The polygraph is a computer-based machine that measures which physiological signals during questioning?

The polygraph is a computer-based machine that measures which physiological signals during questioning?

• A. Blood pressure, electrodermal activity, and respiratory changes
• B. Heart rate and brain waves only
• C. Body temperature and muscle activity
• D. Vocal pitch and eye movements

Answer: (A)

The main idea is that a polygraph monitors autonomic arousal through multiple physiological signals, not brain activity. The device typically records respiration (breathing changes), electrodermal activity (skin conductance), and cardiovascular activity such as blood pressure and pulse. These signals change with sympathetic nervous system activation, which can occur when a person experiences cognitive load or emotional responses during deception. This combination—blood pressure, electrodermal activity, and respiratory changes—is what the polygraph is designed to track, making it the best choice. Other options miss key signals the polygraph uses (for example, brain waves aren’t measured by a standard polygraph, and vocal pitch, eye movements, body temperature, and muscle activity aren’t primary polygraph signals).

The main idea is that a polygraph monitors autonomic arousal through multiple physiological signals, not brain activity. The device typically records respiration (breathing changes), electrodermal activity (skin conductance), and cardiovascular activity such as blood pressure and pulse. These signals change with sympathetic nervous system activation, which can occur when a person experiences cognitive load or emotional responses during deception.

This combination—blood pressure, electrodermal activity, and respiratory changes—is what the polygraph is designed to track, making it the best choice. Other options miss key signals the polygraph uses (for example, brain waves aren’t measured by a standard polygraph, and vocal pitch, eye movements, body temperature, and muscle activity aren’t primary polygraph signals).