Trinh Nguyen

Caregivers often face stressful multi-tasking situations in which household- or work-related tasks compete with engaging with their young child. Caregivers’ experiences of stress can affect how they interact with their children and may also be transmitted to the child. This “stress contagion” may be particularly pronounced with caregivers who have difficulties in regulating stress responses. In the current study, we examined how inducing stress in 62 mothers shaped the dyadic interaction (expression of facial affect and cardiovascular activity) with their 6-38 months-old children, and how stress-induced changes varied depending on self-reported maternal emotion regulation difficulties and child age. Mothers’ and children’s positive and negative facial affect, inter-beat intervals (IBIs) and respiratory sinus arrhythmia (RSA), as well as synchrony in each measure, were compared between two-minute face-to-face interactions before and after a stress induction in the mother (pre- and post-stress). Maternal stress impacted the dyad differently depending on the child’s age. In interactions with younger children, both mothers and children showed less positive facial expressions and were less synchronized in their expressions post- versus pre-stress. Older children, in contrast, showed stronger physiological arousal (i.e., decrease in IBIs and RSA), but more positive facial expressions post-stress. In addition, mothers with more emotion regulation difficulties expressed more negative affect, and their heart rates were less synchronized with their children’s post- versus pre-stress. Both child age and mothers’ regulatory abilities are thus shaping the impact of acute maternal stress on mother-child interaction quality and should be considered in interventions on parental stress

The preschool years are crucial for school readiness, with the child-parent attachment relationship providing a foundational context for skill acquisition as part of this transition. Advances in social neuroscience suggest that interpersonal neural synchrony (INS) represents a valuable index of interaction and relationship quality. We examined whether parent-child INS during a parent-guided learning task was associated with observed parental interaction behavior and narrative child attachment representations. INS in bilateral frontal and temporoparietal cortex was assessed using functional near-infrared spectroscopy (fNIRS) hyperscanning in ninety-three parents (51 fathers) and their biological children (aged 5-6 years, 48 girls) while parents guided children through cognitive exercises. Parental interaction behavior was assessed using video-coded NICHD sensitivity scales, and children’s attachment representations were indexed by narrative coherence using the Picture Story Stem Battery (PSSB). Results revealed specific region-dependent functional patterns. A positive correlation between parental respect for autonomy and quality of assistance with bilateral prefrontal INS possibly reflecting cognitive scaffolding. Furthermore, INS in the left prefrontal cortex positively correlated with child task performance and mediated the relationship between parental assistance and task success. In contrast, temporoparietal INS, particularly in mother-child dyads, possibly reflected relational and regulatory processes. While child attachment security positively correlated with right temporoparietal INS, maternal hostility negatively correlated with bilateral temporoparietal INS. Taken together, our findings suggest that INS in the prefrontal and temporoparietal cortex may serve as a differential neurobiological correlate of dyadic coordination, possibly capturing both the relational quality of the child-parent attachment bond and the efficacy of parental scaffolding in supporting early learning.

Humans across cultures not only share the ability to recognise music but also respond to it through movement. While the sensory encoding of music is well-studied, when and how infants naturally start moving to music is largely unexplored. This study simultaneously investigates infants’ neural (auditory) responses and spontaneous movements to music during the first postnatal year. Neural activity (EEG) and body kinematics (markerless pose estimation) were recorded from 79 infants (aged 3, 6, and 12 months) listening to refrains of children’s music, along with shuffled, high-pitched, and low-pitched versions of the same songs. Neural data revealed that, across all ages, infants exhibit enhanced auditory responses to music compared to shuffled music, indicating that auditory encoding of music emerges early in development. Movement data revealed a different outcome. While coarse auditory-motor coupling is present at all ages, more complex structured movement patterns emerge in response to music only by 12 months. Notably, no age group demonstrated evidence of coordinated movements to music. Additionally, enhanced auditory responses to high vs low pitch were only evident at 6 months, while infants’ movements were better predicted by high-pitched compared to low-pitched music at all ages. This study provides initial insights into how the developing brain gradually transforms music into spontaneous movements of increasing complexity.

