Which of the following is a limitation of the polygraph method for lie detection?

• A. Polygraph results are always admissible in court.
• B. Polygraph tests are unaffected by individual differences in physiological responses.
• C. The polygraph cannot reliably distinguish between anxiety and deception.
• D. The polygraph measures brain activity directly.

Answer: (C)

Verified step by step guidance

1. Understand what a polygraph measures: it records physiological responses such as heart rate, blood pressure, respiration, and skin conductivity, which can be influenced by emotional states.
2. Recognize that the polygraph does not measure brain activity directly; instead, it infers deception based on physiological changes that may accompany lying.
3. Consider that individual differences in physiological responses can affect polygraph results, meaning not everyone reacts the same way under stress or deception.
4. Analyze the limitation that the polygraph cannot reliably distinguish between anxiety caused by lying and anxiety caused by other factors, such as nervousness or fear.
5. Evaluate the admissibility of polygraph results in court, noting that they are not always accepted as reliable evidence due to these limitations.