How are polygraph examinations used in personnel security?

In the context of personnel security, polygraph examinations are utilized as a screening or vetting tool to assess the trustworthiness of individuals during the recruitment process. Employers use these examinations to help predict future behavior based on an individual's past actions, aiming to select candidates with a high prognosis for loyalty and honesty.1

The examination functions by measuring involuntary physiological responses—such as blood pressure, pulse rate, respiratory rate, and perspiration—while the subject answers a series of questions. By comparing reactions to control questions with those to relevant inquiries, examiners attempt to identify potential deception.234

However, the use of polygraphs in personnel security is subject to significant debate. Critics and many experts argue that the instrument is unreliable because it measures physiological arousal—which can be triggered by nervousness or anxiety—rather than definitively detecting lies. Because these responses can be influenced by factors other than deception, and because results can potentially be manipulated, the polygraph is generally not considered a foolproof method for determining an individual's integrity. Consequently, it is typically used as one component of a broader security program rather than as a definitive measure of a person's character.2431