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Quantifying the dynamic nature of vagal responsivity in infancy: Methodological innovations and theoretical implications
Author(s) -
Somers Jennifer A.,
Curci Sarah G.,
Luecken Linda J.
Publication year - 2021
Publication title -
developmental psychobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 93
eISSN - 1098-2302
pISSN - 0012-1630
DOI - 10.1002/dev.22018
Subject(s) - vagal tone , developmental psychology , psychology , social competence , audiology , heart rate variability , heart rate , medicine , social change , blood pressure , economics , economic growth
According to polyvagal theory, rapid modulation of the vagal brake develops early in infancy and supports social interactions. Despite being viewed as a dynamic system, researchers typically assess vagal regulation using global measures of respiratory sinus arrhythmia (RSA; an index of vagal tone). This study sought to capture the dynamic property of RSA and evaluate individual differences in within‐infant RSA responsivity during mother–infant interaction. RSA was evaluated in a sample of 135 6‐month‐old Mexican‐American infants during a 5‐min free play task. Mothers reported on their children's behavioral problems and competence at 18 months using the Brief Infant‐Toddler Social and Emotional Assessment. Time‐varying estimates of infant RSA during the interaction were obtained using a multiple window technique and spectrogram analysis. Using structural equation modeling, we evaluated whether within‐infant SD of RSA predicted infants’ behavioral problems and competence at 18 months, after adjusting for infants’ mean RSA and covariates. Greater within‐infant SD of RSA predicted more behavior problems at 18 months. This study demonstrates that assessing intra‐individual variability in RSA, or the extent to which infants fluctuate around their average level of RSA during a task, enhances our ability to test polyvagal theory's central tenet: vagal regulation supports well‐regulated social interaction.