and fail or even outright confess things they were concealing. That there's no real lie detection going on is irrelevant. As an interrogation tactic it still functions to some extent.

Secondly, a lot of nervous nellies fail, even though they're squeaky clean. For a lot of the work where the tests are used you really do want to exclude people who can't keep their cool under a bit of pressure. If you freak out under the kind of questioning done, you're probably going to freak out in a way that reveals information if somebody starts asking about your work.

I disagree, and I think that polygraph tests filter out good people in favor of deceptive people and convincing liars.

>For a lot of the work

For a tiny fraction of the work. Maybe you underestimate the number of jobs that use this quackery.

> deceptive people and convincing liars.

My point is that to some extent this is actually a necessary skill. You absolutely don't want people who can't keep cool and put out a bit of smokescreen and do some hand waving.

Now I understand how our government got to be so corrupt.

But most of polygraph gated jobs are boring office work related to (over)classified topics, not jobs that require deception.

The polygraph acts like the pot use question for many US law enforcement positions. People rightly recognize that it's absurd, but for the wrong reasons. It's not there to select for straight edge people who have never smoked up, but to select for people willing to bend the truth for the sake of making procedures have the expected outcomes. Law enforcement doesn't want the guy who feels compelled to cost himself a job by being honest about a roach when he was 14, not because he did something illegal, but because when asked on the stand whether he's confident evidence bag #14 never left his sight he's likely to let the truth get in the way of the legal machine.

The polygraph foremost is a way to arbitrarily filter people for reasons that interviewer would rather not reveal, and secondly to select for people willing to put up with the theatrics of procedures while being indifferent to their supposed purpose.

>> The polygraph foremost is a way to arbitrarily filter people for reasons that interviewer would rather not reveal, and secondly to select for people willing to put up with the theatrics of procedures while being indifferent to their supposed purpose.

That... That was beautiful!

I like your theory, but do you have any first hand knowledge or is this just logical reasoning?

That's a fine theory but it isn't the reality at all. The people using polygraphs don't have that level of conspiracy cleverness.

Systemic bias doesn't require that everyone in the system (or even anyone in the system) be cognizant of the bias, only that the bias selects for qualities that will reinforce the same systemic processes. People that consent to polygraphs despite their obvious flaws and interact well with people willing to conduct them despite those same flaws are more likely to continue or encourage the use of polygraphs than others. It doesn't require conspiracy. At the same time, the continued use of polygraphs for so long given how public and documented their flaws are allows us to ask what actual selective function they are serving in the system. Besides institutional inertia, the only two compelling explanations are as a proxy for biases of the polygraph operators (which must play a part given that polygraphs are not deterministic, robust detection mechanisms) and as a selective pressure for people who don't have qualms with these types of systemic dysfunction.

You're either severely underestimating how often polygraphs are used, or severely overestimating the level of stress those jobs will be put under.

So basically the best way to pass is to be a PPI–1 psychopath.

Never been polygraphed but I always wondered about an alternative to the "emotional control" approach to beating it that is discussed in the article.

My alternative would be to trick my mind into not lying despite the question asked. So if I was asked "do you live in Chicago?" (i don't) and I wanted to answer yes, I would simply internally ask myself "is your name loteck?" and then respond "yes."

I would ignore the actual question asked by the interviewer except to the extent I need to pick which internal question I would ask myself, of which I would only have 2. One for yes responses and one for no.

Anybody have any idea if this would work?

I'm definitely not an expert in the area (never even taken a polygraph), but I highly doubt you could prevent yourself from getting nervous/agitated when asked a question about something you had to lie about.

Don't think most people are that good at controlling their emotions, even if the question in your head is different you still know what the intimidating investigator actually wants to know.

Lying on control questions is not advisable. A polygraph would be conducted inside of a larger investigation which would, among other things, fact-check your claims by other means. These data would be considered in the interpretation of your polygraph results. Whether or not you live in Chicago is very easy to check; when they see that you are lying on control questions they will consider everything else suspect.

In the contexts in which polygraphs are applied (i.e. security clearance, witch hunts within security services), simply being suspicious in this way is enough to cause the negative outcome (i.e. not getting the clearance, getting fired), so even if it might muddy the evaluation of your response to, i.e. "Are you a Russian spy?" it would still cause the negative outcome.

It has no bearing on criminal prosecution, because polygraphs are already inadmissible.

