What is the purpose of a polygraph in an investigative setting?

The use of a polygraph in an investigative setting is primarily aimed at determining if the subject is lying. This tool measures physiological responses—such as heart rate, blood pressure, and respiration—that can indicate stress or deception when a person responds to questions. While polygraphs are not foolproof and their results can be subject to interpretation, they can provide valuable information in an investigation by pointing out discrepancies between the subject's physiological responses and their verbal answers.

The significance of this function lies in its ability to enhance the investigative process by potentially identifying areas where further inquiry is needed. It’s important to note that the results from a polygraph are often considered supplementary to interviews and other forms of evidence rather than definitive proof of truthfulness or deception. Consequently, the polygraph serves as a tool that can guide investigators in their strategy rather than a means of completely replacing traditional investigative methods, such as interviews or gathering evidence, which is why other options proposing its sole effectiveness or replacement for other processes do not accurately capture its role in the investigative framework.