A polygraph exam, regardless of the purpose, is a physiological measurement tool used to determine truthfulness or deception. The examinee is connected to the polygraph machine in a way that heart rate, respiration and sweat gland activity are monitored. Sometimes with high-tech polygraphs, a voice analysis is also conducted. The polygraph examiner asks a series of test questions that allow him to establish the examinee's baseline for truthfulness. In other words, the baseline shows what the examinee's physiological responses look like when being truthful or deceptive. The baseline is an important step in a polygraph exam because many people experience a lot of anxiety in this situation and the physiological symptoms of anxiety can undermine the deception measurements. All questions are asked in a flat tone (no intonation or accenting of words) and all questions are responded to with either a "yes" or "no."
Submit to the polygraph as if it were nothing more than a standard interview. Refrain from taking any medication, drugs (prescription or illicit) or alcohol before the exam, as these can alter your physiological responses and will likely cause you to automatically fail the exam should the examiner detect the effects of drugs or alcohol. The best thing to consume before a polygraph exam is food; triggering digestion will override the physiological processes normally associated with anxiety. Answer all questions truthfully using only a "yes" or "no" and if unsure of a question ask for clarification.
Ask the polygraph examiner before leaving, but after the exam is complete, how you did. The goal of the polygraph is to detect deception, so regardless of your responses to the questions, as long as you gave truthful responses, you will not display signs of deception. In this case, the examiner will likely tell you there was "NDI" or "no deception indicated."
Relax and wait. If you were not deceptive in your exam, and have nothing to hide, then you have nothing to worry about. Your results will be revealed when the investigation or process is complete. Or when complete, you may inquire about your results if curious.
Work on relaxing for several days leading up to the polygraph exam. Engage in regular exercise, eat right, get plenty of sleep and try to avoid seeing the polygraph as a frightening situation. While most people can't control physiological responses effectively, you can reduce the potential for a false positive by staying calm and rational.
Taking a polygraph exam for a pre-employment screening or for a current employer can have different repercussions. For pre-employment screening, if you refuse a polygraph or fail one you will likely not be hired. For an employer, you may refuse without the risk of being fired but the refusal of a polygraph in conjunction with other evidence can support grounds for termination.