Moderate baseline vagal tone predicts greater prosociality in children

Family cohesion moderates the inverted U-shaped curve between resting RSA and children's empathy

Resting respiratory sinus arrhythmia (RSA) and family cohesion may jointly influence children's empathy. Resting RSA has been found to exhibit an inverted U-shaped relation with empathy, and family cohesion is a psychosocial correlate of children's empathy that may moderate this relation. The present study recruited 182 first-grade children as participants (87 girls, Mage = 7.02, SDage = 0.36). Parents completed questionnaires to assess family cohesion and children's empathy. The SOMNOtouch RESP device was utilized to collect resting electrocardiogram data and calculate resting RSA. The results showed that family cohesion significantly moderated the inverted U-shaped curve between resting RSA and children's empathy. High family cohesion served as a protective factor in mitigating the negative impact of high resting RSA on empathy but could not buffer the negative effect of extremely low resting RSA on empathy among children. The findings suggest a role for high family cohesion in promoting empathy in children with moderate to high resting RSA.

Paternal depressive symptoms and infant respiratory sinus arrhythmia predict empathy-related behaviors

Children with specific psychophysiological profiles may be more strongly affected by adverse environmental experiences. Guided by a biopsychosocial perspective, we examined whether infant respiratory sinus arrhythmia (RSA), an index of parasympathetic functioning, moderates the associations between paternal postpartum depression (PPD) symptoms and infants' observed empathy-related responses. Participants were 142 families with infants (51% female) assessed at two time points. At T1 (3 months of age), fathers reported their depressive symptoms. Infants' cardiac activity was recorded during rest and estimates of RSA were calculated. In addition, infants' empathy-related responses during a maternal distress simulation were observed and rated at T2 (12 months of age). Higher paternal PPD at T1 predicted higher infant affective (i.e., affective concern) and cognitive (i.e., inquiring behaviors) responses to maternal distress at T2. Infant RSA moderated this relationship for cognitive responses, with a significant positive association only for children with high or average RSA. These findings contribute to the understanding of the psychophysiological mechanisms that support empathy development.

Racial biases, facial trustworthiness, and resting heart rate variability: unravelling complexities in pain recognition

The study explores whether racial identity and appearance-based trustworthiness judgments can affect recognition of pain in medical students differing in levels of resting heart rate variability (HRV), a measure of parasympathetic control of the heart. After undergoing HRV assessment, 68 medical students (37 females) participated in a dynamic pain recognition task, viewing video clips of White and Black faces, which differed in perceived trustworthiness based on facial appearance, transitioning from neutral to intense pain expressions. Response time, pain intensity attribution and treatment recommendations were analyzed. Pain was recognized slower and estimated as less intense in Black compared to White faces, leading to a lower likelihood of recommending therapy. Pain recognition was faster for untrustworthy-looking White faces compared to trustworthy ones, while perceived trustworthiness had a minimal impact on the speed of pain recognition in Black faces. However, untrustworthy-looking faces were estimated to express more pain, particularly for Black faces. Notably, these biases were more pronounced in individuals with low, rather than high, resting HRV. Considering that therapeutic decisions mirrored pain intensity attribution, it would be important to increase awareness of these biases during medical training in order to promote equity in future pain assessment and treatment.

Autonomic nervous system activity correlates with peak experiences induced by DMT and predicts increases in well-being

BACKGROUND

Non-ordinary states of consciousness induced by psychedelics can be accompanied by so-called "peak experiences," characterized at the emotional level by their intensity and positive valence. These experiences are strong predictors of positive outcomes following psychedelic-assisted therapy, and it is therefore important to better understand their biology. Despite growing evidence that the autonomic nervous system (ANS) plays an important role in mediating emotional experiences, its involvement in the psychedelic experience is poorly understood. The aim of this study was to investigate to what extent changes in the relative influence of the sympathetic (SNS) and parasympathetic nervous systems (PNS) over cardiac activity may reflect the subjective experience induced by the short-acting psychedelic N,N-Dimethyltryptamine (DMT).

METHODS

We derived measures of SNS and PNS activity from the electrocardiograms of 17 participants (11 males, mean age = 33.8 years, SD = 8.3) while they received either DMT or placebo.

RESULTS

Results show that the joint influence of SNS and PNS ("sympathovagal coactivation") over cardiac activity was positively related to participants' ratings of "Spiritual Experience" and "Insightfulness" during the DMT experience, while also being related to improved well-being scores 2 weeks after the session. In addition, we found that the state of balance between the two ANS branches ("sympathovagal balance") before DMT injection predicted scores of "Insightfulness" during the DMT experience, as well as subsequent sympathovagal coactivation.

CONCLUSION

These findings demonstrate the involvement of the ANS in psychedelic-induced peak experiences and may pave the way to the development of biofeedback-based tools to enhance psychedelic therapy.

Moderate cardiac vagal tone predicts more cooperation in highly sensitive individuals

Cooperation, as a mutual collaboration, is a defining feature of human social life. Individual characteristics can influence cooperation. Recent studies have shown a quadratic relationship between cardiac vagal tone (CVT), an index of self-regulation, and prosocial behaviors. Individual differences in cooperation might also vary as a function of people's environmental sensitivity (ES), i.e., may be influenced by individual differences in the perception and processing of inner and external stimuli. We tested the direct and interactive effect of CVT and ES on cooperative behaviors in two independent samples. We measured heart rate and engagement in cooperative acts in 80 young adults (M = 23.61; SD = 1.60) who were also asked to self-report on ES. We found an inverted-U relationship between CVT and cooperative behaviors. ES, on the other hand, did not predict differences in cooperative behaviors but moderated the relationships between CVT and cooperation, although the magnitude of this result was small. Specifically, only among individuals with higher ES cooperative behaviors change as a function of CVT. Highly sensitive individuals with lower or higher CVT, were less cooperative than low sensitive ones. Subsequently, we replicated the same study design in a second sample of 88 undergraduate students (M = 23.69; SD = 4.91). Once again, we found evidence supporting the presence of an inverted-U relationship between CVT and cooperative behaviors, and we also found that ES moderated the relationships between the quadratic CVT term and cooperation.

