Thursday, December 02, 2010

FBI Citizen’s Academy Week 6 - Lie Detector


The last part of week 6’s session was on the lie detector. The first thing the agent addressed was that you could not do a demonstration of the lie detector, because there are no consequences to the questions asked, so the physical reactions aren’t there.

There are three parts to the lie detector, or three parts to the screen at least. At the top is the record of the leads on fingers, which collect sweat. This has a stable base line, then a squirt when there is a reaction to a question.

There are two belts made of tubes which circle the chest and measure breathing. The lines for these look like hills when there is a change.

Finally there is a blood pressure cuff.

The examiner looks at three things: consistency, time line, and significance.
Is the subject’s response consistent? The same questions will be asked several times, in a random sequence. If the subject responds the same way to the question no matter when it is given, there is significance to the response.

What is the time line of the response? Does it come at an appropriate time with regard to the asking of the question? (Often the response will come a little before person actually speaks, because the person is anticipating lying, and that causes the physical response.)

Is the response significant? Is there enough of a change in the subject’s response to merit calling it a physical reaction?

If you volunteer to take a lie detector test, for example in applying for a job, and you test positive for a crime, they will prosecute you. In one case, an applicant for a job with the Border Patrol admitted to child porn during the exam and was arrested.

Who doesn’t test well?
  • People who are not focused-- for example due to drugs and/or alcohol. If you aren’t paying attention to the questions, your body won’t react to them.
  • People who can’t pay attention-- for example, those with ADD-- for the same reason.
  • If there is an outside issue that is more important to the subject. For example, if a suspect is being interviewed about a house break-in but actually committed a murder, he won’t react to questions about the break-in because they are less important than the murder.

There are also a couple of medications that mess with results. And of course he wouldn’t tell us which ones!

The most important part of the lie detector exam, he said, is the interview with the subject and the ability to establish a rapport. If the suspect does test positive for the crime, he will then initiate a “direct, positive confrontation.” He won’t ask if the subject did it-- he will move forward saying that he did.

Then he turns to RPM: rationalization, projection, and minimization.

He will rationalize what the subject did. Anyone would have done that thing, for example. Of course, you take a guy who needs money, and you present him with the opportunity to steal something. That’s rationalization.

Then he projects the blame onto someone else. It was really the victim’s fault, for having all that expensive stuff and not having good security.

Finally he will minimize the seriousness of the crime. At least you didn’t kill anyone, right? All you did was steal some stuff. It’s just stuff. And now you need to own up to it so you can move forward.

This encourages the suspect to admit guilt.

He doesn’t discuss the legal penalties when minimizing-- that’s not his job and he can’t make those kind of statements. And he never tapes these interviews, because he wouldn’t want a jury to hear an FBI agent saying some of these things, because out of context they would sound inappropriate.

I feel like I understand the lie detector process a lot better now, and I’d feel comfortable putting at least part of this into a book. I’m already having a police character discuss the RPM because I think it’s fascinating and a good way to get a fictional criminal to confess.