What device is commonly used to detect lies by measuring several physiological responses?

• A. Lie Detector
• B. Polygraph
• C. Plethysmograph
• D. Electroencephalograph

Answer: (B)

Detecting deception with a device hinges on monitoring physiological responses that tend to change when someone lies. The polygraph is the instrument designed to do this by recording several bodily signals at once—such as heart rate and blood pressure, breathing, and skin conductance—while a person answers questions. By comparing responses to relevant questions with baseline or control questions, examiners look for arousal patterns thought to accompany deception. This makes the polygraph the best answer because it is specifically built to collect multiple physiological channels in a single test, whereas a plethysmograph focuses on blood flow in tissue, an electroencephalograph tracks brain activity, and the generic term lie detector refers to various methods rather than a standardized device. Keep in mind that polygraph results are controversial and not universally accepted as definitive indicators of truth or deception.