Humans across cultures not only share the ability to recognise music but also respond to it through movement. While the sensory encoding of music is well-studied, when and how infants naturally start moving to music is largely unexplored. This study simultaneously investigates infants’ neural (auditory) responses and spontaneous movements to music during the first postnatal year. Neural activity (EEG) and body kinematics (markerless pose estimation) were recorded from 79 infants (aged 3, 6, and 12 months) listening to refrains of children’s music, along with shuffled, high-pitched, and low-pitched versions of the same songs. Neural data revealed that, across all ages, infants exhibit enhanced auditory responses to music compared to shuffled music, indicating that auditory encoding of music emerges early in development. Movement data revealed a different outcome. While coarse auditory-motor coupling is present at all ages, more complex structured movement patterns emerge in response to music only by 12 months. Notably, no age group demonstrated evidence of coordinated movements to music. Additionally, enhanced auditory responses to high vs low pitch were only evident at 6 months, while infants’ movements were better predicted by high-pitched compared to low-pitched music at all ages. This study provides initial insights into how the developing brain gradually transforms music into spontaneous movements of increasing complexity.

The development of self-regulation is a foundational milestone of early childhood, predicting outcomes from future academic success to mental health throughout the lifespan. Accumulating behavioral research suggests that self-regulation is not innate but socially constructed, originating in "co-regulatory" interactions where caregivers modulate a child's arousal and attention. However, the neural mechanisms supporting the transition from external regulation to internal capacity remain poorly understood. This opinion piece proposes that interpersonal neural synchrony (INS), the temporal alignment of brain activity between interacting partners, serves as a critical biomarker of this transition. We synthesize evidence linking INS to both co-regulation and to self-regulation strategies, arguing that INS may serve as the neural bridge that facilitates the transmission of regulatory competence from dyadic to independent regulation. We identify critical research gaps and propose a framework in which INS is no longer understood solely as a marker of interpersonal dependency, but as a dynamic mechanism supporting the development of autonomy.

Infant-directed (ID) playsongs and lullabies have distinct acoustic properties connected to their functions to elicit and diffuse infant attention, respectively. In the performative context of ID singing, it is crucial that infants and caregivers adjust to each other for the songs’ function to be reached. In this study, we observed face-to-face ID singing between mothers and their 7-month-old infants and measured variability in maternal singing (i.e., spectral flux) around the onset of infant social gaze toward the mother. Results showed that maternal acoustic variability and infant attention were increased in playsongs over lullabies. Furthermore, mothers increased their acoustic variability both before and after the onset of infant social gaze, especially in playsongs. These findings suggest that mothers increase acoustic variability both to modulate and respond to infant attention, and infants respond to more variable singing by paying more attention to the singing caregiver. Thus, we propose that ID singing interactions are reciprocal, linking infant attentional displays and maternal acoustic responses.

Distinguishing between self and other is fundamental for social interaction through touch and central to bodily self-awareness. Self-touch is known to feel different from being touched by others—typically perceived as less intense—but the underlying mechanisms behind this self-other difference remain a contemporary topic with crucial implications for robotics, virtual realities, and human-machine-interactions. Previous research has largely focused on the body part being touched, overlooking the role of the touching body part, which is equally vital in shaping the tactile experience. Here, we aimed to disentangle the two components of self-touch – touching and being touched – and compared them to other forms of active and passive touch. Across two experiments we examined subjective experience, neural activation, and physiological response using self-report and functional near-infrared spectroscopy. We show that the reduced intensity of self-touch is primarily driven by the touched area, while the touching hand mirrors responses seen in other active touch conditions. Receiving touch was rated as most pleasant, while self-touch was less pleasant than concurrent giving and receiving touch. At the neural level, we introduce novel k-shape clustering for functional near infrared spectroscopy. We found increased bilateral activity in temporal areas during self-touch in comparison to touching while being touched as well as when only receiving touch. Additionally, heartrate and heartrate variability differed between conditions. In conclusion, distinct behavioral and neural responses during self-touch demonstrate that self-touch is not simply a combination of simultaneous touching and being touched sensations and processing. Instead, it constitutes a unique sensory and neural phenomenon—highlighting its critical role in bodily self-representation and offering new insights into the multisensory foundations of self-other distinction.

