Still-Face Paradigm Research Articles

Stress responses of infants and mothers to a still-face paradigm after traumatic childbirth

IntroductionOne-third of women experience childbirth as traumatic and some develop symptoms of childbirth-related posttraumatic stress symptoms (CB-PTSS). Whether CB-PTSS negatively impact on physiological and psychological stress responses in mothers and their offspring and whether they are associated with mother-infant synchrony is not clear. This study aimed to investigate stress responses of (1) mothers with CB-PTSS, (2) of their infant, and (3) the physiological mother-child-synchrony at six months postpartum. MethodPsychophysiological (cortisol and vagal tone) and psychological stress responses of mothers and infant’s (n=31 dyads) from the Swiss TrAumatic biRth Trial (NCT03576586) were assessed during a face-to-face still-face paradigm (FFSF-R). ResultsThere was a significant time effect in maternal stress responses for salivary cortisol, vagal tone, and for maternal subjective stress. As expected, mothers’ subjective stress increased during the stress task and mothers vagal tone changed during the first stressful period but not during the second, whereas cortisol unexpectedly decreased over the FFSF-R. Infant negative mood increased over the experiment, but there were no physiological changes. However, a significant interaction effect for mother-infant synchrony during the second reunion period of the FFSF-R was found. ConclusionAlthough mothers and their infants were subjectively stressed, they showed only limited physiological stress responses.

Understanding allostasis: Early-life self-regulation involves both up- and down-regulation of arousal.

Optimal performance lies at intermediate autonomic arousal, but no previous research has examined whether the emergence of endogenous control associates with changes in children's up-regulation from hypo-arousal, as well as down-regulation from hyper-arousal. We used wearables to take day-long recordings from N = 58, 12-month-olds (60% white/58% female); and, in the same infants, we measured self-regulation in the lab with a still-face paradigm. Overall, our findings suggest that infants who showed more self-regulatory behaviors in the lab were more likely to actively change their behaviors in home settings moment-by-moment "on the fly" following changes in autonomic arousal, and that these changes result in up- as well as down-regulation. Implications for the role of atypical self-regulation in later psychopathology are discussed.

Understanding emotion dysregulation from infancy to toddlerhood with a multilevel perspective: The buffering effect of maternal sensitivity.

Challenges with childhood emotion regulation may have origins in infancy and forecast later social and cognitive developmental delays, academic difficulties, and psychopathology. This study tested whether markers of emotion dysregulation in infancy predict emotion dysregulation in toddlerhood, and whether those associations depended on maternal sensitivity. When children (N = 111) were 7 months, baseline respiratory sinus arrhythmia (RSA), RSA withdrawal, and distress were collected during the Still Face Paradigm (SFP). Mothers' reports of infant regulation and orientation and maternal sensitivity were also collected at that time. Mothers' reports of toddlers' dysregulation were collected at 18 months. A set of hierarchical regressions indicated that low baseline RSA and less change in RSA from baseline to stressor predicted greater dysregulation at 18 months, but only for infants who experienced low maternal sensitivity. Baseline RSA and RSA withdrawal were not significantly associated with later dysregulation for infants with highly sensitive mothers. Infants who exhibited low distress during the SFP and who had lower regulatory and orienting abilities at 7 months had higher dysregulation at 18 months regardless of maternal sensitivity. Altogether, these results suggest that risk for dysregulation in toddlerhood has biobehavioral origins in infancy but may be buffered by sensitive caregiving.

Infant attachment does not depend on neonatal amygdala and hippocampal structure and connectivity

Infant attachment is an antecedent of later socioemotional abilities, which can be adversely affected by preterm birth. The structural integrity of amygdalae and hippocampi may subserve attachment in infancy. We aimed to investigate associations between neonatal amygdalae and hippocampi structure and their whole-brain connections and attachment behaviours at nine months of age in a sample of infants enriched for preterm birth. In 133 neonates (median gestational age 32 weeks, range 22.14–42.14), we calculated measures of amygdala and hippocampal structure (volume, fractional anisotropy, mean diffusivity, neurite dispersion index, orientation dispersion index) and structural connectivity, and coded attachment behaviours (distress, fretfulness, attentiveness to caregiver) from responses to the Still-Face Paradigm at nine months. After multiple comparisons correction, there were no significant associations between neonatal amygdala or hippocampal structure and structural connectivity and attachment behaviours: standardised β values − 0.23 to 0.18, adjusted p-values > 0.40. Findings indicate that the neural basis of infant attachment in term and preterm infants is not contingent on the structure or connectivity of the amygdalae and hippocampi in the neonatal period, which implies that it is more widely distributed in early life and or that network specialisation takes place in the months after hospital discharge.