Parasympathetic regulation and support from family and friends predict prosocial development in U.S. Mexican-origin adolescents

Both parasympathetic nervous system regulation and receipt of social support from close relationships contribute to prosocial development, although few studies have examined their combined influences in adolescence and particularly within racially and ethnically minoritized populations. In this longitudinal study of 229 U.S. Mexican-origin adolescents (48% female-identifying), youths reported on receipt of social support from family and friends from 10 to 16 years, had their baseline respiratory sinus arrhythmia (RSA) measured at 17 years, reported their prosocial behavior and completed the Mind in the Eyes test to assess cognitive empathy at 17 and 19 years, and reported their prosocial civic behavior (i.e., community activity) at 19 years. Family social support predicted prosocial behavior at 17 years, and friend social support predicted prosocial civic behavior at 19 years. Compared to youths with lower or higher baseline RSA, youths with moderate RSA reported more prosocial civic behavior, had greater cognitive empathy, and tended to report more general prosocial behavior at 19 years. The quadratic association between baseline RSA and cognitive empathy was stronger for youths with greater family social support. These findings are the first to extend the evidence that moderate baseline parasympathetic nervous system activity supports prosocial development into late adolescence and with the U.S. Mexican-origin community, and these findings address calls for more integrative biopsychosocial studies of prosociality. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Moderate cardiac vagal tone is associated with more cooperation in children

Childhood is a crucial period for prosocial development, including cooperative behaviors. Recent studies have shown a quadratic relation (inverted U-shape curve) between cardiac vagal tone (CVT) and various prosocial emotions and behaviors in children, but data are lacking on cooperative behaviors. In a sample of 111 school-aged children (M = 7.77; SD = 1.24, range: 6-11), we tested the association between the root mean square of successive differences in interbeat intervals (RMSSD) at rest, and cooperative behavior in a task designed to be comparable to a stag hunt game. We found evidence for an association between RMSSD and cooperation that follows an inverted U-shape. In addition, older children were more likely to cooperate than younger children. Lastly, we found an interaction between RMSSD and age such that the association between RMSSD and cooperation behavior was present for younger but not older children. In addition, we proposed an extension of the Johnson-Neyman test to assess the significant region of interaction between age and the linear and quadratic RMSSD. These results add to a growing literature suggesting that moderate RMSSD is associated with greater prosocial behavior and provide novel evidence that this association extends to children's cooperation.

Vagal Flexibility Moderates the Links between Observed Sensitive Caregiving in Infancy and Externalizing Behavior Problems in Middle Childhood

This study explored how patterns of physiological stress reactivity underpin individual differences in sensitivity to early rearing experiences and childhood risk for psychopathology. To examine individual differences in parasympathetic functioning, past research has largely relied on static measures of stress reactivity (i.e., residual and change scores) in infancy which may not adequately capture the dynamic nature of regulation across contexts. Using data from a prospective longitudinal study of 206 children (56% African Americans) and their families, this study addressed these gaps by employing the latent basis growth curve model to characterize the dynamic, non-linear patterns of change in infants' respiratory sinus arrhythmia (i.e., vagal flexibility) across the Face-to-Face Still-Face Paradigm. Furthermore, it investigated whether and how infants' vagal flexibility moderates the links between sensitive parenting, observed during a free play task when children were 6 months of age, and parent-report of children's externalizing problems at 7 years of age. Results of the structural equation models revealed that infants' vagal flexibility moderates the predictive relations between sensitive parenting in infancy and children's later externalizing problems. Simple slope analyses revealed that low vagal flexibility, characterized by less suppression and flatter recovery patterns, exacerbated risk for externalizing psychopathology in the context of insensitive parenting. Children with low vagal flexibility also benefited most from sensitive parenting, as indicated by the lower number of externalizing problems. Findings are interpreted in the light of the biological sensitivity to context model and provide evidence for vagal flexibility as a biomarker of individual's sensitivity to early rearing contexts.

Examining the Relations Between Children's Vagal Flexibility Across Social Stressor Tasks and Parent- and Clinician-Rated Anxiety Using Baseline Data from an Early Intervention for Inhibited Preschoolers

Early behavioral inhibition (BI) is a known risk factor for later anxiety disorder. Variability in children's parasympathetic nervous system (PNS) functioning may provide insight into the substantial heterogeneity in anxiety outcomes for children high in BI. However, gaps persist due to an over-reliance on static measures of functioning, which limits our ability to leverage PNS functioning to identify risk for anxiety. We address these gaps using baseline data from an early intervention study of inhibited preschoolers by characterizing vagal flexibility (VF), an index of non-linear change in PNS functioning, across social stressor tasks and by examining the associations between VF and anxiety. One hundred and fifty-one parents and their 3.5- to 5-year-old children were selected on the basis of BI to participate in an early intervention program (ClinicalTrials.gov registration: NCT02308826). A structural equation modeling framework was used to model children's VF across tasks designed to mimic exposure to novel social interactions and to test the predictive links between VF and anxiety. Children who showed less VF, characterized by less suppression and flatter recovery, were rated by both parents and clinicians as more anxious. Moreover, a multiple group model showed that children meeting diagnostic criteria for social anxiety disorder demonstrated significantly less VF across social stressor tasks. Among inhibited youth, reduced VF is a risk factor for anxiety and may reflect an individual's reduced capacity to actively cope with external demands. Study results contribute to our understanding of the regulatory processes underlying risk for anxiety in early childhood.

A dynamic systems perspective towards executive function development: Susceptibility at both ends for inhibitory control

In light of the dynamic systems perspective, the current study expanded existing literature by examining the moderating effect of maternal sensitivity on the quadratic association between infant negative reactivity and future executive function development. Using a longitudinal, multimethod design, we addressed executive function development among preschoolers. This study utilized data from the Family Life Project (N = 1292). Infant negative reactivity at 6 months, maternal sensitivity across first 3 years, and executive functions during preschool age were observational assessed. A path model with moderation analyses revealed a U-shaped quadratic association between infant negative reactivity and preschoolers' inhibitory control, only when maternal sensitivity was high. The results suggest that maternal sensitivity may assist infants with both low and high, but not moderate, levels of negative reactivity towards better executive function development. Findings support the ongoing nonlinear person-environment interplay during early years of life.

Encouraging a Peer in Need: The Impacts of Social Anxiety and Peer Familiarity

Extant research has produced conflicting findings regarding the link between social fearfulness and prosocial behavior, with some studies reporting negative relations and others reporting null effects. Furthermore, these studies have focused predominantly on toddlerhood, and few have examined prosociality between peers. The present study investigated whether the link between social anxiety and a prosocial behavior (i.e., providing encouragement) varied depending on interpersonal and situational factors (i.e., one's familiarity with a peer, the level of support sought by a peer, respectively). We tested this question using a multimethod approach, which included an ecologically valid stress inducing task and dyadic design with a sample of 9- to 10-year-olds (N = 447). Results revealed that social anxiety was related negatively to providing encouragement among familiar and unfamiliar dyads. In familiar dyads, however, this main effect was qualified by an interaction with the level of support sought by one's peer. Compared to those low in social anxiety, children high in social anxiety provided relatively less encouragement in response to higher levels of support seeking from their peers. The findings are considered in relation to theorizing regarding the effect of overarousal on children's prosocial behavior.

