Patterns of joint parasympathetic, sympathetic, and adrenocortical activity and their associations with temperament in early childhood.

Evidence has accrued to show that autonomic and adrenocortical systems act in coordination to facilitate responses to environmental opportunities and threats. In the current study, we used cluster analysis to examine whether individual differences in patterns of joint baseline activity among the parasympathetic and sympathetic branches of the autonomic nervous system with the hypothalamic-pituitary-adrenal axis are associated with parent-reported temperamental positive and negative affectivity in 36-month old children. The resulting clusters corresponded to the sensitive, buffered, and vigilant patterns as predicted by the adaptive calibration model of stress responsivity (Del Giudice et al., 2011) and included a novel pattern. Cluster memberships predicted differences in overall negative affectivity and its subscales, but no associations were found with positive affectivity. These results provide evidence that the joint activity of physiological systems at rest may underlie temperamental differences in negative affect.