Autonomic Nervous System

The division of the nervous system that regulates involuntary physiological processes including heart rate, blood pressure, respiration, digestion, and stress responses. The ANS has two main branches: the sympathetic nervous system (activating "fight or flight" responses) and the parasympathetic nervous system (promoting "rest and digest" states). In affective computing and accessibility research, ANS activity is measured through physiological signals like heart rate variability, electrodermal activity, and skin temperature to objectively detect stress, arousal, and emotional states without relying on self-report.