Can You Beat a Lie Detector Test?
Some People Think They Can
Pass a Polygraph Test by Cheating
In the UK we expect to see one in ten clients try to cheat and perform countermeasures to try to pass a polygraph test. In the pre-test interview I often cover the common things we see and explain just how easy they are for an experienced examiner to notice.
- Breathing Manipulation
The most obvious to spot, as there is always a pattern.
It’s quite normal for candidates trying this to still spectacularly fail a test, even when we have identified to them the irregular breathing patterns
- Blood Pressure Manipulation
We have candidates that tense up, to trying manipulate their blood pressure. When asked about it they may insist they were relaxed, but these attempts are painfully obvious. After stopping the test and explaining what purposeful non co-operation would mean, they will stop, or we will dis-continue the testing.
The most the most extreme countermeasure, generally, is taking drugs. Being too relaxed, to the point that the charts come out flat, is very obvious. We always ask a lot of questions and have the subject purposely lie. When there is no baseline reaction to compare with, something is obviously wrong. We’ve seen subjects have zero reaction no matter the question, which does not allow us to conduct a test. This is certainly not passing.
Purposeful Non Co-Operation…or Not?
It is easy for the cynic in us, due to the nature of our business, to expects everyone causing a false reaction is trying to cheat. However, it’s also is true that innocent people may do something we think are countermeasures.
One example was observed recently when testing someone with a resting heart rate of 140 beats per minute. It turned out they had consumed four cups of coffee pre-test, which was normal for him at that time of the day. Without knowing this it would certainly be considered purposeful. Of course they were so nervous and shaky we could not conduct the test in that situation and they had to reschedule. This is one reason we always interview the subjects and explain these things. Pre-testing is a majority of the examination and the tricks people try just do not work. Sometimes people just do the wrong thing without intent…but the test will still be stopped.
We are often asked if there things someone can do to pass a polygraph test and we answer potentially yes, but they are all very obvious and easy to spot by a properly trained and experienced examiner.
The majority of what the TV or the internet teaches you is very wrong or out of date for the polygraph industry. The education, experiences and the advances in the equipment used today is not the polygraph of the old black and white detective movie.
There is only one way to pass a Lie Detector Test…just one…TELL THE TRUTH!