Professional in Human Resources (PHR) Practice Exam

A polygraph test measures physiological responses that are believed to be associated with deception, specifically respiration, blood pressure, and perspiration during questioning. The underlying assumption is that when a person is being untruthful, they may experience increased stress, which manifests in physical changes measurable by the polygraph.

During a polygraph examination, sensors are attached to the individual to monitor these physiological indicators as the test subject answers questions. If significant variations are noted in these measurements when the subject responds to relevant questions, it may suggest that the person is experiencing heightened emotional arousal, which could indicate deception.

The other options do not accurately represent what a polygraph measures. Brain activity is not directly assessed by a polygraph. Emotional responses to visual stimuli are not evaluated in this context. Muscle tension is also not captured as primary measurable data in the standard procedure of a polygraph examination. Thus, option B is correct in framing the polygraph's focus on the key physiological responses relevant to the testing process.