Autonomic Arousal, Ethical Guilt, and Externalizing Behavior in Childhood: A Clinical Extension and Replication

Lower autonomic arousal is associated with higher externalizing behavior in childhood but the mechanisms explaining this link are still debated. One possibility is that lower autonomic arousal makes it difficult for children to anticipate or express social emotions, such as ethical guilt rooted in concern for others, thereby increasing their likelihood of externalizing behavior. However, evidence for this social-emotional hypothesis has been limited to community samples. The present study included ethnically diverse samples of 150 typically developing children (M_age = 8.01 years; 50% girls) and 62 children referred for clinically elevated externalizing behavior (M_age = 9.16 years; 16% girls; N = 212). Caregivers reported children's externalizing behavior. Children's respiratory sinus arrhythmia (RSA) was measured as an indicator of parasympathetic activity in response to hypothetical vignettes depicting externalizing behavior. Children's ethical guilt was coded from semi-structured interviews following each vignette. Greater RSA increases (indicating a low-arousal, rest-and-digest response) were associated with lower ethical guilt. Lower ethical guilt was associated with higher externalizing behavior. A significant indirect effect showed that RSA increases were associated with higher externalizing behavior through relative lapses in ethical guilt. Results were consistent across and within the community and clinical samples. Theoretical and practical implications for clinically elevated externalizing behavior are discussed.

The moderating role of attachment in the association between physiological synchrony in married couples and supportive behavior in the transition to parenthood

Despite supportive behaviors playing a central role in intimate relationships, the extent to which physiological and psychological factors are involved in the quality of the observed spousal support, remains largely unknown. From a physiological stance, cardiac synchrony has been identified as an important component involved in dyadic interpersonal interactions. This study aims to examine whether individual differences in attachment determine, at least to some extent, whether cardiac synchrony enhances or impedes the quality of the observed spousal support. Specifically, this study examines whether attachment style moderates the biobehavioral link between positive cardiac synchrony and observed spousal support. A total of 58 couples expecting their first child participated in a supportive interaction while their cardiovascular responses were recorded, and the quality of their caregiving behaviors was coded. Results indicated that couples' cardiovascular dynamics were synchronized during the supportive interaction. Furthermore, attachment moderated the association between positive cardiac synchrony and the behavioral manifestation of support, such that cardiac synchrony was negatively associated with the quality of support when offered by caregivers with higher scores of attachment anxiety. Our findings show that for those caregivers who have higher levels of anxious attachment-being synchronized with their care seeking spouses is associated with difficulties in providing effective support. We discuss these findings in the context of the emotion regulation difficulties characteristic of anxious attachment patterns. These findings suggest that future work could benefit from performing comprehensive studies that consider physiological, behavioral, and psychological constructs simultaneously.

Heart rate variability moderates the effects of COVID-19-related stress and family adversity on emotional problems in adolescents: Testing models of differential susceptibility and diathesis stress

The COVID-19 pandemic is a unique period of stress, uncertainty, and adversity that will have significant implications for adolescent mental health. Nevertheless, stress and adversity related to COVID-19 may be more consequential for some adolescents' mental health than for others. We examined whether heart rate variability (HRV) indicated differential susceptibility to mental health difficulties associated with COVID-19 stress and COVID-19 family adversity. Approximately 4 years prior to the pandemic, we assessed resting HRV and HRV reactivity to a well-validated stress paradigm in 87 adolescents. During the pandemic, these adolescents (ages 13-19) reported on their health-related stress and concerns about COVID-19, family adversity related to COVID-19, and their recent emotional problems. The association between COVID-19 stress and emotional problems was significantly stronger for adolescents who previously exhibited higher resting HRV or higher HRV reactivity. For adolescents who exhibited lower resting HRV or HRV augmentation, COVID-19 stress was not associated with emotional problems. Conversely, lower resting HRV indicated vulnerability to the effect of COVID-19 family adversity on emotional problems. Different patterns of parasympathetic functioning may reflect differential susceptibility to the effects of COVID-19 stress versus vulnerability to the effects of COVID-19 family adversity on mental health during the pandemic.

Autonomic profiles and self-regulation outcomes in early childhood

This study examined autonomic profiles in preschoolers (N = 278, age = 4.7 years) and their relations to self-regulation outcomes concurrently and one year later, in kindergarten. Children's sympathetic (preejection period [PEP]) and parasympathetic activity (respiratory sinus arrythmia [RSA]) were measured at rest and during cognitive and emotional tasks. Three self-regulatory competencies were assessed: executive functions, emotion regulation and behavioral regulation. Executive functioning was measured at ages 4 and 5 using laboratory tasks designed to assess updating/working memory, inhibitory control, and cognitive flexibility. Emotion regulation was observed during emotionally distressing tasks in the laboratory, both at ages 4 and 5. Behavioral regulation and emotional reactivity were assessed via teacher ratings in kindergarten, at age 5. Latent profile analysis yielded four autonomic profiles: moderate parasympathetic inhibition (45%), reciprocal sympathetic activation (26%), coinhibition (25%), and high sympathetic activation (7%). The reciprocal sympathetic activation group showed better executive functioning in preschool and kindergarten, particularly compared to the high sympathetic activation group. The moderate parasympathetic inhibition group showed lower emotional reactivity and better behavioral regulation in kindergarten, compared to the other three groups. Findings suggest that autonomic profiles meaningfully associate with self-regulation outcomes in early childhood, such that certain profiles relate to better self-regulation than others.

Parental warmth predicts more child pro-social behaviour in children with better emotion regulation

Parental warmth and child emotion regulation have each been implicated in the development of child pro-social behaviours; however, their interactive benefits remain unclear. In this multi-method, multi-cohort longitudinal study, we examined the effect of parental warmth on child pro-social behaviours at different levels of child emotion regulation. We collected data from 6- and 10-year-olds in Canada (N_T1  = 233; M_age  = 8.41; SD = 2.08) and their parents. Parental warmth, child emotion regulation, and child pro-social behaviours were assessed via parent report. Children's baseline respiratory sinus arrhythmia (RSA; an indicator of cardiac regulatory capacity) was assessed as a correlate of emotion regulation. Child pro-social behaviours were assessed concurrently and 1 year later. Results showed that higher parental warmth was related to higher concurrent prosocial behaviours and greater increases in prosocial behaviours over 1 year. These effects were strengthened for children with higher emotion regulation whether measured by parent report or RSA. We discuss implications for understanding pro-social development in middle childhood from a strengths-based perspective.

