Polygraph tests are used in a variety of situations. In addition to being a tool used by police investigating a crime, a person may be asked to take one during a pre-employment background check or during internal investigations where employee theft is being investigated.
It seems like an easy way to resolve doubts and prove your honesty, but it may end up causing you more problems.
The accuracy of lie detector tests
A lie detector test, also called a polygraph test, doesn’t determine if you are lying. Instead, it measures physiological responses like heart rate, blood pressure, respiration and skin conductivity while you answer a series of questions. By measuring these changes, it will be determined if you are being untruthful or deceptive.
However, there is doubt about the validity of polygraph results. Some research has shown that they are only accurate between 70-90% of the time. Many innocent people have been wrongfully convicted based on the results of these tests. Stress impacts people in different ways. Some people may experience heightened anxiety simply because they are being asked to take the test, even though they’re telling the truth. Conversely, people who are calm under pressure may not exhibit physiological changes, allowing them to trick the machine, even if they’re lying.
There are other reasons why a polygraph may give false readings, including:
- Environmental conditions during the examination, such as room temperature
- The suspect has a mental health disorder or is taking prescription drugs
- The examiner has an unconscious bias
- The examiner is inexperienced
If you are suspected of committing a crime and the police request you take a polygraph test, you have the right to decline. It is one of your constitutional rights. Instead, you should request the presence of someone who will ensure your rights are upheld.
