ABSTRACT
Modern stress research was born from the larger field of emotion theory and, after a brief sojourn, it is to here it has begun to return. Cannon suggested that events which provoked emotions can instigate the fight/flight response, thereby identifying the influence of psychology on biology. The link between physiological and psychological responses to external events is undeniable, and was given another dimension in S. Schachter's cognitive theory of emotion. Schachter's theory is sometimes referred to as the lability theory or the two-factor theory of emotion – the two factors being physiological arousal and cognitive appraisal. The sympathetic nervous system is that part of the central nervous system which is central to the fight/flight response and most directly involved in the emotions. Although the ancient roots of emotion theory are clearly psychological, modern theory in the area since the Enlightenment has been preoccupied with the biology of emotions and developed into a biological theory of stress.