Associations between burnout symptoms and social behaviour: exploring the role of acute stress and vagal function

BACKGROUND

The study aimed to investigate the link between burnout symptoms and prosocial behaviour, as well as the role of acute stress and vagally-mediated heart rate variability (vmHRV) on this association.

METHODS

Seventy men were randomly assigned to either the stress or the control condition of the Trier Social Stress Test for Groups (TSST-G). Prosocial behaviour was assessed via a social decision-making paradigm during the respective TSST-G condition.

RESULTS

Correlation analyses revealed negative correlations between prosocial behaviour and burnout symptoms. Acute stress was also associated with reduced prosocial behaviour, whereas no interaction effects with burnout symptoms could be revealed. Exploratory analyses showed that vmHRV was negatively correlated with burnout symptoms during the social decision-making paradigm but did not mediate the link between burnout and prosocial behaviour.

CONCLUSION

In conclusion, we report first experimental evidence that burnout symptoms are negatively associated with prosocial behaviour. Further studies are needed to explore the causal relations.

Autism Spectrum Disorder in Children Is Not Associated With Abnormal Autonomic Nervous System Function: Hypothesis and Theory

The quest to understand the pathophysiology of autism spectrum disorder (ASD) has led to extensive literature that purports to provide evidence for autonomic dysfunction based on heart rate and heart rate variability (HRV), in particular respiratory sinus arrhythmia (RSA), a measure of parasympathetic functioning. Many studies conclude that autism is associated with vagal withdrawal and sympathetic hyperactivation based on HRV and electrodermal analyses. We will argue that a critical analysis of the data leads to the hypothesis that autonomic nervous system dysfunction is not a dominant feature of autism. Most children with ASD have normal parasympathetic baseline values and normal autonomic responses to social stimuli. The existing HRV and electrodermal data cannot lead to the conclusion of an over-excitation of the sympathetic nervous system. A small subgroup of ASD children in experimental settings has relatively low RSA values and relatively high heart rates. The data suggest that this is likely associated with a relatively high level of anxiety during study conditions, associated with co-morbidities such as constipation, or due to the use of psychoactive medication. Many studies interpret their data to conform with a preferred hypothesis of autonomic dysfunction as a trait of autism, related to the polyvagal theory, but the HRV evidence is to the contrary. HRV analysis may identify children with ASD having autonomic dysfunction due to co-morbidities.

Inhibitory control, dyadic social behavior, and mental health difficulties in preschoolers

Although inhibitory control is typically associated with positive outcomes, several theoretical frameworks suggest that too little and too much inhibitory control may be problematic. Using a longitudinal, latent variable approach, we examined whether a multi-method index of inhibitory control at Time 1 (N = 105, 52 girls, M_age  = 3.50 years, 87% White) predicted observed social behavior with an unfamiliar peer and maternal report of preschoolers' mental health difficulties at Time 2 (M_age  = 4.76 years). Data collection occurred between 2017 and 2019. Inhibitory control displayed a U-shaped relation with prospective outcomes, where high and low levels of inhibitory control were associated with higher levels of avoidant social behaviors and mental health difficulties. The results are discussed in the context of under- and over-regulation in understanding individual differences in children's social behavior and mental health difficulties.

Parental history of childhood maltreatment and child average RSA shape parent-child RSA synchrony

We examined whether dynamic parent-child RSA synchrony varied by individual differences in child average RSA and parental history of childhood maltreatment (CM), which has been linked to parental behavioral and physiological dysregulation. We also examined whether RSA synchrony was curvilinear, reflecting homeostatic regulation. Synchrony was defined as the dynamic association between parent and child RSA reactivity (change relative to their own mean) within epoch across a challenging task. Eighty-three mother-preschooler and 61 father-preschooler dyads participated. State-trait modeling showed that RSA synchrony was curvilinear such that significant relations were only found at lower and higher child reactivity. Children's higher task average RSA predicted maternal RSA augmentation and lower task average RSA predicted maternal RSA withdrawal, regardless of whether child reactivity in the moment was low or high, suggesting individual differences in child regulatory capacity were associated with dynamic maternal reactivity. When maternal CM history and child average RSA were both higher, mothers showed RSA augmentation. Father-child synchrony was not moderated by child average RSA but greater paternal CM history predicted fathers' greater RSA withdrawal regardless of whether child RSA reactivity was low or high. Findings offer novel insights into the nature and meaning of RSA synchrony with parents at risk.

Curvilinear Relations Between Preschool-Aged Children's Effortful Control and Socioemotional Problems: Racial-Ethnic Differences in Functional Form

The majority of studies of preschool-aged children's self-regulation presume that their higher levels of self-regulation are concurrently and prospectively associated with fewer externalizing and internalizing problems. This assumes their relations are only linear in form and negative, but studies with community samples of mostly non-Hispanic White children have found curvilinear or positive relations between self-regulation and socioemotional problems in early childhood. This cross-sectional study tests linear and quadratic relations between children's behavioral battery assessed effortful control and parent rated externalizing and internalizing problems, and whether their functional forms differ across racial-ethnic groups in a diverse sample of 2.5- to 3.5-years-olds (N = 72) from highly educated two-parent households. Child effortful control was negatively related to externalizing, quadratically related to internalizing (albeit marginally), and an interaction between effortful control and race-ethnicity indicated opposite linear relations between effortful control and internalizing problems for different racial-ethnic groups. By integrating tests of curvilinearity and interactions, this study builds on theoretical and empirical work indicating complex relations between the development of self-regulation and psychopathology.

