How To Beat A Lie Detector Test

Most scientists now agree that polygraph "testing" is junk science. In fact, John Larson, one of the pioneers of polygraphic lie detection, says "I'm sorry I ever had any part in its development." The test is valued by governments and others because it is useful for getting damaging admissions from people, especially those who don't know that the test is a sham.

Unfortunately, the test is actually biased against the truthful. This is because the more honestly one answers the "control" questions, the more likely one is to fail. Meanwhile, hardened criminals have proven they can lie throughout the test without detection.

Polygraph 101

The basic idea is this: The polygrapher asks some simple questions in order to get your "baseline responses." These are questions to which the operator knows (or assumes) the truthful answer. Meanwhile the device measures blood pressure, heart, breathing and perspiration rates.

Then you are asked "control" questions and "relevant" questions, such as,"Are you involved in espionage?" or "Did you take John's watch?" Your responses are compared to your control question responses, to determine if your answer is honest or a lie.  They will tell you that you should answer all questions honestly, but they don't actually want this to happen. In fact, they will often ask control questions that they assume you will answer with a lie. This could be something like "Have you ever lied when in trouble?" They may mention that someone who would do such a thing is suspect, thus encouraging you to lie, so they can see your response.

Operators use this kind of trickery as a standard part of the testing procedure. They also have to use their own judgment. If they think you are dishonest, they may interpret the results differently. Even if they don't do this, they may push harder to find questions that give the result they want. Whether this is conscious or not, it shows how unscientific the whole procedure can be.

In fact, there isn't even agreement among believers in the polygraph as to why it works. There are three common theories. The first is that a subject reacts when questions that strike sensitive areas, whether he is telling the truth or not. This theory would indicate that your nervousness (natural under the circumstances, right) might be taken as dishonesty.

The second theory is the theory of conflict. It supposes that a measurable physiologic disturbance takes place when a subject is caught between a habitual inclination to tell the truth and a strong desire not to admit to certain actions of facts. Some researchers think that if this concept is valid, it is only when conflict is intense. Of course habitual liars may be measured as honest in this case.

The most accepted theory is the threat-of-punishment theory. It says that a large physiologic response accompanies lying because a subject fears consequences for failing to deceive the operator. In other words, a subjects own fear of failing is what causes the response. The problem that many researchers note is that one who does not fear the results of his failure should not produce measurable responses.

"[The CIA's] reliance on the polygraph is truly insane." former CIA
Director John M. Deutch

"...the use of this highly flawed instrument should be radically curtailed."
former CIA Director R. James Woolsey

How To Beat It

Don't Take It

There is little that taking the test can do to help you, and a lot that can hurt you. In criminal matters, just refuse. In cases of pre-employment screening, you may have to take the test to get the job. There is one technique that has been used to have the test waived, even for positions in the Department of Defense. This involves letting the operator know that you understand how the test works.

R.C. Davis, in "Physiological Responses as a Means of Evaluating
Information" found that if a subject "knows that changes in breathing will disturb all physiologic variables under control of the autonomic division of the nervous system, and possibly even some others, a certain amount of cooperation or a certain degree of ignorance is required for lie detection by physiologic methods to work."

Because of this, you will generally not be considered an appropriate subject if you know too much about the test. How do you convince the operator of this? Try the following: go to the web site http://antipolygraph.org and download the book "The Lie Behind The Lie Detector." Read it, and keep a printed copy handy.

When you arrive for the test, tell the operator what you know about the test, and show him the book to prove it. Then explain that because of this, you are not a suitable candidate for polygraph testing. He should agree. Be careful though, as he may angrily decide that you still should take the test, and may even decide to fail you regardless of results.

If You Take It

If you decide to take a polygraph test, insist that your lawyer be present through the entire examination. Also, refuse to sign any papers, such as those saying the results will be admissible in court, or used for other purposes. Insist that the entire examination be videotaped, and that you get a copy as soon as it is done. (At least have it audio taped.) Finally, refuse any post-test interrogation.

Behavioral Countermeasures

Look and act innocent. Be polite to the examiner. He has to use his judgment to decide how to interpret the results, as well as how hard to push in certain questions. You want him to like you and assume you are innocent from the start, so he doesn't try too hard to prove your guilt.

During the test he may stop to ask you why you seem to be responding strongly to a certain question - especially a control question, if you are applying physiological countermeasures. Have a seemingly spontaneous answer ready. For example, hesitate, look confused and say, "I guess I always feel guilty when I am asked about things. My mother was a very suspicious person, and used to blame me for so many things that I felt like I had really done them."

Physiological Countermeasures

The idea behind physiological countermeasures is to have stronger physiological responses to "control" questions, so that the responses when you answer relevant questions will seem normal when compared to them. So the first thing you need to know is how to tell the "control" questions from the other questions. You can usually tell them by their vagueness, as in "Did you ever cheat in school?"

When you identify a question as a control question, you want to have a measurable increase in your response to it. The primary ways to do this are by using your breathing and your heart rate. Train yourself to breath comfortably at the same rate throughout the interview (until the devices are removed from your body).

During the test, use one or both of the following
two countermeasures. 

1.      Breathing responses:

After answering a control question, do one of the following:
a. Breath more slowly for 5 to 15 seconds, then resume normal breathing
before the next question.
b. Hold your breath for 4 to 5 seconds, then resume normal breathing before
the next question.
c. Exhale more slowly than you inhale for 5 to 15 seconds, then resume
normal breathing before the next question.
d. Take several shallow breaths, then resume normal breathing before the
next question.

2.      Heart rate responses:

After answering a control question, do one of the following:
a. Quickly bite the side of your tongue hard enough to hurt a little. This will
get your heart rate to speed up. Practice this one in front of a mirror, so you
aren't obvious when you do it.
b. Use your imagination to speed up your heart. Quickly think of a car crash,
a knife going into you, or anything that will provoke a fear response.
There is no evidence to show that polygraph operators can detect these
countermeasures. If you combine behavioral techniques with well-executed
physiological techniques, the operator will be fooled, and have no reason to
think you are lying.