Examining the implications of contextual stress and maternal sensitivity for infants’ cortisol responses to the still face paradigm

Infants’ hypothalamic-pituitary-adrenocortical (HPA) axis responses to acute stressors are theorized to be shaped by parents’ sensitive responsiveness to infants’ cues. The strength and direction of the association between maternal sensitivity and infants’ HPA responses may depend on the context in which maternal sensitivity is observed and on broader environmental sources of stress and support. In this preregistered study, we used data from 105 mothers and their 7-month-old infants to examine whether two empirically identified forms of contextual stress—poor maternal psychosocial wellbeing and family socioeconomic hardship—moderate the association between maternal sensitivity and infants’ cortisol responses to the Still-Face Paradigm (SFP). Results indicated that maternal sensitivity during the free play and family socioeconomic hardship interacted to predict infants’ cortisol responses to the SFP. Specifically, maternal sensitivity during this non-distressing interaction was negatively associated with cortisol responses only among infants whose mothers were experiencing relatively high socioeconomic hardship. Exploratory analyses revealed that poor maternal psychosocial wellbeing was positively associated with overall infant cortisol production during the SFP. Altogether, these findings suggest that experiences within early parent-infant attachment relationships and sources of contextual stress work together to shape infant HPA axis activity.

It’s You and Me: Infants’ cross-modal communicative signals and mother-infant interactive behavior predict infant regulatory patterns in the still-face paradigm at 3 months

Infant regulatory behavior develops since birth and impacts their early social interactions. Infants differ in the relative coherence and incoherence of their cross-modal communicative signals during en-face infant-caregiver interactions. We expand this research by evaluating whether different infant regulatory patterns observed during the Face-to-Face Still-Face (FFSF) at 3 months are associated with the coherence or incoherence of infants’ cross-modal communicative behaviors during en-face interactions or with multiple dimensions of mother-infant interactive behavior during free-play. Analyses were based on data collected from 100 mother-infant dyads from urban, working- and middle-class backgrounds in Portugal who were videotaped during the FFSF and free play at 3 months. Results confirm that infants’ different regulatory behavior patterns in the FFSF at 3 months are associated with the coherence and incoherence of their cross-modal interactive behaviors and specific aspects of mother-infant interaction. Infants with a Social-Positive oriented regulatory pattern during the FFSF displayed more coherent and less incoherent communicative behaviors with their mothers and were more cooperative during free play. In turn, their mothers were more sensitive. Our findings support the perspective that infants' regulatory behavior strategies in the context of caregiver regulatory support and sensitivity are likely to increase dyadic correspondence and infant ability to engage with the world.

The correlation between brain structure characteristics and emotion regulation ability in children at high risk of autism spectrum disorder.

As indicated by longitudinal observation, autism has difficulty controlling emotions to a certain extent in early childhood, and most children's emotional and behavioral problems are further aggravated with the growth of age. This study aimed at exploring the correlation between white matter and white matter fiber bundle connectivity characteristics and their emotional regulation ability in children with autism using machine learning methods, which can lay an empirical basis for early clinical intervention of autism. Fifty-five high risk of autism spectrum disorder (HR-ASD) children and 52 typical development (TD) children were selected to complete the skull 3D-T1 structure and diffusion tensor imaging (DTI). The emotional regulation ability of the two groups was compared using the still-face paradigm (SFP). The classification and regression models of white matter characteristics and white matter fiber bundle connections of emotion regulation ability in the HR-ASD group were built based on the machine learning method. The volume of the right amygdala (R2 = 0.245) and the volume of the right hippocampus (R2 = 0.197) affected constructive emotion regulation strategies. FA (R2 = 0.32) and MD (R2 = 0.34) had the predictive effect on self-stimulating behaviour. White matter fiber bundle connection predicted constructive regulation strategies (positive edging R2 = 0.333, negative edging R2 = 0.334) and mother-seeking behaviors (positive edging R2 = 0.667, negative edging R2 = 0.363). The emotional regulation ability of HR-ASD children is significantly correlated with the connections of multiple white matter fiber bundles, which is a potential neuro-biomarker of emotional regulation ability.