The Heart in the Mind: A Systematic Review and Meta-Analysis of the Association Between Theory of Mind and Cardiac Vagal Tone

Theory of mind (ToM) is the human ability to infer the mental states of others in order to understand their behaviors and plan own actions. In the past decades, accumulating evidence has shown that heart rate variability (HRV), an index of parasympathetic control of the heart, is linked to behavioral regulation, social competence, and social cognition abilities, all implicated-to some extent-in ToM. This study aims to systematically review and meta-analyze the available studies, investigating the relation between ToM and HRV in typically developing people. Six studies were eligible for the meta-analysis, yielding a significant association between HRV and ToM of a small-to-medium effect size (g = 0.44). This result was not influenced by publication bias. Due to the small number of studies eligible for the meta-analysis, it was not possible to test for the effect of categorical moderators. The moderating role of sex and quality of the studies was examined by meta-regression analysis. Moderation analysis did not yield any significant effect; however, at a descriptive level, studies yielding the largest effect size were characterized by the use of high frequency-HRV assessment at rest and the Reading the Mind in the Eyes Test to evaluate ToM abilities. The results preliminarily suggest that tonic HRV might be used as an indicator of the ability to understand the content of mind of others.

Brief induction of loneliness decreases vagal regulation during social information processing

Perceived social isolation, or loneliness, has been repeatedly linked to numerous adverse health outcomes. Much effort has been directed towards elucidating the mechanisms underlying its effects on the cardiovascular system, which may explain the deleterious effects on morbidity and mortality. It has been previously suggested that perceived social isolation can impair effective parasympathetic regulation and physiological adjustment to the demands of the social environment. Thus, the present study aimed at investigating the causal impact of an induction of loneliness on vagal activity during social stimuli processing. In the study, participants (N = 119) were led to anticipate either a future filled with satisfying relationships (Future Belong) or a lonely life (Future Alone). Then, they were asked to complete an implicit emotion regulation task while their cardiovascular activity was recorded. In the Future Belong group, a pattern of vagal suppression was observed between the resting period and task completion, which was followed by vagal recovery during the post-task resting period. However, in the Future Alone group, a change from the baseline HRV was observed only at the beginning of the task, but not during its consecutive stages. Moreover, in participants who believed in the given FA feedback, the initial vagal suppression was absent. These findings provide evidence that even a brief induction of loneliness can result in a blunted vagal suppression during social information processing. It can be hypothesized that the lack of the ability to regulate vagal activity while processing social cues may potentially underlie problems with social engagement and self-control.

Children's altruism following acute stress: The role of autonomic nervous system activity and social support

Altruistic behavior after stress exposure may have important health and psychological benefits, in addition to broader societal consequences. However, so far experimental research on altruism following acute stress has been limited to adult populations. The current study utilized an experimental design to investigate how altruistic donation behavior among children may be influenced by (a) exposure to an acute social stressor, the Trier Social Stress Test modified for use with children (TSST-M), (b) individual differences in stress physiology, and (c) social support from a parent. The sample consisted of 180 children (54.9% male, 45.1% female; mean age = 9.92 years, SD = 0.56 years) randomly assigned to one of three conditions involving the TSST-M: (a) prepare for the TSST-M alone, (b) prepare for the TSST-M with a parent, and (c) no-stress control group. Results revealed that children made larger donations post-stressor if they were alone before the acute stressor, if they had moderate cardiac autonomic balance, reflecting both parasympathetic and sympathetic influence, and if they were older. Children who prepared for the TSST-M with social support from a parent made comparable donations as children in the no-stress control group, in accord with stress buffering models. Increased altruism following acute stress among children suggests that a comprehensive understanding of the human stress response needs to incorporate "tend-and-befriend" behavior-the tendency for humans to show increased altruistic behavior during times of distress.

Adult attachment dimensions: Differential effects on physiological and subjective response during the recollection of childhood memories

The aim of this study was to explore the relationship between adult attachment dimensions and emotional response induced by the recall of potentially painful memories from childhood. A convenience sample of 100 women responded to an interview that focused on experiences with their caregivers during childhood, and a control interview, in counterbalanced order. Skin conductance level (SCL), heart rate (HR), heart rate variability (HRV), as well as subjective distress measures were collected. Results from generalized linear mixed model indicated that individuals high in avoidance showed a pattern of SCL increase from baseline that persisted during rest phases regardless of the topic addressed. Attachment dimensions did not affect HR, neither alone nor interacting with the interviews content, whereas baseline resting vagal tone was the most important factor. No attachment dimensions effects were observed on subjective measures of emotion; the time-varying vagal tone during rest phases did not moderate their relationships. Limited evidence was observed in support of the hypothesis that attachment Avoidance and Anxiety are associated with distinct physiological regulation profiles during the recall of potentially painful childhood memories.

The Development of Generosity From 4 to 6 Years: Examining Stability and the Biopsychosocial Contributions of Children's Vagal Flexibility and Mothers' Compassion

Individual differences in children’s prosocial behaviors, including their willingness to give up something of value for the benefit of others, are rooted in physiological and environmental processes. In a sample of 4-year-old children, we previously found evidence that flexible changes in respiratory sinus arrhythmia (RSA) were linked to donation behavior, and that these physiological patterns may support greater sensitivity to the positive effects of compassionate parenting on donation behavior. The current study focused on a follow-up assessment of these children at age 6. First, we examined the stability of individual differences in donation behavior and related parasympathetic nervous system (PNS) activity from age 4 to 6. Second, we examined associations between donation behavior and RSA at 6 years. Third, we examined whether the association between children’s RSA and donation behavior at age 6 varied depending on mothers’ compassionate love. We found low to modest stability in donation behavior and RSA reactivity from age 4 to 6. These findings provide preliminary evidence that stable individual differences in altruism, as reflected by generosity, and in some aspects of parasympathetic functioning during opportunities to be prosocial, emerge in childhood. In addition, we found that some of the same associations between donation behavior, RSA, and compassionate love that we previously observed in children at 4 years of age continued to be evident 2 years later at age 6. Greater decreases in RSA when given the opportunity to donate were associated with children donating more of their own resources which, in turn, were associated with greater RSA recovery after the task. Lastly, mothers’ compassionate love was positively associated with donation behavior in children who demonstrated stronger decreases in RSA during the task; compassionate parenting and RSA reactivity may serve as external and internal supports for prosociality that build on each other. Taken together, these findings contribute to the perspectives that individual differences in altruistic behaviors are intrinsically linked to healthy vagal flexibility, and that biopsychosocial approaches provide a useful framework for examining and understanding the environmental and physiological processes underlying these individual differences.

