For a polygraph, which measure is regarded as the most important indicator of stress?

In the context of a polygraph examination, heartbeats are considered a critical indicator of stress because they reflect the physiological response of the autonomic nervous system to perceived threats or anxiety. When a person experiences stress, their heart rate typically increases due to the body's "fight or flight" response. This reaction can be a response to the anxiety of being tested or the pressure of the questions being asked during the polygraph.

While other physiological measures, such as breathing patterns, galvanic skin response (which measures skin conductivity as a reaction to sweat), and perspiration can provide valuable data about an individual's emotional state, heart rate is often seen as the most direct indicator because of its clear association with stress. It can indicate immediate emotional changes and has a more pronounced and noticeable effect that can be quantitatively measured during a polygraph assessment, making it a focal point for examiners in interpreting results.