Investigating the Convergence of Cardiac and Behavioural Indicators of Distress Regulation in Toddlerhood
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The ability to respond and regulate from distress is critical to everyday functioning for children and adults. Profiles of distress responding have been linked with individual differences in psychological and cognitive outcomes across development. However, no studies to date have examined the longitudinal patterns of both physiological and behavioural distress responding within a high distress context (i.e., pain) in toddlerhood. This dissertation consists of three studies examining the development of behavioural and physiological distress regulation in the second and third years of life as well as the convergence between these distress indicators over time. Study 1 is a published systematic review (Waxman, DiLorenzo, & Pillai Riddell, 2020) that synthesizes the direction and magnitude of the relation between behavioural and cardiac indicators of distress in toddlerhood (12 to 47 months of age). Study 1 revealed that the magnitude of the association between behavioural and most cardiac indicators of distress might be smaller than previously expected (i.e., Cohens d < 0.2). However, methodological differences may also be responsible for study heterogeneity. Study 2 (Waxman et al., 2020) and Study 3 (Waxman et al., in press) were based on an ongoing longitudinal cohort of caregiver-infant dyads observed during vaccination appointments during the second year of life (12-month vaccination [N=158], 18-month vaccination [N=122]). Study 2 used path analyses to investigate the predictive and concurrent relations between toddlers pain-related behavioural distress and cardiac (i.e., heart rate [HR], respiratory sinus arrhythmia) responses during 12- and 18-month vaccinations. Study 2 demonstrated that behavioural and cardiac indicators of pain-related distress during 12- and 18-month vaccinations reflect unique aspects of the nociceptive response. Study 3 utilized parallel-process growth mixture modeling to describe patterns of distress responses to vaccinations as indexed by both pain-related behavioural distress and HR at 12 and 18 months. Study 3 revealed developmental differences and increasing variability in behavioural and cardiac distress responses across the second year of life. Clinical implications and suggestions for future research are discussed.