The association of maternal-infant interactive behavior, dyadic frontal alpha asymmetry, and maternal anxiety in a smartphone-adapted still face paradigm

Mother-infant interactions form a strong basis for emotion regulation development in infants. These interactions can be affected by various factors, including maternal postnatal anxiety. Electroencephalography (EEG) hyperscanning allows for simultaneous assessment of mother-infant brain-to-behavior association during stressful events, such as the still-face paradigm (SFP). This study aimed at investigating dyadic interactive behavior and brain-to-behavior association across SFP and identifying neural correlates of mother-infant interactions in the context of maternal postnatal anxiety. We measured frontal alpha asymmetry (FAA), a physiological correlate of emotion regulation and a potential marker of risk for psychopathology. To emulate real-life interactions, EEG and behavioral data were collected from 38 mother-infant dyads during a smartphone-adapted dual-SFP. Although the behavioral data showed a clear still-face effect for the smartphone-adapted SFP, this was not reflected in the infant or maternal FAA. Brain-to-behavior data showed higher infant negative affect being associated with more infant leftward FAA during the still-face episodes. Finally, mothers with higher postnatal anxiety showed more right FAA during the first still-face episode, suggesting negative affectivity and a need to withdraw from the situation. Our results form a baseline for further research assessing the effects of maternal postnatal anxiety on infants’ FAA and dyadic interactive behavior.

Predicting attachment in Portuguese infants born very or extremely preterm: Understanding the roles of infant regulatory behavior, maternal sensitivity, and risk factors.

A growing body of research shows that early attachment relationships are foundational for children's later developmental and psychosocial outcomes. However, findings are mixed regarding whether preterm birth predicts later attachment, but insecurity is generally more prevalent among infants at higher medical and/or social/familial risk. This longitudinal study aimed to identify specific relational, familial/demographic, and perinatal predictors of attachment in a sample of 63 Portuguese infants born very or extremely preterm (VEPT,<32 gestational weeks) and their mothers from diverse socioeconomic backgrounds. One-third of the mothers had social/family risk factors (e.g., single parent, immigrant, unemployed, low education, and/or low income). At 3 months (corrected age), dyads were observed during social interaction in the Face-to-Face Still-Face paradigm (FFSF) and during free play. At 12 months, mother-infant dyads were observed in Ainsworth's Strange Situation. Over half (58.7%) of the infants were classified as insecurely attached. Social-Positive Oriented regulatory behavior pattern, higher maternal sensitivity, higher infant cooperation during free play, number of siblings and an absence of social/family risk factors were associated with attachment security. Perinatal variables were unrelated to attachment. Findings indicate that both relational and social contextual factors contribute to attachment in this biologically vulnerable sample.

Pregnant women's autonomic responses to an infant cry predict young infants' behavioral avoidance during the still-face paradigm.

Research suggests that women's autonomic nervous system responses to infant cries capture processes that affect their parenting behaviors. The aim of this study was to build on prior work by testing whether pregnant women's autonomic responses to an unfamiliar infant crying also predict their infants' emerging regulation abilities. Participants included 97 women in their third trimester of pregnancy, located in the United States. Most participants identified as White/non-Hispanic (48%) or Hispanic (30%), their mean age was approximately 30 years, and the modal family income was $40,000-$79,999. Pregnant women's respiratory sinus arrhythmia (RSA) and skin conductance levels (SCL)-which are thought to capture emotional engagement and behavioral inhibition, respectively-were measured while the women watched a relaxing video and a video of an unfamiliar infant crying. Approximately 7 months later, women and their infants completed the still-face paradigm (SFP). Infants' avoidance and resistance behaviors during the SFP reunions were rated. Pregnant women's RSA and SCL responses to the infant cry video uniquely predicted infants' avoidance (but not resistance) during the SFP. Infants displayed higher levels of avoidance when their mothers exhibited lower levels of RSA reactivity or when their mothers exhibited higher levels of SCL activity in response to the infant cry video. Maternal sensitivity during mother-infant free-play interactions did not mediate the associations between pregnant women's autonomic responses to the cry video and infants' avoidant behavior during the SFP. Discussion focuses on potential mechanisms underlying associations between pregnant women's autonomic responses to infant distress and infants' socioemotional development. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Effects of prenatal opioid exposure on infant sympathetic and parasympathetic nervous system activity.