Observed Peer Competence Moderates Links between Children's Self-Regulation Skills and Academic Performance

The current study focuses on the relations between observed measures of children's self-regulation and academic achievement, as well as the extent to which observations of children's peer competence in preschool moderates these links. Data were drawn from 102 students (male = 48; M _age = 4.82 years, SD _age = 0.46 years) enrolled in pre-kindergarten classrooms. A series of linear path models was used to test study hypotheses, and the nature of significant interactions was elucidated by examining simple slopes and regions of significance. Children's self-regulation, but not peer competence, significantly predicted both reading and math performance assessed using the Woodcock Johnson III, β = .43, p < .001 and β = .39, p < .001, respectively. Tests of moderation effects revealed that the association between children's poor self-regulation and poor math performance, but not reading performance, β = -.28, p = .022 and β = -.11, p = .23, was negated for children with average to high peer competence. These results demonstrate the protective quality of peer competence for academic performance using observational methods collected in preschools.

Getting to the heart of childhood empathy: Relations with shyness and respiratory sinus arrhythmia

Although prior studies have found that shyness and empathy are inversely related and that well-regulated children tend to express empathic behaviors more often, little work has assessed combinations of these factors in predicting affective and cognitive empathy in early childhood. The authors examined relations among shyness, resting respiratory sinus arrhythmia (RSA), and observed affective and cognitive empathy in a sample of 130 typically developing children (M_age  = 63.5 months, SD = 12.2; 62 males). Shyness was assessed by observing children's behaviors during a self-presentation task, and this observed measure was then combined with a maternal report of children's temperamental shyness. Children's shyness predicted lower levels of both affective and cognitive responses to an experimenter feigning an injury. Resting RSA moderated the relation between children's shyness and observed empathy such that relatively higher shyness combined with lower RSA levels conferred the lowest levels of cognitive empathy. Children who were relatively low in shyness exhibited similar levels of cognitive empathy across different levels of RSA. However, this moderation was not found when predicting children's affective empathy. Our results suggest that not all shy children are alike in terms of their empathic behaviors: shy children who are physiologically dysregulated appear to have difficulties exploring and/or processing others' pain.

A latent change score approach to understanding dynamic autonomic coordination

Children's self-regulation is a core adaptive system in child development. Physiological indices of regulation, particularly the autonomic nervous system (ANS), have garnered increased attention as an informative level of analysis in regulation research. Cardiography supports the simultaneous examination of both ANS branches via measures of pre-ejection period (PEP) and respiratory sinus arrhythmia (RSA) as indicators of sympathetic and parasympathetic activity, respectively. However, despite their heavily intertwined functions, research examining autonomic coordination across sympathetic and parasympathetic systems is scarce. Moreover, extant efforts have favored static, mean level reactivity analyses, despite the dynamic nature of ANS regulation and the availability of analytic tools that can model these processes across time. This study drew on a sample of 198 six-year-old children from a diverse community sample (49.5% female, 43.9% Latinx) to examine dynamic autonomic coordination using bivariate latent change score modeling to evaluate bidirectional influences of sympathetic and parasympathetic activity over the course of a challenging puzzle completion task. Results indicated that children evidenced reciprocal sympathetic activation (i.e., PEP attenuation and RSA withdrawal) across the challenge task, and these regulatory responses were characterized by a temporally leading influence of PEP on lagging changes in RSA. The current findings contribute to our understanding of children's autonomic coordination while illustrating a novel analytic technique to advance ongoing efforts to understand the etiology and developmental significance of children's physiological self-regulation.

Vagal Tone Differences in Empathy Level Elicited by Different Emotions and a Co-Viewer

Empathy can bring different benefits depending on what kind of emotions people empathize with. For example, empathy with negative emotions can raise donations to charity while empathy with positive emotions can increase participation during remote education. However, few studies have focused on the physiological differences depending on what kind of emotions people empathize with. Furthermore, co-viewer can influence the elicitation of different levels of empathy, but this has been less discussed. Therefore, this study investigated vagal response differences according to each empathy factor level elicited by different emotions and co-viewer. Fifty-nine participants were asked to watch 4 videos and to evaluate subjective valence, arousal scores, and undertake an empathy questionnaire, which included cognitive, affective and identification empathy. Half of the participants watched the videos alone and the other half watched the videos with a co-viewer. Valence and arousal scores were categorized into three levels to figure out what kind of emotions they empathized with. Empathy level (high vs. low) was determined based on the self-report scores. Two-way MANOVA revealed an interaction effect of empathy level and emotions. High affective empathy level is associated with higher vagal response regardless of what kind of emotions they empathized with. However, vagal response differences in other empathy factor level showed a different pattern depending on what kind of emotions that participant empathized with. A high cognitive empathy level showed lower vagal responses when participants felt negative or positive valence. High identification level also showed increased cognitive burden when participants empathized with negative and neutral valence. The results implied that emotions and types of empathy should be considered when measuring empathic responses using vagal tone. Two-way MANOVA revealed empathic response differences between co-viewer condition and emotion. Participants with a co-viewer felt higher vagal responses and self-reporting empathy scores only when participants empathized with arousal. This implied that the effect of a co-viewer may impact on empathic responses only when participants felt higher emotional intensity.

Infant emotional responses to challenge predict empathic behavior in toddlerhood

Although emotional responses are theorized to be important in the development of empathy, findings regarding the prediction of early empathic behavior by infant behavioral and physiological responses are mixed. This study examined whether behavioral and physiological responses to mild emotional challenge (still face paradigm and car seat task) in 118 infants at age 6 months predicted empathic distress and empathic concern in response to an empathy-evoking task (i.e, experimenter's distress simulation) at age 20 months. Correlation analyses, corrected for sex and baseline levels of physiological arousal, showed that stronger physiological and behavioral responses to emotional challenge at age 6 months were positively related to observed empathic distress, but not empathic concern, at age 20 months. Linear regression analyses indicated that physiological and behavioral responses to challenge at 6 months independently predicted empathic distress at 20 months, which suggests an important role for both physiological and behavioral emotional responses in empathy development. In addition, curvilinear regression analyses showed quadratic associations between behavioral responses at 6 months, and empathic distress and empathic concern at 20 months, which indicates that moderate levels of behavioral responsivity predict the highest levels of empathic distress and empathic concern.

