How to Prepare for a Polygraph Test

Polygraph Machine
••• Paul D. Waite: Flickr Creative Commons

The goal of a polygraph or lie detector test is to determine whether a person is telling the truth or lying when answering a series of questions. Polygraphs are controversial because many people believe they are not reliable. Polygraphs are used by law enforcement agencies and some employers. There are some steps you can take to prepare for a polygraph test. The best step you can take is to be prepared to tell the truth.

Schedule your appointment at the beginning of the day or right after lunch when you are still feeling fresh and alert. Do not schedule your appointment at the end of the day or at the end of the week, when you are feeling tired.

Get a good night's sleep. Don't stay up late watching television or reading. Get up on time in the morning to give yourself plenty of time to get ready without rushing.

Read More: How to Read a Polygraph Test

Eat breakfast if your appointment is in the morning. Eat lunch if your appointment is in the afternoon.

Follow your normal routine. Drink coffee if you are a coffee drinker. Take any prescribed medications. Coffee and medications will not affect the results of your polygraph test.

Plan for an exam that will take about 2 hours. This includes pre-test preparation to ensure you are comfortable with the questions asked.

Know your legal rights. An examiner should not ask questions about the following areas during an employment exam: religious beliefs, opinions regarding racial matters, political beliefs or affiliations, affiliations with or lawful activities related to unions, and sexual preference or activities.


  • Don't worry if you are nervous. A polygraph test does not measure nerves. It only measures whether you are telling the truth or not. During your polygraph, focus only on the question that has just been asked. Don't think about the previous question or about what kind of question might come next.

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