Biofeedback is based on the measurement of several different physiological parameters. These parameters are:
- skin conductance level as a measure of the activity of the sympathetic branch of the autonomic nervous system
- skin temperature (usually finger temperature) as a measure of the skin/finger perfusion
- heart rate as a measure of cardiac activity
- pulse volume amplitude as a measure of blood flow
- respiration rate and respiratory amplitude as measures of breathing activity
- neuromuscular activity (EMG) as a measure of muscular tension and/or activity