Under Arrest - P is for Polygraph


Welcome back to A-Z. Today's letter is P, and it is for polygraph tests. Their effectivity is controversial, and courts acknowledge this by not admitting polygraph test results as evidence. Still they're widely and somewhat enthusiasticly used - if for nothing else than to intimidate suspects.

In my Interrogation post I talked a little bit about CBI Agent Tammy Lee and what a fabulous job she did with Chris Watts. 


If you're interested in these kinds of things, you may take the time to watch the videos: 

After the 50 minutes' mark Tammy starts explaining to Chris what the polygraph questions are going to be, and she literally preps him in detail. 

I didn't know this. I thought, part of the "appeal" of the lie detector test is that you don't know what they're going to ask you and you'll get hit by the surprise factor.

She is going to ask "did you physically cause Shanann's disappearance?" What might possible answers be? Chris plays innocent and suggests things he knows from movies or what awful things you read that evil people did: hire a hitman, use a weapon like a gun or a knife, kidnap, smother or poison the victim,...

She goes on explaining why she will only ask about the physical involvement because obviously if you tell someone you don't love them anymore and you want to separate, you may somehow emotionally  have caused the person to leave because their feelings were hurt and they took off, but it didn't mean you did something that physically hurt (or killed) them. 

"Are you lying about the last time you saw her?"
No - she was in bed, alive. 

"Do you know where Shanann is now?"
I do not.
They discuss that if Chris had killed and dumped her, he would obviously have seen her at the location where he left her dead body.

There are going to be questions on the test that he is actually supposed to lie about because she wants to see his body's reaction when he lies. Those questions are:

  • Before 2018 did you ever lose your temper with someone you cared about? Think about this actual situation!
  • Before 2018 did you ever say something out of anger to a loved one? Again visualize the situation.
  • Before 2018 did you ever want to hurt someone (like punch 'em in their face because they pissed you off) to get even with them? Bring up pictures in your mind about this  situation.

In order to also create a baseline for when you're totally telling the truth, there are some "Known truth questions":
  • Is your first name Christopher?
  • Were you born in 1985?
  • Are you know in state of Colorado?
  • Are you now sitting down?
  • Are there white walls in this room?
  • Do you understand I'm only asking you the questions we have discussed?
Chris gets hooked up on the instruments (I'll talk about them below), and they do a portion of the test they call the "directive lie practice test":

Tammy shows him a chart with numbers, and he has to write down the number three on the clipboard. She proceeds to ask him if he wrote every number, and he is supposed to lie about having written the number three. 
He tries to be funny and show how truthful he is, so he goes "nnn-yes, I mean no." Haha.
Now things are getting serious. Here are the instructions: don't move as in sit still and don't fidget! No sniffling, no sneezing, no nothing. If I tell you to be still don't go "ohmygosh, I'm sorry." Just be still. Don't look at me, look at the clipboard. And remember, just yes or no.

After this part is done, she goes all cheery on him. "You did great, you remembered to lie and everything, that was awesome!"

Chris chuckles nervously. He'll have to remember to lie some more in the main portion of the test!!

"So obviously you're a really bad liar, have people told you that before? Like on your face and everything, I can see a significant reaction when you lie, so thank you for being a horrible liar! So on the real test if you lie about your wife that'll be ten times more amplified."

Ohmygosh, now would be a good time to come clean, Chris!

They go ahead with the actual test, and she tells him there will be at least three runs, and if he's moving or something else disrupts the readings they can go up to five times.

Tammy is really looking forward to this:

"The coolest thing is that right now there's only one person in the room who knows the truth - in about five minutes there's gonna be two. Any questions before we start?"

Tell her!! Tell her now, you fool!

At 42:22 the actual test begins:

After the first run she asks if he has any issues with the "hot" questions, (because obviously she can already clearly see he's not telling the truth), and she repeats everyone of them:
  • Regarding Shanann's disappearance, do you intend to answer all my questions truthfully?
  • Did you physically cause Shanann's disappearance?
  • Are you lying about the last time you saw Shanann?
  • Do you know where Shanann is now?

But he's still "I'm fine. All good."

So you know the rest. They present him with the results "you failed" and Chris still tries to be like "that can't be, I didn't do anything, I swear." 

After speaking to his Dad he at least confessed to killing his wife. 

So far so good.

Now, we all want to know: how does the technical part of detecting lies work?

They hook you up to the following instruments (Source: The Fundamentals of Lie Detector Testing): 

The polygrapher scores the test by comparing physiological responses (breathing, blood pressure, heart and perspiration rates) to probable-lie control questions (example "Before 2018 did you ever lose your temper with someone you cared about?") with reactions to relevant questions (example "Do you know where Shanann is now?")

If the former actions are greater, the suspect passes; if the latter are greater, he fails. If the reactions to both questions are the same, the result is called inconclusive. 

The irrelevant questions (example "is your first name Christopher?") help to provide a baseline for your regular calm self - however they are not scored at all and just serve as buffers between relevant and control questions. 

There are all kinds of articles and videos out there that tell you how to "ace" a lie detector test, but guys, I don't know, if you're a regular person who committed a once in a lifetime crime and try to cover it up, how can you play it that cool? 

Now I like to think if you're either a full blown psychopath (and we'll talk about them and how sociopaths are different next week) or a trained professional you might beat the test:

There was this guy Aldrich Ames, a CIA counterintelligence officer who committed espionage against the U.S. by spying for the KGB. He passed two polygraphs. I am not overly surprised though, because isn't a government agent supposed to be great at lying and deceiving people?

As I said in the beginning, polygraph tests are controversial. Obviously they can cause false fails and stuff. If you're a defense lawyer like to one who worked for Scott Peterson you are going to have your client refuse to take the test, claiming that even if you pass it, the polygrapher will tell you it was inconclusive.

Shouldn't an innocent person do everything to cooperate? If you have nothing to hide, can't you go answer a few questions?

I really don't know - what do you think?

Image by Gerd Altmann from Pixabay


  1. Polygraphs have always fascinated and yet terrified me. I can break into a sweat just thinking about them. LOL!

    DB McNicol, author
    A to Z Microfiction: Parachute

  2. very descriptive post! thanks. have you see the american tv show about aldrich ames? "the assets" i think. it used to be on netflix but no longer (at least in US). i read he actually got some of his polygraphs wrong but he had befriended the reader so his answers were positively read.

    Joy at The Joyous Living

  3. I had no idea the tests were so long. But I guess they would have to be.

  4. Very interesting. I had to look up what he did. Horrible. I can't imagine him being able to just sit there and answer questions like that.

    Janet’s Smiles

  5. I never had the idea that these tests tale so long. Thanks for enlightening me

  6. Wow - that's interesting! The only thing is that I'm sure the stress of the situation would have an impact on me. I think they can add to a picture but should be relied on as the total picture!
    Wren x


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