If you lie on a question that is easily fact-checked, and the polygraph shows that you told the truth, doesn't that just prove that the polygraph doesn't work?

To my mind that is a simple test that disproves the effectiveness of the tool. It should cause a reasonable person to conclude that the tool doesn't work and should not be used.

The people who run these tests for a living probably have techniques to explain their way around stuff like that. They might say it just shows the subject was deceptive about the whole test.

>It should cause a reasonable person to conclude that the tool doesn't work and should not be used.

But it is likely to cause an FBI-drone to conclude that you are attempting to beat the polygraph and therefore untrustworthy.

Yes, what a strange situation. I lie to prove that the machine can't tell that I'm lying and am branded a liar for revealing the truth.

Maybe the machine isn't meant to do anything, and it's the examiner judging whether you are lying based on how your react to its presence.

I wonder if polygraphs are there as a cover for refusing clearance due to secret evidence. If you know bob is a Soviet spy because your agents in Russia say so, you don't want to blow their cover, so you need an arbitrary reason to refuse clearance.

IANASpy, but my understanding is that even someone with clearance can't just look at whatever she wants. So we probably want to give a mole an arbitrarily high clearance, and just make sure she looks at top secret fake documents we've cooked up for her.

Is this aspect of security work that makes me wonder in the back of my mind whether Snowden is a modified limited hang out.

It's an intriguing possibility, but my imagination is unequal to the task. If they didn't mind showing us all this evil crap, what horrific secrets are they actually hiding? Secret pacts with Cthulhu? Hitler was actually a USA agent? Nothing big enough seems plausible.

Well, it could be cold war thinking, a line from Dr Strangelove gives one plausible reason.

"Of course, the whole point of a Doomsday Machine is lost, if you keep it a secret! Why didn't you tell the world, Eh?"

Benway's panopticon only functions if the inmates think they are watched. The secret might be that they cannot actually process all the data and are overwhelmed by the sheer quantity of it, in which case the surveillance is more useful if people think they can.

IANASpy either, but I've worked on some cleared projects. Clearance (and need to know) _is_ what we use to determine what someone can look at. If a co-worker needs a document, I verify that he's cleared for it, then I give it to him. There is no alternate system where I can look up: "Bob has a Top Secret Clearance, but also a spy so don't share anything with him."

There is a popular misunderstanding that having a top secret clearance means you automatically have access to all top secret information. When in fact it just means that it might not be illegal to give you access to particular documents.

Parent is getting at the fact that it is entirely possible to have a Top Secret clearance and never be granted access to any interesting information.

My guess is that your body would somehow react to the idea that "hey, this is a question I need to cheat on!" in some measurable way.

I should say up front that, as others have said, polygraph is all superstition and subjective interpretation when it is being used seriously. Usually, it's just a prop to scare people with in an interrogation. The following comments are what the "true believers" of polygraph usually believe, and is probably a key part in how an examiner judges a polygraph exam, but you can never really rule out the possibility of an exam being a simple scare tactic or cover for subjective opinion. With that risk and the fact that this is all disproved junk science, YMMV.

Any question that can be trivially checked such as "Do you live in Chicago?" is not one of the "control questions". Questions like that are part of the theater for the benefit of the person being tested. Like the waving needles, it makes the test look more complicated and "scientific" (really: "it's complicated" and therefor "magic" in the sense of Clarke's 3rd Law).

The article has an actual example of a typical control question: “Have you ever lied to anyone who trusted you?”. Unfortunately, their explanation that "...an innocent person telling the truth will have a stronger reaction to the control questions..." misses the point entirely.

Control questions are always about a "little white lie" that the examiner assumes is something that everybody does. The important thing to understand about the real "control questions" is the assumption that you will lie when you answer those questions. In the question from the article, the assumption is that of course you have lied to someone who trusted you, but you will say "no" out of fear.

The "theory" is then to look for a difference (ANY difference, not just a "stronger reaction") in the polygraph output for that question when compared to most of the rest of the questions. This is then used as a reference to see if something similar happens on a real interrogation question.

Want to mess with the test? Don't lie on the control questions. Admit to the "little white lies" they assume are said by everybody. This will usually do two things: 1) it will invalidate the test, and 2) it will piss off the examiner. Obviously, the utility of forcing these results will depends on why you're taking the test.

