What measure would best assess sympathetic arousal in participants during a study?

• A. A. A measure of electrical conductivity of the skin
• B. B. A CT scan of the hindbrain
• C. C. A PET scan of the parietal cortex
• D. D. A measure of melatonin levels

Answer: (A)

The measure that best assesses sympathetic arousal in participants is the electrical conductivity of the skin. This is tied to the concept of skin conductance response (SCR), which reflects the activity of the sweat glands that are activated by the sympathetic nervous system. When individuals experience arousal—emotional or physiological—sympathetic activation leads to increased sweating, which in turn increases the skin's electrical conductivity. Thus, measuring changes in electrical conductivity of the skin provides a direct indication of sympathetic arousal and is commonly used in psychological research to assess emotional responses.

Other choices, while useful in their respective contexts, do not directly measure sympathetic arousal. Imaging techniques like CT and PET scans focus on anatomical and metabolic activity within the brain rather than capturing physiological responses linked to emotional states or stress. Measuring melatonin levels relates to circadian rhythms and sleep patterns, which do not directly correlate with the immediate sympathetic arousal associated with emotional or stress responses.