Three hypotheses tested relationships between cardiac responses mediated via the vagus and sustained attention in a population of normal school-age children. These hypotheses addressed the theoretical relationships among resting cardiac vagal tone (using the Porges estimate of respiratory sinus arrhythmia, V), performance measures of sustained attention, and cardiac reactivity during sustained attention. Thirty-two fourth and fifth grade children performed a continuous performance task while their electrocardiograms were monitored. Children with higher resting levels of V performed better on the first 3-min block of the continuous performance task. Additionally, levels of V were significantly reduced across the blocks of the 9-min task for all children. No relationships were found between resting levels of V and change in either V or heart period during task performance. These findings support two of the three hypotheses proposed by Porges regarding individual differences in cardiac vagal tone and sustained attention.

In this prospective longitudinal study, vagal tone and heart period were measured at 2 months and at 5 years in children and their mothers to evaluate the development of vagal regulation at rest and during an environmental task. Child baseline vagal tone and heart period were discontinuous; mother baseline vagal tone was discontinuous, but heart period was continuous. Group mean baseline-to-task change in vagal tone and heart period were continuous in both children and mothers. Children reached adult levels of baseline vagal tone by 5 years and did not differ from their mothers in baseline-to-task change in vagal tone or heart period. Baseline vagal tone tended to be stable, but baseline heart period and baseline-to-task change in vagal tone and heart period were unstable in children; both were stable in mothers. Baseline-to-task change in vagal tone showed consistent child-mother concordance. These findings contribute to understanding psychophysiological development, especially the ontogenesis of the vagal system and its regulatory capacity.

Psychophysiological studies of infants have found a relation between behavioral reactivity and indices of autonomic state. The relation between behavioral reactivity, assessed via maternal report, and autonomic state, assessed via cardiac vagal tone in 9-month-old infants was examined. Cardiac vagal tone was quantified by measuring the amplitude of respiratory sinus arrhythmia. High cardiac vagal tone was associated with greater behavioral reactivity, resulting in maternal reports of more difficult temperament. Stability of the two measures, cardiac vagal tone and difficult temperament, from 9 months to 3 years of age was demonstrated. In addition, 9-month cardiac vagal tone, independent of 9-month temperament, was related to 3-year difficultness with higher 9-month cardiac vagal tone being related to less-difficult 3-year behavior.

This study investigates the role of physiological self-regulation (cardiac vagal tone) in information processing (habituation) in 81 infants. Nucleus ambiguus vagal tone (Vna, a measure of respiratory sinus arrhythmia) was used to index cardiac vagal tone. Physiological self-regulation was operationalized as the change in Vna from a baseline period of measurement to habituation. Decreases in Vna consistently related to habituation efficiency, operationalized as accumulated looking time (ALT), in all infants twice at 2 months and twice at 5 months; however, this relation was accounted for by infants who met an habituation criterion on each task. Among habituators, shorter lookers also had greater Vna suppression during habituation. Within-age and between-age suppression of vagal tone predicted ALT, but ALT did not predict suppression of vagal tone. Physiological self-regulation provided by the vagal system appears to play a role in information processing in infancy as indexed by habituation.

No abstract