A polygraph for infidelity may come up in divorce settlements, particularly if a prenuptial agreement specifies infidelity as grounds for divorce. Additionally, some states consider infidelity a punishable crime and may request a polygraph as proof of guilt or innocence. The test would be conducted by a certified polygraph administrator, though desired questions may be submitted for the examiner to ask during the polygraph. The test would consist of questions that the examinee would respond to with yes or no while the polygraph machine would measure physiological changes such as heart rate and skin conductance.
Prepare the questions in advance to keep the polygraph moving and avoid distracting the examinee or making him more nervous. All questions should be "yes" or "no" questions for a polygraph. Examples of infidelity questions could be "Are you currently having an affair?" "Have you ever been unfaithful to your spouse?" or "Have you thought about having an affair?" Poor choices for polygraph questions are questions that cannot be answered with a simple "yes" or "no" such as "Who was the affair with?" or "How often did you meet?"
Establish a baseline at the beginning of the polygraph exam. The baseline should consist of several questions that will elicit truthful responses, whether the truth is "yes" or "no." The examinee should be prompted to lie for several obvious questions. An example of an obvious lie would be the examinee answering "yes" to "Are you wearing a green shirt today?" when he is in fact wearing a white shirt.
Speak in a calm, clear voice when reading the questions. Follow the list of prepared questions. While reading and listening to the examinee's responses, avoid making comments or noises that may make her more nervous. The only sounds made by the polygraph examiner should be the reading of the questions calmly and the occasional marking of a pen on the polygraph printout.
Stop the examinee if he begins to give an explanation or additional information other than a "yes" or "no" response during the polygraph. Explain in advance that only "yes" and "no" responses are valid during a polygraph. Encourage only straight "yes" or "no" responses and then move on to the next question.
Under the Employee Polygraph Protection Act, an examiner may not ask questions during a polygraph exam that involve sexual preferences or sexual activities, among other restricted topics. Therefore, a polygraph testing for infidelity could not be conducted on an employee or for work-related reasons.
A polygraph is only effective with yes-no questions; questions asked that require full responses, or if full responses are provided, they will not enhance or improve polygraph accuracy and can prolong the test or render it useless, such as if the examinee refuses to respond only with yes or no.
During the baseline questioning, often the polygraph administrator will ask whether the examinee has taken any sedatives or other drugs prior to the exam. Sedatives or drugs would make the polygraph exam less accurate due to the changes in the examinee's physiological state.