A simple way to cheat the polygraph is to deliberately distort your physiological readings when telling the truth, such as by biting your tongue, or imagining an embarrassing incident in the past.
Can you pass a polygraph test lying?
A polygraph test or lie detector test is designed to analyze physiological reactions to questions to determine whether or not a subject is being truthful. Fortunately for them, its not that hard to beat a lie detector test. The first step to passing the test is understanding how it works.
Can polygraph results be manipulated?
A lie detector, or polygraph, indicates physical changes that occur in response to questions. These changes include alterations in blood pressure, pulse rate and respiration that may occur when a person lies. In addition, Lykken said, a person can manipulate the outcome of a polygraph test to his advantage.