Prenatal opioid exposure has been associated with developmental problems, including autonomic nervous system dysregulation. However, little is known about the effects of prenatal opioid exposure on the autonomic nervous system beyond the first days of life, particularly across both the parasympathetic and sympathetic branches, and when accounting for exposure to other substances. The present study examined the effects of prenatal exposure to opioid agonist therapy (OAT, e.g., methadone) and other opioids on infant autonomic nervous system activity at rest and in response to a social stressor (the Still-Face Paradigm) at six months among 86 infants varying in prenatal opioid and other substance exposure. Results indicated that OAT and other opioids have unique effects on the developing autonomic nervous system that may further depend on subtype (i.e., methadone versus buprenorphine) and timing in gestation. Results are discussed in the context of theoretical models of the developing stress response system.

Linking maternal disrupted interaction and infant limbic volumes: The role of infant cortisol output

Despite a large animal literature documenting the role of low maternal nurturance and elevated glucocorticoid production on offspring limbic development, these pathways have not yet been assessed during human infancy. Informed by animal models, the present study examined whether 1) maternal disrupted interaction is related to infant cortisol levels, 2) infant cortisol levels are associated with infant limbic volumes, and 3) infant cortisol levels mediate associations between maternal disrupted interaction and infant limbic volumes. Participants included 57 mother-infant dyads. Infant saliva was measured at one time point before and two time points after the Still-Face Paradigm (SFP) at age 4 months. Five aspects of maternal disrupted interaction were coded during the SFP reunion episode. Between 4 and 25 months (M age = 11.74 months, SD = 6.12), under natural sleep, infants completed an MRI. Amygdala and hippocampal volumes were calculated via automated segmentation. Results indicated that 1) maternal disrupted interaction, and specifically disoriented interaction, with the infant was associated with higher infant salivary cortisol (AUCg) levels during the SFP, 2) higher infant AUCg was related to enlarged bilateral amygdala and hippocampal volumes, and 3) infant AUCg mediated the relation between maternal disrupted interaction and infant amygdala and hippocampal volumes. Findings are consistent with controlled animal studies and provide evidence of a link between increased cortisol levels and enlarged limbic volumes in human infants. Results further suggest that established interventions to decrease maternal disrupted interaction could impact both infant cortisol levels and infant limbic volumes.

Negative versus withdrawn maternal behavior: Differential associations with infant gray and white matter during the first 2 years of life.

Distinct neural effects of threat versus deprivation emerge by childhood, but little data are available in infancy. Withdrawn versus negative parenting may represent dimensionalized indices of early deprivation versus early threat, but no studies have assessed neural correlates of withdrawn versus negative parenting in infancy. The objective of this study was to separately assess the links of maternal withdrawal and maternal negative/inappropriate interaction with infant gray matter volume (GMV), white matter volume (WMV), amygdala, and hippocampal volume. Participants included 57 mother-infant dyads. Withdrawn and negative/inappropriate aspects of maternal behavior were coded from the Still-Face Paradigm at four months infant age. Between 4 and 24 months (M age = 12.28 months, SD = 5.99), during natural sleep, infants completed an MRI using a 3.0 T Siemens scanner. GMV, WMV, amygdala, and hippocampal volumes were extracted via automated segmentation. Diffusion weighted imaging volumetric data were also generated for major white matter tracts. Maternal withdrawal was associated with lower infant GMV. Negative/inappropriate interaction was associated with lower overall WMV. Age did not moderate these effects. Maternal withdrawal was further associated with reduced right hippocampal volume at older ages. Exploratory analyses of white matter tracts found that negative/inappropriate maternal behavior was specifically associated with reduced volume in the ventral language network. Results suggest that quality of day-to-day parenting is related to infant brain volumes during the first two years of life, with distinct aspects of interaction associated with distinct neural effects.

