Polygraph Test Must-Know Do's and Don'ts (2024)

Maybe it’s for a job application, or your partner asked you to take one to prove your innocence. Whatever the reason, polygraph tests are stressful experiences. However, going in prepared can help ease your nerves and ensure accurate results. Follow these do’s and don’ts when taking a polygraph test:


Before the Test

A polygraph examination screen and an examinee in the background.

Do get a good night’s sleep

Arriving well-rested will help you stay focused and calm during the lengthy exam. Aim for 7-9 hours of shut-eye the night before your test. Avoid caffeine and nicotine close to bedtime, as these can disrupt sleep.


Do have a light meal

Eat a light, protein-rich breakfast or lunch before the test. Going in hungry can make you feel weak, distracted, or irritable. A grumbling stomach can also interfere with results. Stick to easy-to-digest foods like eggs, yogurt, oatmeal, or a peanut butter sandwich. Avoid heavy, fatty, or sugary foods that can cause indigestion.


Do dress comfortably

Wear loose, comfortable clothing that allows for polygraph instrument wires. Avoid noisy accessories like jangly jewelry or rustling fabrics that could distract you or interfere with recordings. Dress in layers to adjust for warm or cool exam room temperatures.


Do disclose health conditions

Inform the examiner ahead of time if you have any medical issues like heart disease, breathing problems, or take medications that affect heart rate, blood pressure, or anxiety. These can highly influence polygraph results if unreported.


Don’t consume intoxicants

Avoid alcohol, recreational or prescription drugs, and even some over-the-counter medications before your test. Intoxicants impact physiological responses and brain function, invalidating test results.


Don’t overthink it

Worrying excessively about the test can spur anxiety that skews results. Distract yourself beforehand with positive activities like exercising, meditating, or enjoying hobbies. Don’t obsess over your honesty or controlling reactions.


During the Test

An examinee is attached to the lie detector machine while the examiner observes the results.

Do answer honestly

Lying will likely get caught by the polygraph. Answer all questions honestly and directly to achieve accurate test results. Avoid overexplaining or making excuses. Keep responses brief but with important details.


Do stay still

Avoid excess movement during the exam, which can disturb instrument sensors. Sit upright without crossing arms or legs. Keep both feet flat on the floor. Remain motionless during questioning. Nod or verbally reply to questions rather than gesturing.


Do breathe regularly

Concentrate on taking steady, even breaths. Don’t hold your breath, pant, gulp air, or breathe rapidly, as this affects blood pressure and heart rate readings. Inhale for 5 counts, exhale for 5 counts.


Don’t tense muscles

Relax muscles completely rather than tensing up. Tensing distorts physiological responses, impacting test accuracy. Let arms dangle loosely, legs rest naturally, jaw hang slack.


Don’t ask about questions

Don’t inquire about the next question or when the test will end. This borders on interfering with the exam. Just focus on answering questions candidly as they come.


After the Test

Do review results calmly

Avoid overreacting to test outcomes. Polygraph results aren’t foolproof. Listen calmly as the examiner shares whether you passed or failed. Ask polite questions about the readings if anything seems unclear.


Do get a second opinion

If you fail the test, request a second polygraph exam for confirmation. Testing errors happen occasionally. Verify results by taking another test soon after the first.


Don’t make accusations

Don’t accuse the examiner of botching the test if unhappy with results. That risks looking defensive and dishonest. Politely emphasize you know the findings to be mistaken and want a retest.


Don’t celebrate openly

If you pass, don’t gloat, pump your fist, or shout with joy. Remain professional and thank the examiner respectfully. Overcelebrating makes it seem like you lied but somehow fooled the test.


Do send a thank you

Follow up with a short thank you note to the examiner. This builds good will in case you need their polygraph services again down the road. Briefly express appreciation for their time and expertise.


Choosing an Examiner

A Man Appealing A Failed Or Inconclusive lie detector Result

Select an experienced, reputable examiner to ensure accurate, fair test results.

Do verify qualifications

Ensure the examiner underwent extensive accredited training and regularly completes continuing education. They should have certification from the American Polygraph Association.