Physiological regulation and social-emotional processing in female carriers of the FMR1 premutation

The FMR1 gene is associated with a wide range of clinical and cognitive phenotypes, ranging from intellectual disability and autism symptoms in fragile X syndrome (caused by the FMR1 full mutation), to a more varied, and still poorly understood range of clinical and cognitive phenotypes among carriers of the gene in its premutation state. Because the FMR1 premutation is relatively common among women (as high as 1 in 150), investigations of its phenotypic impact could have broad implications for understanding gene-behavior relationships underlying complex human traits, with potential clinical implications. This study investigated physiological regulation measured by pupillary responses, along with fixation patterns while viewing facial expressions among women who carry the FMR1 premutation (PM group; n = 47), to examine whether the FMR1 gene may relate to physiological regulation, social-emotional functioning, and social language skills (where subclinical differences have been previously reported among PM carriers that resemble those documented in autism-related conditions). Relative to controls (n = 25), the PM group demonstrated atypical pupillary responses and fixation patterns, controlling for IQ. In the PM group, pupillary response and fixation patterns were related to social cognition, social language abilities, and FMR1-related variation. Results indicate a pattern of atypical attention allocation among women who carry the FMR1 PM that could reflect different emotion-processing strategies mediated by autonomic dysregulation and the FMR1 gene. These findings lend insight into the FMR1 gene's potential contributions to complex human traits such as social emotional processing and social language.

An inverted U-shaped relationship between heart rate deceleration and empathic emotions

Previous studies have shown that the high frequency component of heart rate variability is associated with empathic emotions (empathic concern and personal distress) negatively and quadratically-there is an inverted U-shaped relationship between tonic parasympathetic nervous system (PNS) activity and empathy. However, it is unclear whether the inverted U-shape also applies to the relationship between phasic PNS activity and empathic emotions. Therefore, the present study addressed this issue. Participants were asked to empathize with others' negative states (and neutral states as the control condition), followed by evaluating their own emotions. We measured the participants' cardiac activity during this task by electrocardiogram. Results revealed an inverted U-shaped relationship between heart rate deceleration, which reflects phasic PNS activity, and subjective personal distress and empathic concern. These results suggest that moderate levels of phasic PNS activity are more strongly associated with personal distress and empathic concern than low or high levels of PNS activity.

Inhibitory control moderates the quadratic association between resting respiratory sinus arrhythmia and prosocial behaviors in children

Resting respiratory sinus arrhythmia (RSA) is thought to be an important physiological correlate of prosocial behaviors. A negative quadratic association between resting RSA and prosocial behaviors has been found in recent studies. However, it remains unknown whether inhibitory control (IC), as an aspect of cognitive regulation, moderates this quadratic association. This issue was examined in the present study. One hundred and forty-eight children (81 girls, 54.7%) aged 7-8 years completed a go/no-go task to assess their IC, and the children's parents completed the Strengths and Difficulties Questionnaire-Chinese version (SDQ-CV) to assess children's prosocial behaviors. Resting RSA was calculated by electrocardiogram (ECG) data collected during a resting period in the laboratory. The results showed a significant quadratic association between resting RSA and children's prosocial behaviors. More importantly, IC had a significant moderating effect on the quadratic association between resting RSA and prosocial behaviors. Specifically, the quadratic effect of resting RSA on prosocial behaviors was observed only among children with low and average IC and disappeared in children with better IC. The findings suggest that IC interacts with resting RSA to contribute to prosocial behaviors in children. High levels of IC could attenuate the negative impact of high and low resting RSA on prosocial behaviors.

Autonomic nervous system functioning in early childhood: Responses to cognitive and negatively valenced emotional challenges

Although autonomic nervous system (ANS) functioning is "context-dependent," few studies examined children's normative sympathetic and parasympathetic autonomic responses to distinct challenges in early childhood years. Examining children's ANS responsivity to distinct challenges is important for understanding normative autonomic responses toward everyday life stressors and identifying paradigms that effectively elicit a "stress response." We examined children's (N = 278) sympathetic (preejection period [PEP]) and parasympathetic (respiratory sinus arrhythmia [RSA]) responses to cognitive (i.e., problem-solving and cognitive control) and negatively valenced emotional (i.e., blocked goal and unfairness) challenges in preschool, kindergarten, and grade 1. Children, on average, demonstrated parasympathetic inhibition (RSA withdrawal) in response to all challenges but the magnitude of these responses depended on the task. Children showed sympathetic activation (PEP shortening) toward the problem-solving task at each assessment and there was no sample-level change in the magnitude of this response over time. Children showed greater sympathetic responsivity toward the cognitive control task over time, with evidence for a sympathetic activation response only in grade 1. Children experienced sympathetic inhibition (PEP lengthening) toward the unfairness tasks but did not experience significant sympathetic responsivity toward the blocked goal tasks. Parasympathetic responsivity to most challenges were modestly stable but there was no stability in sympathetic responsivity across time.

Children's physiological reactivity in emotion contexts and prosocial behavior

INTRODUCTION

Building on prior evidence that prosocial behavior is related to the regulation of personal distress in difficult situations, and given that physiological regulation is a central contributor to effective emotion regulation, this investigation evaluated whether and how children's autonomic nervous system (ANS) reactivity during emotion challenges influenced later expressions of prosocial behavior.

METHODS

The current study utilized a diverse sample of school-aged children (N = 169; 47.9% female; 47.3% Latinx) to evaluate relations between children's parasympathetic (i.e., respiratory sinus arrhythmia; RSA) and sympathetic (i.e., pre-ejection period; PEP) reactivity in response to each of three film-elicited emotion challenges (i.e., sadness, happiness, and fear) at age 7 and both observed and parent-reported prosocial behavior one year later.

RESULTS

Children's parasympathetic reactivity to a film eliciting sadness evidenced a nonlinear relation with later prosocial sharing such that children who evidenced either RSA withdrawal or augmentation in response to the sad emotion challenge engaged in higher levels of prosocial behavior than children who evidenced relatively low or absent reactivity. Parasympathetic reactivity to films eliciting happiness or fear was not significantly related to later prosocial behavior. Likewise, children's sympathetic reactivity in response to the emotion challenges did not significantly predict later prosocial behavior.

CONCLUSIONS

These findings provide preliminary support for a nonlinear association between children's parasympathetic emotion reactivity and later prosocial behavior, and suggest that children's ANS regulation in sad emotion contexts may be particularly important for understanding prosocial development.

Probing curvilinear-by-linear interactions when the predictors are randomly sampled

Curvilinear effects and curvilinear-by-linear interactions are hypothesized, tested, and probed in various fields of the social and behavioral sciences. When such effects are found, researchers traditionally have tested the simple slope, and more recently have utilized the Johnson-Neyman technique, often at the values of the sample statistics of the predictor(s). Both approaches implicitly assume that values on the predictors have been sampled according to a fixed sampling plan. More typically in social and behavioral research, however, values on the predictors can be more appropriately considered as randomly sampled from a multivariate population distribution. I show analytically and through simulation that for regression models containing a curvilinear-by-linear interaction, fixed and random regression models produce the same estimates but different standard errors of the simple slope at values of the sample statistics of the predictors. When values on the predictors are randomly sampled, treating them as fixed when testing the simple slope or generating conditional Johnson-Neyman confidence bands at values of the sample statistics of the predictors can lead to inflated Type I error rates and inaccurate coverage rates. Recommendations for researchers are provided, and directions for future research are discussed.

