A polygraph examination isn’t a fail or pass issue like taking your GCEs at school. You won’t fail a lie detector test based on how knowledgeable or intelligent you are.
ANS and consciousness
Polygraph technology functions by measuring physiological alterations in the human body including changes in breathing, pulse rate, blood pressure and perspiration. It records a subject’s ANS (autonomic nervous system) responses when questions are being asked. The ANS controls bodily functions but you are not conscious of it. For example, you are not usually consciously breathing or conscious of your heart beating but these functions will continue whether you are awake or asleep.
Dishonesty is indicated when the ANS goes into defensive mode repeatedly, reacting to a specific test statement or question. If the polygraph examiner concludes that deception is evident by this reaction to one or more questions, you will have ‘failed’ the test.
When deception is indicated it doesn’t necessarily mean you have lied. But constant research and test results have revealed that 90 to 95% of subjects with this type of reaction had lied. Or they had withheld relevant information related to what they were asked.
In the UK lie detector tests are mainly used
- In recruitment, to screen prospective candidates
- By private individuals who have been falsely accused of something
- By police to test the honesty of witnesses or suspects
- For monitoring criminal offenders when they are released on licence
- When cheating is suspected in a relationship
- In business when one or more employees are suspected of theft or fraud
Withholding vital information may cause an examiner to determine that you cannot be excluded as a suspect. You may well have told the truth but your ANS knows you are not divulging something that is highly relevant. Usually when a subject withholds information, it is because they don’t want to incriminate themselves. If you fail a lie detector test due to withholding information, and police are involved, the result will make them investigate you in more depth.
What you can do if you fail a lie detector test
You can confess, or if you withheld information divulge it. Alternatively if you feel the test was not administered properly you can take another test. Generally speaking honesty is the best policy because one way or the other polygraph examiners will find the truth.