A polygraph is a device used to measure

A) depth of hypnosis.
B) individual action potentials.
C) emotional reactions.
D) memory.

Polygraph

An instrument that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions, purported to indicate truthfulness.

Action Potentials

Electrical impulses that travel along the axon of a neuron, allowing it to communicate with other neurons or muscles.