Respiratory sinus arrhythmia and prosociality in childhood: Evidence for a quadratic effect

Research investigating the link between the parasympathetic nervous system (PNS) and prosociality in childhood has yielded inconsistent findings. This relation has mainly been conceptualized as linear, however, the broader physiological literature suggests that children's physiological arousal and task performance may be related in an inverted U-shaped fashion-with peak performance at moderate levels of arousal. Therefore, we tested whether resting respiratory sinus arrhythmia (RSA)-a dispositional indicator of PNS activity-was quadratically related to child- and caregiver-reported sympathy and prosocial behaviors in an ethnically diverse sample of 4- and 8-year-olds (N = 300). We found a quadratic inverted U-shaped association between resting RSA and child-reported sympathy and prosocial behavior in 8-year-olds, whereas no consistent findings emerged for 4-year-olds. Therefore, moderate resting RSA in middle childhood may facilitate sympathy and prosocial behaviors. Dispositional over- or under-arousal of the PNS may impair children's ability to attend and respond to the distress of others by middle childhood.

Resting heart rate variability is negatively associated with mirror neuron and limbic response to emotional faces

Whether neurovisceral integration, reflected by resting high-frequency heart rate variability (HRV), constrains or facilitates neural reactivity to other people's emotions is unclear. We assessed the relation between resting HRV and neural activation when observing and imitating emotional faces. We focused on brain regions implicated in sensorimotor resonance, salience detection and arousal. We used electrocardiogram data to compute resting HRV. Resting HRV measures were negatively correlated with activation in a portion of the inferior frontal gyrus showing mirror neuron properties, the insula and the amygdala in response to observation, but not imitation, of emotional faces. Thus, resting HRV appears to be linked to sensitivity to others' emotional cues, both in terms of the tendency to map others' emotional facial expressions onto one's own motor system and to rapidly detect and mark others' emotions as salient events. Resting HRV may reflect, in part, a threshold for increased processing of others' emotional cues.

The mediating effect of empathy in the quadratic relationship between children's resting RSA and sharing behavior

The present study examined the mediating role of empathy in the quadratic relationship (an inverted U-shaped curve) between resting RSA and sharing behavior in 7- to 8-year-old children. Sharing behavior was measured using children's allocation of resources in the dictator game; the Griffith Empathy Scale-Chinese version was used to assess children's empathy. Resting RSA was calculated by electrocardiogram (ECG) data collected during a resting period in the laboratory. The results demonstrated a significant mediating effect of empathy in the quadratic association between resting RSA and sharing behavior. Specifically, moderate resting RSA was related to greater empathy and then contributed to more sharing behavior, while high and low resting RSA had a negative impact on empathy, which reduced the children's sharing behavior. The present study is the first to investigate the mediating role of empathy in the quadratic relationship between resting RSA and sharing behaviors. Accordingly, this study contributes to a better understanding of the psychological mechanisms that underlie the quadratic vagal tone-prosociality relationship.

Low vagal tone in two rat models of psychopathology involving high or low corticosterone stress responses

The two stress-responsive physiological systems, autonomic nervous system (ANS) and hypothalamus-pituitary-adrenal (HPA) axis exert complementary and interrelated actions in the organism. Individuals that suffer stress-related psychopathologies frequently present simultaneous alterations -i.e., either low or high- responsiveness- in both systems. However, there is scarce evidence establishing whether a priori alterations in these systems -i.e., independent of previous stress exposure- may predispose to the development of psychopathologies possibly due to the lack of animal models simultaneously involving aberrant HPA and SNS responses. In this study, we describe two animal models selectively bred according to their differential (either high, 'High', or low, 'Low') glucocorticoid responsiveness to stress, in comparison to a third line of rats that displays intermediate ('Inter') glucocorticoid responses. The two extreme lines may be considered distinct models of psychopathology; the High line representing a model of constitutive mood alterations while the Low line a model of vulnerability to develop stress-induced psychopathologies. We recorded the electrocardiogram in rats from the three lines and quantified heart rate variability and vagal tone indexes during rest and stress challenges. Rats from both High and Low lines displayed higher heart rate and lower basal vagal tone than the Inter group, both at resting and following stress exposure. Specific pharmacological manipulations probing the relative contribution of sympathetic and parasympathetic components on HR modulation confirmed a relative lower vagal tone in High and Low lines and discarded differences in the sympathetic regulation of heart rate between the lines. Therefore, the two genetically-selected High and Low glucocorticoid rat lines emerge as two valuable preclinical models of psychopathology involving two key risk factors for psychiatric and cardiovascular disorders, namely dysregulations in the HPA axis and cardiac vagal functioning.

A case study of two adolescent-parent pairs describing the association between vagal tone and social-emotional adjustment during a Positive Cognitive Behaviour Therapy Programme

OBJECTIVE

A case study describing the association between vagal tone and social-emotional adaptation in two distressed adolescent-parent (A-P) pairs during a Positive Cognitive Behaviour Therapy Programme (P-CBTP).

METHODS

Two A-P pairs completed a P-CBTP with pre- and post-intervention biosocial-emotional assessments; weekly training sessions over 7 weeks to develop individual strengths, new adaptive cognitions, positive discipline skills, optimism and knowledge on age-appropriate developmental expressions; augmented by moderate physical activity. Resting vagal tone and vagal reactivity were assessed by time-domain measures of vagal activity (RMSSD).

RESULTS

Social-emotional adjustment improved in all A-P pairs. Resting vagal tone increased over the intervention period, from low-to-low-normal towards average-for-normal in three subjects. The fourth individual had excessive pre-intervention resting vagal tone that declined in the direction of normal over the intervention period. Vagal reactivity in response to orthostatic stress remained the same pre- to post-intervention.

CONCLUSIONS

Changes in resting vagal tone demonstrated improvements in psychological functioning in all four subjects over the period of intervention. Results supported the view of the association between vagal tone and mental health not being an absolute positive relationship, but that low, as well as excessive, vagal tone may be maladaptive. Indications are that the same may apply to vagal reactivity to psychological stress. More studies need to examine the association between resting vagal tone and emotion regulation in A-P relationships during P-CBTP, keeping in mind that a linear relationship cannot summarily be expected in population studies.