Certified Protection Professional (CPP) Practice Exam

Which of the following statements about polygraphs is incorrect?

1. A polygraph test is conclusive

2. A polygraph measures truthfulness directly

3. A polygraph is used in criminal investigations

4. A polygraph test can be administered without consent

The correct answer is: A polygraph test is conclusive

A polygraph test is not conclusive, meaning its results can't definitively determine truthfulness or deception. While the test measures physiological responses such as heart rate, breathing, and galvanic skin response, these indicators can be influenced by various factors unrelated to truthfulness, such as anxiety, nervousness, or environmental stressors. This inherent uncertainty makes the results of a polygraph test more suggestive rather than definitive in determining whether someone is lying. In contrast, the other statements reflect facts. Polygraphs are indeed designed to be used in criminal investigations, serving as tools to gauge the veracity of a person's statements. They do not measure truthfulness directly; instead, they assess physiological reactions that are believed to correlate with truthfulness, albeit imperfectly. Additionally, ethical and legal standards typically require consent for administering a polygraph test, but lacking consent does not mean the test cannot be attempted, especially in certain contexts. However, the critical understanding is that the results themselves are not definitive, affirming that no conclusion can be reliably made from a polygraph test alone.