Associations between infant amygdala functional connectivity and social engagement following a stressor: A preliminary investigation.

Functional architecture of the infant brain, especially functional connectivity (FC) within the amygdala network and between the amygdala and other networks (i.e., default-mode [DMN] and salience [SAL] networks), provides a neural basis for infant socioemotional functioning. Yet, little is known about the extent to which early within- and between-network amygdala FC are related to infant stress recovery across the first year of life. In this study, we examined associations between amygdala FC (i.e., within-network amygdala connectivity, and between-network amygdala connectivity with the DMN and SAL) at 3 months and infant recovery from a mild social stressor at 3, 6 and 9 months. At 3 months, thirty-five infants (13 girls) underwent resting-state functional magnetic resonance imaging during natural sleep. Infants and their mothers completed the still-face paradigm at 3, 6, and 9 months, and infant stress recovery was assessed at each time point as the proportion of infant social engagement during the reunion episode. Bivariate correlations indicated that greater positive within-network amygdala FC and greater positive amygdala-SAL FC, but not amygdala-DMN FC, at 3 months predicted lower levels of stress recovery at 3 and 6 months, but were nonsignificant at 9 months. These findings provide preliminary evidence that early functional synchronization within the amygdala network, as well as segregation between the amygdala and the SAL, may contribute to infant stress recovery in the context of infant-mother interaction.

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.

Functional neural network connectivity at 3months predicts infant-mother dyadic flexibility during play at 6months.

Early functioning of neural networks likely underlies the flexible switching between internal and external orientation and may be key to the infant's ability to effectively engage in social interactions. To test this hypothesis, we examined the association between infants' neural networks at 3months and infant-mother dyadic flexibility (denoting the structural variability of their interaction dynamics) at 3, 6, and 9months. Participants included thirty-five infants (37% girls) and their mothers (87% White). At 3months, infants participated in a resting-state functional magnetic resonance imaging session, and functional connectivity (FC) within the default mode (DMN) and salience (SN) networks, as well as DMN-SN internetwork FC, were derived using a seed-based approach. When infants were 3, 6, and 9months, infant-mother dyads completed the Still-Face Paradigm where their individual engagement behaviors were observed and used to quantify dyadic flexibility using state space analysis. Results revealed that greater within-DMN FC, within-SN FC, and DMN-SN anticorrelation at 3months predicted greater dyadic flexibility at 6months, but not at 3 and 9months. Findings suggest that early synchronization and interaction between neural networks underlying introspection and salience detection may support infants' flexible social interactions as they become increasingly active and engaged social partners.

Interactive effects of maternal physiological arousal and regulation on maternal sensitivity: Replication and extension in an independent sample.

This study examined the extent to which mothers' physiological arousal (i.e., skin conductance level [SCL] augmentation) and regulation (i.e., respiratory sinus arrhythmia [RSA] withdrawal) interacted to predict subsequent maternal sensitivity. Mothers' (N=176) SCL and RSA were measured prenatally during a resting baseline and while watching videos of crying infants. Maternal sensitivity was observed during a free-play task and the still-face paradigm when their infants were 2months old. The results demonstrated that higher SCL augmentation but not RSA withdrawal predicted more sensitive maternal behaviors as a main effect. Additionally, SCL augmentation and RSA withdrawal interacted, such that well-regulated maternal arousal was associated with greater maternal sensitivity at 2months. Further, the interaction between SCL and RSA was only significant for the negative dimensions of maternal behavior used to derive the measure of maternal sensitivity (i.e., detachment and negative regard) suggesting that well-regulated arousal is particularly important for inhibiting the tendency to engage in negative maternal behaviors. The results replicate findings from mothers in previous studies and demonstrate that the interactive effects of SCL and RSA in relation to parenting outcomes are not sample specific. Considering joint effects of physiological responding across multiple biological systems may enhance understanding of the antecedents of sensitive maternal behavior.

