Sw. Porges et al., CARDIAC VAGAL TONE - STABILITY AND RELATION TO DIFFICULTNESS IN INFANTS AND 3-YEAR-OLDS, Developmental psychobiology, 27(5), 1994, pp. 289-300
Psychophysiological studies of infants have found a relation between b
ehavioral reactivity and indices of autonomic state. The relation betw
een behavioral reactivity, assessed via maternal report, and autonomic
state, assessed via cardiac vagal tone in 9-month-old infants was exa
mined. 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 m
ore difficult temperament. Stability of the two measures, cardiac vaga
l 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 behav
ior. (C) 1994 John Wiley and Sons, Inc.