Effortful Control Predicts Individual Differences in Cardiac Vagal Regulation _

1. Effortful Control Predicts Individual Differences in Cardiac Vagal Regulation_ Derek P. Spangler, Ned Cauley, & Bruce H. Friedman Mind-Body Laboratory INTRODUCTION ANALYSES • Effortful control (EC) reflects individual differences in the ability to control attention and emotion across the lifespan (Rothbart & Bates, 1998). Identifying the physiological profile of high EC may help indicate autonomic mechansisms that can be modified to ameliorate deficient emotion regulation. • Cardiac vagal tone is often used as biomarker for self-regulation at multiple levels. (Thayer & Lane, 2000) and is typically indexed by high-frequency heart rate variability (HF HRV) (Cacioppo et al., 1994). • EC has been shown to positively relate to resting HF HRV among children and adolescents (Chapman et al., 2010); however, there have been few attempts to test EC’s relation to more dynamic measures of cardiac vagal regulation in adult samples (Brooker & Buss, 2010). • The purpose of this study is to test whether high levels of EC in adulthood are associated with enhanced vagal regulation of heart period (HP) changes during mental stress. • Physiological variables’ task values were subtracted from baseline values to yield IBI and HRV reactivity scores. The correlation between IBI and HRV changes was used to reflect cardiac vagal regulation. • A multiple regression equation was used to test whether EC moderates the relation between HF HRV and IBI reactivity scores. Predicted IBIch= β0+ β1 HF HRVch + β2EC+ β3HF HRVch*EC IBI change RESULTS • EC was shown to significantly moderate the relation between HF HRV change and mean IBI change from baseline, ß = -.412, t(31) = -2.424, p = .021. • Simple slope analyses indicated that IBI and HF HRV reactivity were positively related for those scoring low in EC, ß = .909, t(31) = 2.588, p = .015, but negatively related for those scoring high on EC, ß = -.821, t(31) = -1.90, p = .067. • HP shortening during speech preparation tended to occur with increases and decreases in vagal outflow for those high and low in EC, respectively METHOD Subjects 35 undergraduate psychology students -Age: M = 20.17 (SD= 2.107) -Non-smokers with no cardiovascular abnormalities Self-report questionnaires: -Effortful Control scales of the Adult Temperament Questionnaire-Short Form (7-point Likert) Physiological measures: -Interbeat intervals (IBI) were derived from electrocardiography (ECG) signals to indicate HP. -HF HRV (.12-.25 Hz) was calculated with the Fast-Fourier Transform algorithm to index vagal tone. Task: A 3-minute preparation of a speech regarding one’s personal strengths and weaknesses Procedure: Phsyiological measures assessed during three 3-min periods: Vanilla baseline Speech preparation  Recovery HF HRV change DISCUSSION • Contrary to the hypothesis, these results suggest that high EC is marked by lower vagal regulation of HP during mental stress, while low EC relates to higher cardiac vagal control. • These findings may relate to the tendency of HF HRV to increase during emotion regulation (Butler, Wilhelm, & Gross, 2006), as persons high in EC are suggested to more often down-regulate negative emotion (Kochanska, 2000; Rothbart & Bates, 1998). Limitations: • Inclusion of sympathetic measures could provide a better picture of EC’s autonomic characteristics. • The speech preparation task may have not been sufficiently distressing.