Which statement about the polygraph is incorrect?

The statement that a polygraph test is conclusive is indeed misleading. While polygraph tests measure physiological responses such as heart rate, blood pressure, and galvanic skin response, these measurements do not directly indicate whether a person is telling the truth or lying. Instead, the results are interpreted by a trained examiner, who assesses the physiological reactions in relation to the questions asked during the test.

The nature of the polygraph is that it can provide indications of stress or anxiety that may accompany deception, but it is not an absolute measure of truthfulness. Various factors, such as the individual’s emotional state, the context of questioning, and even the examiner's techniques can all affect the test results. Consequently, the results should be considered as part of a broader investigative process, rather than as definitive proof of truth or deception. This is why the assertion that a polygraph test is conclusive is incorrect.