If instead you want to do the opposite and "pass" the test without suspicion, remember you're being recorded from the moment the sensors are put on. Make sure their machine records regular (small standard deviation) data except for when you give the expected lie. If they see the expected "change" on the correct "little white lie" (control) questions, and not much anywhere else, that should be seen as a "pass".

Or even better, don't perpetuate this nonsense and refuse to take any polygraph tests.

When I was a kid, the polygrapher for the local maximum security prison was a member of the family church. He came in to school one day and did a demo for the kids. One memorable thing he said was that during an examination, there is only one lie detector in the room, and it isn't the machine.

And there is at least one liar in the room, but it isn't always the interrogatee.

I've never taken one. Question: if you're fundamentally convinced that polygraphs are hokum (as I am), do you actually need any tactics to "beat" them? Or can you just ignore them and handle the interview the same as you'd handle any other interview, and just sort of smile and shrug when the "operator" tells you the machine spat out some significant result? ("Huh, maybe I just had to burp.")

>do you actually need any tactics to "beat" them?

Maybe. Tactics aimed at fooling the machine are really only to bolster the confidence of the person being tested. It's not the case that you're playing against a machine though, the machine doesn't "do" anything; it's a game that you're playing against the examiner.

Right. But polygraphs really are hokum. If you don't doubt that fact, what advantage does the examiner have? Is it that I'd have to account for the fact that they might irrationally believe in the machine, and adjust my performance to fit that irrational belief?

I think what I'm getting at is that the notion of "cheating" or "beating" a polygraph seems like it dignifies the procedure. It's a little like "beating" a psychic medium, isn't it?

What makes you think that the polygraph examiners "believe" in the machine. I'm pretty sure most of them don't. I wouldn't always assume good faith on the part of the examiner, either. In the common use case of culling the herd of police job applicants, polygraph examiners are there to provide a way to arbitrarily reject certain applicants. So, in that case, the applicant basically has to make the examiner "like" him.

It's better than "beating" a psychic medium because there is often a real, valuable prize to be gained (ie: a job).

As far as I am concerned, even submitting to examination dignifies the procedure too much.

If the polygraph examiner doesn't believe in the machine and the candidate doesn't believe in the machine, I'm a little lost as to how the examiner has any advantage, or why you would need any special techniques to "beat" the process.

To be clear: I don't think you do need those tactics, but I'm asking, not asserting; I've never taken a polygraph.

Based on other comments in the thread and other things I've read, it seems like the polygraph machine serves only to intimidate the interviewee into wearing their emotions on their sleeve, and the real purpose of the polygrapher is to try to read body language.

It also sounds like polygraphers may think they are reading someone, but in actuality just injecting their own bias. I have also never taken a polygraph, but maybe the process to beat is the bias of the interviewer, not the machine.

Right! So isn't it weird to see us proposing things like new tricks to beat the machine? What machine? Can't I just imagine it's a Magic 8 Ball instead? Would we propose tricks to beat a Magic 8 Ball? No!

> What machine? Can't I just imagine it's a Magic 8 Ball instead?

I mean, measuring perspiration, pulse, breathing, and movement is perhaps a step above a Magic 8 Ball. I too am entirely doubtful that anyone can reliably detect deceit with those measurements, but it's hard to have a nonchalant attitude of "this is just a silly game" when you're connected to devices that do in fact actually measure those things.

The presence of the machine changes the nature of the interview. It's like how being interviewed on the phone at home and being interviewed handcuffed to a table with a gun your head are different. It really doesn't matter much if the interviewer actually intends to shoot you or not. The mere presence of the prop induces stress making it difficult to think clearly and avoid being manipulated by the interviewer.

To succeed in the situation your mind must be prepared to deal with the gun or the handcuffs or the polygraph. I doubt many people are able to simply ignore them.

The advantage is in them hoping you don't know that machine doesn't work.

In fact they try to check for it. Like they might say things like "it looks like you pizza-ed on this one when you should-a frenchfried, ... hmm that's interesting'. Where say "pizza" and "frenchfry" are polygraph specific terminilogy. If you don't ask "hey what does that mean?" they might assume your read up on and research about how to beat polygraphs.

And on your point of "what if I really don't believe in polygraphs". The problem is the polygraph measures involuntary emotional response. You might rationally not believe in efficacy of polygraphs. But emotionally you'd start breathing faster anyway. Maybe because you are afried the polygraph examiner will figure out that you really know how polygraphs work.

