Psychophysiology is the scientific study of the interrelationships between, physiological and psychological aspects of the human mind & behaviour. Research in Psychophysiology, typically includes psychological independent variables and physiological dependent variables. Such variables include, hemodynamic and electromagnetic brain imaging, alongside peripheral measures such as respiratory sinus arrhythmia (RSA) i.e.,  heart rate variability in synchrony with respiration,  as well as electromyography, pupillary reactions (pupillography).