Cardiac Vagal Tone, defensiveness, and motivational style.

Cardiac Vagal Tone has been proposed as a stable biological marker for the ability to sustain attention and regulate emotion [Porges, Monographs of the Society for Research in Child Development 59 (1994) 167-186]. Vagal tone is a physiological index of parasympathetic nervous system influence on the heart that has predicted a number of emotional behaviors and styles in infants, children, and adults. Little research, however, has sought to explore the link between vagal tone and established variables relating to personality and self-regulation.