So if that's the only advantage, I can ignore all sphincter-related advice, and the polygraph itself as well. I'm happy about that outcome, by the way!

> I'm pretty sure most of them don't.

Curious.. Why so sure?

For me it would be a matter of personal strategy. Basically, is standing on principle the most strategic thing I can do given my goals in the situation that left me on the receiving end of a polygraph?

Even if my strategic goal is to show that a polygraph is meaningless, being able to pass or fail one at will could be really useful to that end.

The odds seem pretty low that any job or clearance requiring a polygraph would let you get by without one, even if you displayed an extensive knowledge of them and how they're flawed. Personally, if acting on principle, I'd probably just not want to work at a place like that to begin with. Of course, I'm sure there are some highly sought after individuals that could get by with that, and it probably depends on whether or not the organization you're engaging with views the polygraph seriously or as a relic on its way out.

If it were something to do with legal proceedings, I'd have to talk to a lawyer first, and see what was in my best interest.

As far as term semantics go (which I think are important), maybe "manipulating" would be a better word than "beating" or "cheating"

edit: The sibling poster also has a really good point about everyone possibly knowing it's a sham, but using it as a tool to get rid of people they want to get rid of. That might be more likely than all my speculation

Ok so I think we may be talking past each other here. I'm not arguing about the legitimacy of polygraphs. They're hokum.

I'm keying in on things like "being able to pass or fail [a polygraph]". "Able" to "pass" or "fail"? Would you say the same thing about being able to pass or fail a psychic palm reading?

I feel like I'm missing something, which is why I keep asking.

> Is it that I'd have to account for the fact that they might irrationally believe in the machine, and adjust my performance to fit that irrational belief?

Well, yeah, wouldn't you? I mean, the fact that you're being given a polygraph implies that your interrogator believes it has some effect that benefits them. And if you're completely convinced that that isn't true, meaning the human-with-polygraph is not more reliable than an unaided human, that still leaves the possibility that the human-with-polygraph is worse in a way that affects you.

If there's a possibility for the device to convince your interrogator that you're being deceptive, but you're honest, you're taking a risk unless you attempt to avoid causing a false positive. Conversely, if there's a possibility for the device to convince your interrogator that you're being truthful, and you're deceitful, you're missing out on an advantage unless you attempt to cause a false negative.

There's no case where your interrogator is better off, so your premise isn't invalidated; the polygraph itself is still bunk. But it's your interrogator's trust in it which has created a relative advantage for you if you play along.

The exact same applies if they show up with a "psychic", although it might be harder -- or easier -- to manipulate.

The problem is the operator is trying to unnerve you and embarrass you, specifically to fluster you. They don't just just ask you the questions they're interested in. They ask you about your personal sexual habits and other things designed to trigger an emotional response. It's all just a sham. The more honest of a person you are, the less likely you are to pass the polygraph on your first try. And the only way the polygraph works to catch out liars is to use the shame of the situation to coerce a confession out of the person.

Say they ask you "have you engaged in homosexual behavior, especially under the age of 14?" Most people I know, given the situation, will blush. And blushing is basically all a polygraph can actually measure. So now they start berating you that you lied, and if you continue to insist you didn't lie about that particular question, they say it means you lied about a previous one.

The only way to pass a polygraph is to know what they are like and just get through it. Honest people and liars both just need to stick to their stories, regardless of what the polygraph is saying, because eventually they will just fail you and schedule you for another one. Repeat until you've been through it so many times it doesn't phase you anymore. Then their job is done, their job being, "it wasn't my fault if you turn out to be a spy."

Sure! But there are lots of situations in which a counterparty in a discussion has an off-putting advantage (see: every job interview), and yet we don't generally offer advice to candidates along the lines of "tense and relax your anal sphincter repeatedly" or "visualize your happy place on target questions and your worst nightmare on control questions".

Is where I'm going with this clear? I feel like I'm just confusing everyone with this line of questions.

I'm literally just asking:

If I was given a polygraph tomorrow, knowing what I know now (in fact having conviction about what I know about polygraphs), wouldn't a reasonable strategy be to ignore any polygraph-specific advice, and manage the process the same way I would if there was a Magic 8 Ball adjudicating it?

I know there are differences between the plastic toy and the fortune-telling billiard-ball, but are they meaningful?