Interpersonal neural synchrony (INS), the temporal alignment of brain activitiesbetween individuals, has been proposed as a biomarker for successful communication and smooth social interaction. Surging empirical evidence shows that INS emerges spontaneously between infants, children, and their caregivers from early on in development. Yet, little is known about the developmental preconditions and functions of INS in childhood. This paper presents a developmental framework for understanding INS, integrating insights from structural and functional brain maturation, as well as behavioral, social, and cognitive development. We discuss how early caregiver-infant interactions, characterized by shared perceptual rhythms, facilitate the emergence of INS. Given initial limitations in temporal precision of neural processing, early INS is likely constrained to low-frequency brain rhythms and evolves alongside the maturation of neural networks and socio-cognitive abilities. We outline how INS may support critical developmental processes, including social learning, language acquisition, and attachment formation, through enabling mutual prediction and co-regulation between caregivers and children. Furthermore, we hypothesize that tasks requiring higher-order mutual understanding are linked to qualitative changes in INS patterns over time. This framework highlights the potential of INS as both a marker and a driver of developmental change, offering new avenues for research and intervention. Longitudinal studies and rhythm-based interventions could deepen our understanding of how INS supports development, with implications for enhancing social learning and attachment in populations at risk for developmental challenges. This work underscores the importance of adopting a developmental perspective in INS research.

Background: Supported infant-directed singing (IDS) for parents and their preterm infants has proven beneficial for parents and preterm infants’ health and relationship building. Studying parent–infant contingent interactions through behavioral observations is an established method for assessing the quality of interactions. Very few studies have measured contingency between parent and preterm infants in the neonatal period during supported IDS. Methods: We conducted a feasibility study to assess the possibility of analyzing parent–very preterm infant dyads’ contingency during supported IDS in the NICU. We recruited four mother–infant dyads and video-recorded a single music therapy (MT) session before their discharge from the hospital. Two independent researchers coded three selected segments (beginning, middle, and end) from each video, according to adapted behavioral scales with inter-rater agreement analysis. Contingency between infant and maternal behaviors was analyzed. Results: Twelve video segments were coded. High inter-rater agreements (Cohen’s kappa) were found for infant eye-opening (0.93), hand positions (0.79), and head orientation (0.94), as well as maternal head orientation (0.95) and vocalizations (0.95). During supported IDS, increased infant head orientation toward the mother, eyes closed, as well as maternal head orientation toward the infant (all p < 0.001), were recorded compared to no IDS. Direction of the maternal head toward her infant was contingent on the infant’s closed eyes, extended hands, and head not toward mother. Conclusions: This feasibility study demonstrates contingency between mothers and their preterm infants’ specific behaviors during IDS. These interactions can be analyzed through video segments with high inter-rater agreement. The method described might help in evaluating other modalities that might be related to contingency. Recent advances in AI can make this tool easier to accomplish, with further studies to evaluate the importance of contingency for child development. The findings suggest that supported IDS influences infant attention and regulation.

Playful activities provide critical opportunities for rhythmic interactions, which may affect social and cognitive development in early childhood. Prior research suggests that motor synchrony promotes closeness and prosocial behaviour, but few studies have examined its role in social learning and in group settings. This study investigated whether motor synchrony in a clapping game, enhances preschoolers' closeness with others, imitation, over-imitation, and sharing behaviour. In a group setting, motor synchrony and asynchrony were experimentally induced between the child and two experimenters. We hypothesized that children would feel closer, imitate more, and share more with an adult partner who moved in synchrony compared to one who moved asynchronously. Bayesian analyses revealed no credible evidence that the children affiliated, imitated, over-imitated, or shared differently with their synchronous versus asynchronous partner (BF10=0.045-0.216). Manipulation checks indicated that although the adults adhered to the stimuli, there was overall low motor synchrony. These findings highlight the challenges of inducing motor synchrony in playful group settings and raise questions about the level of synchrony necessary to impact social affiliation and learning in young children.