Childbirth-related post-traumatic stress disorder symptoms and mother–infant neurophysiological and behavioral co-regulation during dyadic interaction: study protocol

BackgroundMother’s childbirth-related posttraumatic stress disorder (PTSD) symptoms have a negative impact on mother and infant’s behaviors during dyadic interactions which may increase mother–infant neurophysiological and behavioral co-regulation difficulties, leading to dysregulated mother–infant interactions. This study was specifically designed to analyze: (1) the sociodemographic and obstetric factors associated with mother’s childbirth-related PTSD symptoms; (2) mother–infant neurophysiological functioning and behavioral co-regulation during dyadic interaction; (3) the impact of mother’s childbirth-related PTSD symptoms on neurophysiological and behavioral mother–infant co-regulation during dyadic interaction; (4) the moderator role of previous trauma on the impact of mother’s childbirth-related PTSD symptoms on neurophysiological and behavioral mother–infant co-regulation during dyadic interaction; and (5) the moderator role of comorbid symptoms of anxiety and depression on the impact of mother’s childbirth-related PTSD symptoms on neurophysiological and behavioral mother–infant co-regulation during dyadic interaction.MethodsAt least 250 mothers will be contacted in order to account for refusals and dropouts and guarantee at least 100 participating mother–infant dyads with all the assessment waves completed. The study has a longitudinal design with three assessment waves: (1) 1–3 days postpartum, (2) 8 weeks postpartum, and (3) 22 weeks postpartum. Between 1 and 3 days postpartum, mothers will report on-site on their sociodemographic and obstetric characteristics. At 8 weeks postpartum, mothers will complete online self-reported measures of birth trauma, previous trauma, childbirth-related PTSD, anxiety, and depressive symptoms. At 22 weeks postpartum, mothers will complete online self-reported measures of childbirth-related PTSD, anxiety, and depressive symptoms. Mothers and infants will then be home-visited to observe and record their neurophysiological, neuroimaging and behavioral data during dyadic interactions using the Still-face Paradigm. Activation patterns in the prefrontal cortices of mother and infant will be recorded simultaneously using hyperscanning acquisition devices. Unadjusted and adjusted multilevel linear regression models will be performed to analyze objectives 1 to 3. Moderation models will be performed to analyze objectives 4 and 5.DiscussionData from this study will inform psychological interventions targeting mother–infant interaction, co-regulation, and infant development. Moreover, these results can contribute to designing effective screenings to identify mothers at risk of perinatal mental health problems and those who may need specialized perinatal mental health care.

The Still-Face Paradigm: Training Model for Relational Health.

The Still-Face Paradigm: Training Model for Relational Health.

Dynamics of mother-infant parasympathetic regulation during face-to-face interaction: The role of maternal emotion dysregulation.

The dynamics of parent-infant physiology are essential for understanding how biological substrates of emotion regulation are organized during infancy. Although parent-infant physiological processes are dyadic in nature, research is limited in understanding how one person's physiological responses predict one's own and as well as the other person's responses in the subsequent moment. In this study, we examined mother-infant respiratory sinus arrhythmia (RSA) dynamics during the Still-Face Paradigm (SFP) among 106 mothers (Mage =29.54) and their 7-month-old infants (55 males). Given mothers' role in shaping dyadic interactions with their infant, we also tested how mothers' self-reported emotion dysregulation (measured via the Difficulties in Emotion Regulation Scale) associated with these dynamics. Results showed that both mothers' and infants' RSA tended to return to their respective homeostatic points (i.e., exhibited return strength) during each SFP episode, indicating stability in RSA for mother-infant dyads. Significant shifts in mother and infant RSA return strength were observed across SFP episodes, highlighting the role of contextual demands on each individual's physiological dynamics. Mother-infant RSA dynamics varied as a function of maternal self-reported emotion dysregulation. Specifically, RSA levels of infants with more dysregulated mothers had a weaker tendency to return to homeostasis during the Reunion episode and were less affected by their mothers' RSA during the Still-Face and Reunion episodes of the SFP, suggesting a less effective coregulatory influence. Our findings have implications for the intergenerational transmission of emotion dysregulation via mother-infant physiological dynamics.