A magic 8 ball would be just as effective of a prop in the play that polygraph operators play.

When I was in high school I applied for a job in a VW performance shop a couple miles from my school. They sent me to the owner's neighbor for a polygraph, which surprised me but didn't seem like a big deal at the time. The guy was playing 'bad cop' from the second he answered the door, and said he was disappointed that I hadn't smoked pot on my way over because that makes reactions more visible on the polygraph.

We went through his questions 3 times. The first time I just answered his questions, no games. The second time I tried to change my anxiety level sort of randomly (I had some experience with pretty high-end biofeedback equipment and knew how to affect the readings somewhat). The third time I used a breathing exercise that I was taught by a zen master to minimize my anxiety as much as possible.

The polygraph operator was pissed, I decided that I had no desire to work for people who thought that was a good use of 45 minutes, and I didn't get the job.

Everybody won, I guess.

I would love to see polygraphs calibrated with a simple game of hi-lo. Pretty simple metric: Pick a number 1-1024, the questioner gets it right or wrong.

To get security clearance you need to go through government sponsored auditing. They don't want any thetans to get access to state secrets.

The polygraph is quackery. They may as well just phone Miss Cleo and ask her if someone is lying. But good on them for pointing out how they are still used to coerce people.

Given that the test is essentially measuring whether you respond to a question with an adrenaline burst, I wonder if taking beta blockers prior to testing can influence the results. That would be my first instinct.

Some places test for drugs in your system along with the polygraph test since beta blockers are sometimes used to help beat the test.

Well, this is the first thing I would think of, if I wanted to cheat on a polygraph test.

Obviously I would just try to be more nervous at the control questions, to establish a baseline that wouldn't make the lies stand out. I'd imagine I'm lying on the control questions.

I always thought George Castanza had the best polygraph beating strategy. "It's not a lie, if you believe it."

"Jerry, just remember: it's not a lie, if you believe it."

https://www.youtube.com/watch?v=vn_PSJsl0LQ

The ol' tack in the shoe trick was specifically noted as bunk by the examiner I knew, and the sphincter clench is semi-widely known.

What I would find difficult with each of these tricks, is that you have to execute them during control questions, and not during "real" questions.

Keeping track of when to clench or not while simultaneously trying to keep reality, and one's deceptions straight seems like it would be extremely hard to do under even mild pressure.

Plus you'd probably have to remove your shoes and there'd probably be a force sensor under your butt.

Not to be too much of a truther, but a polygraph examiner has no interest in admitting that their work is bunk.

Perhaps he was a bit honest. These things happen sometimes.

If I recall correctly this book has an interesting section on polygraphs and a lot of other inaccurate methods and folklore around detecting lies and deceit:

http://www.amazon.com/Detecting-Lies-Deceit-Pitfalls-Opportu...

It was really interesting when I read it, though it's a bit old now, so I'm not sure how much of the material needs to be updated.

The only way to win is not to play. If you are ever in a position where you have to take a polygraph test, you have already failed.

The only way to win is not to play

This is often forgotten. In so many situations in life, people think they must make a choice being forced on them, "yes or no" or something similar.

Quite often the best choice is not to not allow yourself to play that game. Instead, learn to "think outside the box".

This is a great article! There's a reason that polygraph tests are not normally allowable as evidence in court!

It does seem much more similar to psychological torture than actual conclusive detective work...

you say that like there's a difference :)

this is another version of the "machine learning" prob isn't it? the machine collects a bunch of basic physiological variables and makes a prediction, you just have to figure out what those variables are, whether it's hr, bp, etc

Excellent resource on the pseudoscience of polygraphs: https://antipolygraph.org/

One of my high school students who was an ex detective taught my class how to beat them.

He said put a thumb tack in your shoe, and when asked each question, step on the tack slightly, enough to cause pain. A lie registers as a blip, but so does pain. If every question has a blip, they cannot differentiate.

> He said put a thumb tack in your shoe

The examiner can just require subjects to remove their shoes.

> One of my high school students who was an ex detective

I read this many times. Can you expand on how a detective ended up as a highschool student? Sounds like a fun story.

> One of my high school students who was an ex detective

Should be

"One of my high school teachers..."

Polygraphs are about as useful and effective a tool as water-dowsing rods.

There's an incorrectly joined infinitive in the second sentence.

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