Lie Detector Test Procedure

Zannan said:

My MC takes a lie detector test to prove he didn't murder his cousin.
Even though he's telling the truth, he fails the lie detector test since he's nervous since he could be executed and angry his cousin's murderer is framing him.
What's the procedure for a lie detector test?
After he fails the test do the cops escort him out?

Click to expand...

There is plenty of stuff on the web about how Polygraph machines work. Here's a few links from a 10 sec Google search.

http://people.howstuffworks.com/lie-detector.htm

http://www.apa.org/research/action/polygraph.aspx

http://home.total.net/~galcar/html/polygraph_procedures.html

http://www.apa.org/research/action/polygraph.aspx


Note that in many states the results of a Polygraph test are not admissable in court. Check the state you set your story in.

As for "the cops escorting him out," what do you mean? Are they just escorting him out of the police station or wherever the test was administered or are they arresting him?

I doubt a test by itself would be enough to arrest him. If he's just leaving the PD his lawyer will likely escort him out. The police may also do so if there is concern he will go somewhere unauthorized. Otherwise it's more likely it's a "there's the door" sort of situation.

To write knowledgeably about lie detector tests, you're going to have to read some of the textbooks on the subject.

However, your premise has a serious flaw. The subject goes in and talks to the examiner. The examiner explains what is going to happen and shows the subject the machine. Then the examiner hooks up the machine, again explaining the machine. Then calibrating questions are asked, with some questions the examiner knows the subject will lie about.

If at that point the subject continues to be angry or nervous in a way the examiner cannot clearly identify, the examiner should cancel the session and explain that the subject is not a suitable person for a lie detector test.

If the test continues with those emotions, the subject would not test positive for untruthfulness, but would have an inconclusive test. He would not "fail" the test. The only result would be that he did not "pass" the test.

Also, you need very specific questions to ask, with a yes or no answer. For example, a question like, "Did you stop at the stop sign on Elm Street on Friday afternoon?" Inappropriate question would be, "Do you stop at stop signs?"

Best of luck,

Jim Clark-Dawe

Zannan said:

My MC takes a lie detector test to prove he didn't murder his cousin.
Even though he's telling the truth, he fails the lie detector test since he's nervous since he could be executed and angry his cousin's murderer is framing him.
What's the procedure for a lie detector test?
After he fails the test do the cops escort him out?

Click to expand...

Several things -

A polygraph doesn't prove (or disprove) anything. Legally, it's fairly useless, though, you know, funsies.

Being nervous shouldn't lead to the wrong result if you have a good examiner.

Google is your friend.

Escort him out of what, where to what, where?

Mostly what jclarkdawe said.

Lie detector tests are not admissible as evidence, and they can't prove or disprove anything, only indicate that a subject's answers were consistent or not consistent. And they're subject to all sorts of confounding factors. Scientifically, they are bogus.

Read up on polygraph examinations and how they work. They are nothing - nothing - like what you see on talk shows. Those scenarios are pure fabrication.

But... But Jeremy Kyle says they're 96% accurate, and he's our version of Jerry Springer so he must be right!

It might be useful to understand what lie detectors are actually used for; their real goal is to make the subject believe we will know if they lie, so that they volunteer a confession.

It's one way (among others) to get around the legal ban on coercive self-incrimination.

Even if you're an honest person they make you experience guilt for every sin since man stood upright. I've endured several for a job I had before retirement, passed every one, but I'd rather deal with a root canal than that experience again. Your mouth turns to cotton, they strap a blood pressure reader on your arm and pressure the cup until it hurts, loop an expansion loop around your chest to monitor breathing, then ask the same questions over and over (at least three times) and finally toss in a trick question just to trip you up. Yeah, it sucks. Least that was the process ten years ago. May have changed. The worse part is that someone else holds your fate in their hands interpreting a fuzzy science, and what they say determines your future, kind of like the IRS (g).

Zannan said:

My MC takes a lie detector test to prove he didn't murder his cousin.
Even though he's telling the truth, he fails the lie detector test since he's nervous since he could be executed and angry his cousin's murderer is framing him.
What's the procedure for a lie detector test?
After he fails the test do the cops escort him out?

Click to expand...

One is free to go after a polygraph test. they don't prove anything. It's a one-way convenience which the participant can only hope to attest to their innocence. It cannot prove guilt, just discomfort on certain questions.

Sorry I am responding late, I don't post much anymore. The information you got is very good. But I am one who experienced a polygraph which implied I "was concerned" on some target questions.

It is important to stress the difference between corporate (my situation) and law enforcement professionals.

Corporate has a much lower standard and it's more of an interrogation sometimes than a structured study. Sometimes, they can be influenced by the client to lean harder on some.

LE is very structured if they want to try to present it as companion evidence. Much of the time it's an intimidation device in a modern witch hunt. Sometimes, they just want to know for themselves if they are pursuing the right suspect. Other times, they might do it by the book in some stated to present it as evidence.

One of the tactics used is certain honor-phrases like "what have you got to hide"? "If you're innocent, you won't mind taking a lie detector test" intentionally not referring to it as a Polygraph.

Because I am in certain professions and situations, I now have had many polygraphs and learned how to respond. I didn't do well in several but I can explain. I won't waste time here.

In my situation, I was very young working as a Warehouse Manager at GranJewel, a collaboration of W. T. Grants and JewelCor. One nite I caught the camera sales person escorting a customer out the door. We always checked receipts for floor sales and he vouched for him. But I asked to see it and it read 00.00 on the total line. I stopped the cameras from going out and made the employee come to the break room. we were pretty good friends so I offered to let him tell the Manager what he did before I did; but I told him I would give him until 10 AM to do it the next day. At 9:30 the next day, I watched him go into the Manager's office and spend some time. I was then called in and told to go take a polygraph because my "friend" told the Manager HE caught ME!

I was very angry and certainly showed. The method used on me was the above-referenced intimidation tactic. When the polygraph came out and accused me of trying to steal the cameras, I got up and smashed their machine on the ground. I was fired for damaging the equipment, not stealing.
Remember, I was only about 20 at the time and had a short fuse.
I was fired the next day and the person I caught kept his job.

Ask me what I think about polygraph tests.

Once one is stigmatized it can be damaging but one can use the history of repeated "failures" to prove, they simply don't work on you. I have written proof they simply don't work on me and I never suffered from future work or even working with organizations with high security clearance.


I am not really answering a question, I am just sharing an experience related to the OP.

As mentioned a polygraph/physiograph cannot be used to prove or disprove guilt. It may make the police really focus on looking for court admissible evidence, but that is all. The reason being that false positives are not uncommon, and only a very inexperienced detective is likely to think otherwise.

Back in the day I took my D class physiograph administrator test and they made it extremely clear to us that is measures stress, not guilt.