Parental supportive emotional expressivity could contribute to children\'s prosocial behaviors, and such an effect may differ for children with different levels of resting respiratory sinus arrhythmia (RSA). This study disentangled the stable differences across dyads (i.e., between-person effects) from the dynamic associations between parental expressivity and children\'s prosocial behaviors within dyads (i.e., within-person effects) and determined how resting RSA functioned as a susceptibility factor in such effects. The longitudinal design consisted of three measurements with a 1-year interval performed among 208 school-aged children (48.6% girls; Han nationality) and their parents (153 mothers and 55 fathers). The initial measurement was conducted when the children were 7 years old (Mage  = 7.13, SDage  = .33). Resting RSA was calculated at the first measurement; parents reported children\'s prosocial behaviors and parental expressivity at each of the three measurements. The results demonstrated significant between- and within-person effects of parental expressivity on children\'s prosocial behaviors and found a moderating role of children\'s resting RSA in the within-person effects. These findings suggest that children displayed more prosocial behaviors when parents showed more supportive expressivity both across and within dyads, and higher resting RSA operated as a differential susceptibility factor in the intraindividual fluctuations in parental expressivity.

Internet addiction (IA) has become a global concern among college students. To explore the psychophysiological mechanism that is related to IA, this study investigated the role of resilience, loneliness, and resting respiratory sinus arrhythmia (RSA) in IA through a moderated mediation model. A group of 108 (Mage = 18.93, SD = 0.914; 68 male) Chinese undergraduate students completed questionnaires of resilience, loneliness, and IA. Physiological data were collected during their visit to a university laboratory. Results revealed that loneliness mediated the negative association between resilience and IA, with resting RSA and resilience interactively predicted loneliness. Specifically, resilience was negatively related to loneliness only when students had low, rather than high, levels of resting RSA. These findings enrich our understanding of how resilience is related to college students\' IA and highlight the protective role of resting RSA in this association.

Trait impulsiveness is a multifaceted construct that includes motor-, attention/cognitive- and non-planning facets, but how specific impulsiveness facets are associated with the deficit of response inhibition is not well understood. Resting respiratory sinus arrhythmia (RSA), which is considered as an index of cardiac vagal tone has been demonstrated to play a moderating role in the associations between many individual\'s variables. Whether resting RSA moderates the relationships between the facets of trait impulsiveness and response inhibition remains unknown. To examine these issues, data of self-reported trait impulsiveness, as assessed using the Barratt Impulsiveness Scale (BIS-II), 5-min resting RSA, and response accuracy (ACC) on a modified Go/NoGo task were collected from 132 college students. Results indicated that ACC of NoGo condition on the Go/NoGo task was negatively correlated with BIS motor and BIS total. Trait motor impulsiveness negatively predicted ACC of NoGo condition on the Go/NoGo task in the low resting RSA group but not in the high resting RSA group. This finding suggests that cardiac vagal tone could moderate the association between trait impulsiveness, especially motor impulsiveness, and deficits of response inhibition.

The present study sought to investigate the association between social phobia symptoms and self-reported physical symptoms and the moderation effect of resting respiratory sinus arrhythmia (RSA) on this link. Data of 5-min resting RSA, social phobia symptoms assessed by the Social Phobia Scale, and physical symptoms assessed by the Cohen-Hoberman Inventory of Physical Symptoms were collected from 167 undergraduate students. Results indicated that higher levels of social phobia symptoms were associated with higher levels of self-reported physical symptoms. Resting RSA played the moderating role in the link between social phobia symptoms and self-reported physical symptoms, such that social phobia symptoms were positively associated with self-reported physical symptoms among individuals with low resting RSA, whereas this association was nonsignificant among individuals with high resting RSA. These findings suggest that high resting RSA as a physiological marker of better self-regulation capacity might buffer the effect of social phobia symptoms on physical health.

Respiratory sinus arrhythmia (RSA) has been examined as a psychophysiological marker of stress vulnerability. Research indicates that low resting RSA is associated with physical and mental health problems, including posttraumatic stress disorder (PTSD). Some research suggests that people diagnosed with PTSD have lower RSA than people without PTSD, but findings have been mixed and the overall magnitude of this effect is unknown, indicating the need for a comprehensive meta-analysis. This meta-analysis examined the association between PTSD and baseline RSA in 55 studies, including 12 unpublished studies, with a total sample size of 6689. Studies were included if they used a PTSD measure, a baseline measure of RSA, and involved humans. Studies were excluded if they were not available in English, did not present quantitative data, presented duplicate data, were a case series, or did not provide results required for computing an effect size. The meta-analysis indicated there is a small but significant association between PTSD and RSA (g = -0.26; 95% CI = -0.35, -0.16) with moderate heterogeneity. Moderator analyses suggested that effects are larger for adults than for children and for DSM-5 PTSD measures than for non-DSM referenced measures. We found some evidence for publication bias among the meta-analysis findings. Overall, there is a small but reliable association between PTSD and lower resting RSA, providing support for further research examining the complex relationship between parasympathetic activity and PTSD.