Do check credentials

Look for lengthy experience conducting polygraph tests, such as 5+ years. Expertise with specific types of exams (e.g. forensic, federal) is ideal. An ex-law enforcement or government background is a plus.


Do request referrals

Ask the examiner for names of previous clients you can contact for references on their professionalism, testing procedures, and integrity. Speaking to referrals provides first-hand insights.


Don’t rely on cost

Avoid choosing an examiner solely based on low fees. This tempts underqualified individuals to cut corners that compromise accuracies. Expect to pay $300-$500 for a reputable examiner.


Don’t disregard reviews

Check independent online reviews of the examiner’s business. Numerous negative reviews or professional complaints should raise red flags on service quality.


Polygraph Test Settings

The polygraph test environment room (chair, computer, table, sensors, and devices).

Polygraph testing facilities impact comfort and focus during the exam.

Do opt for a private environment

Take the test in a secure, indoor location with minimal distractions. Home and mobile exams are risky due to interruptions. Professional testing centers are ideal for privacy.


Do request monitoring

For sensitive tests, have an observer like a lawyer monitor from another room. This ensures proper procedures are followed if issues later arise.


Don’t take it at home

Avoid polygraphs at private residences. Too many interruptions and comforts of home can interfere with results. It also looks suspicious if you fail.


Don’t allow unauthorized attendees

Refuse to take the test if more than the necessary examiner and monitor are present. Extra attendees raise risks of distractions or intimidation tactics.


Polygraph Test Questions

Test questions must be straightforward and relevant to produce valid results.

Do insist on simple wording

If a question is complex or confusing, politely ask for clarification or rephrasing. Keep questions brief, direct, and free of legal jargon.


Do object to vague questions

Raise concerns if questions are overly broad or vague. Respond to specifics only to prevent misleading answers. Overly general questions allow misinterpretations.


Do decline irrelevant questions

Politely refuse to answer overly personal or irrelevant questions. For employment exams, questions should relate directly to job qualifications. In legal cases, they should pertain to the investigation.


Don’t ramble

When asked an open-ended question, respond with concise, factual statements rather than meandering stories. Rambling makes it harder to detect truthfulness.


Don’t joke around

Remain serious when answering all questions. Humor and sarcasm are inappropriate during polygraphs and make you appear dishonest. Give straight, earnest replies.


Pre-Test Interviews

a note that reads, "Lie Detector Test".

Pre-test interviews prepare you for procedures and question topics.

Do answer background questions

Provide accurate details when asked about your work experience, health history, relationships, education, and other background. This helps contextualize your responses.


Do take notes

Ask permission to take written notes on the testing process, question types, your rights, and other key details covered. Refer back to ensure proper procedures.


Do voice concerns

Speak up if the examiner refuses to explain procedures, rushes the interview, or asks objectionable questions. This protects your rights.


Don’t get defensive

If asked confrontational questions, don’t get defensive or refuse to respond. Calmly provide honest, thorough answers to demonstrate you have nothing to hide.


Don’t make small talk

Avoid trying to chat casually with the examiner. Remain focused on the task at hand. Save non-essential questions and comments for pre or post-test.



A letter claiming that the polygraph was "passed".

With proper preparation, honesty, and an experienced examiner, polygraph tests can reliably assess truthfulness. Avoid common mistakes like poor sleep, tense muscles, and defensiveness. Focus on straightforward, pertinent questions asked in a professional environment. Stick to the do’s and don’ts outlined here to establish trust in your test results, whether passing or failing. With confidence and cooperation, the polygraph exam can provide clarity rather than confusion.


Can constantly shifting in my seat affect test results?
Yes, excessive movements can interfere with recording accurate physiological responses. Remain still.
Polygraph instruments don’t cause pain beyond minor discomfort from blood pressure cuffs or fingertips sensors.
You can refuse requests from friends or family. But employers and law enforcement can, in some cases, require polygraphs.
Inform the examiner if you need a restroom break. Taking a brief break typically won’t affect results.
It’s best to avoid heavy meals within 2-3 hours of your test. However, a very light snack 1 hour before is fine.
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