Synchrony in mother-infant vocal interactions revealed through timed event sequences

This report extends a previous cross-cultural study of synchrony in mother-infant vocal interactions (Bornstein et al., 2015) to immigrant samples. Immigrant dyads from three cultures of origin (Japan, South Korea, South America) living in the same culture of destination (the United States) were compared to nonmigrant dyads in those same cultures of origin and to nonmigrant European American dyads living in the same culture of destination (the United States). This article highlights an underutilized analysis to assess synchrony in mother-infant interaction and extends cross-cultural research on mother-infant vocal interaction. Timing of onsets and offsets of maternal speech to infants and infant nondistress vocalizations were coded separately from 50-min recorded naturalistic observations of mothers and infants. Odds ratios were computed to analyze synchrony in mother-infant vocal interactions. Synchrony was analyzed in three ways -- contingency of timed event sequences, mean differences in contingency by acculturation level and within dyads, and coordination of responsiveness within dyads. Immigrant mothers were contingently responsive to their infants’ vocalizations, but only Korean immigrant infants were contingently responsive to their mothers’ vocalizations. For the Japanese and South American comparisons, immigrant mothers were more contingently responsive than their infants (but not robustly so for South American immigrants). For the Korean comparison, mean differences in contingent responsiveness were found among acculturation groups (culture of origin, immigrant, culture of destination), but not between mothers and infants. Immigrant dyads’ mean levels of responsiveness did not differ. Immigrant mothers’ and infants’ levels of responsiveness were coordinated. Strengths and flexibility of the timed event sequential analytic approach to assessing synchrony in mother-infant interactions are discussed, particularly for culturally diverse samples.     

Young Children’s Physiological Reactivity during Memory Recall: Associations with Posttraumatic Stress and Parent Physiological Synchrony

Autonomic reactivity is implicated in stress response and social engagement – both key components of posttraumatic stress disorder (PTSD) – but few studies have examined autonomic reactivity in pediatric samples, and no known studies have examined physiological synchrony among children with PTSD and caregivers. In a sample of 247 young children (94 girls, 153 boys), most (85%) of whom had exposure to trauma and 40% who met criteria for PTSD, we examined children’s patterns of respiratory sinus arrhythmia (RSA) at baseline and in response to a memory recall task, as well as correspondence between parents’ and children’s RSA. Children with PTSD demonstrated significantly higher reactivity than other groups during their recollection of a traumatic memory, but not during other memory tasks. Regarding synchrony, caregivers’ and children’s RSA were more significantly and positively correlated during the trauma recall task among children who had had exposure to a potentially traumatic event but did not meet PTSD criteria, suggesting physiological synchrony may be protective in contexts of trauma. Overall, findings demonstrate physiological reactivity differences among young children with PTSD. While more work is needed to understand the meaning of parent-child physiological synchrony, these data suggest that children’s psychopathology is associated with physiological synchrony processes among young children with exposure to trauma.     

Gender differences in synchrony: Females in sync during unstructured dyadic conversation

Although previous studies have reported that individual prosocial traits generally enhance synchrony, gender as a social factor was not the subject of focus. The present study examined gender differences in synchrony by conducting three experiments on dyadic unstructured conversations with same-gender strangers. Synchrony was assessed by calculating the cross-wavelet coherence and determining the relative phase. As expected, through the three experiments, the female dyads showed a higher degree of synchrony, compared to the male dyads. Moreover, the conversation type (i.e., structured monologue vs. unstructured dialogue) did not moderate the gender effect (Experiment 2), while synchrony in the female dyads was influenced by the preceding conversation (Experiment 3). In contrast, through the three experiments, the role of the relative phase was unclear. The findings indicate that the social factor, gender, has an impact on synchrony, and that interpersonal sensitivity contributes to synchrony.     

Dyadic synchrony among young Latina mothers and their toddlers: The role of maternal and child behavior

Synchronous interactions are an important indicator of parent-child relationship quality with positive implications for child development. Latina adolescent mothers face several demographic challenges that place them at risk for less synchronous interactions. To identify factors that may facilitate more optimal parent-child relationships in this population, our study examined maternal sensitivity and children’s behavioral styles as joint predictors of dyadic synchrony among young Latina mothers and their toddlers. Mother-toddler dyads (N = 170) were observed interacting across different tasks, and toddlers’ behavior was observed during the administration of a developmental test. Results of multivariate regressions revealed additive effects of maternal sensitivity and child behavioral styles (i.e., dysregulation and positive attentional control). Maternal sensitivity related to higher dyadic synchrony for the entire sample. Positive attentional control was related to higher dyadic synchrony for mother-daughter dyads only. Although no gender differences in dyadic synchrony or the behavior style variables emerged, the relative contribution of maternal and child factors differed by child gender, suggesting that mothers may have responded differently to similar behavior and affect displayed by boys and girls. The findings provide insights regarding factors that contribute to dyadic synchrony in this understudied population and emphasize the need to consider child gender when studying parent-child interactions in young Latina families.     

Maternal and infant touching behaviours during perturbed interactions: Associations with maternal depressive symptomatology and infant crying

Touch is an important means through which mothers and infants co-regulate during periods of stress or perturbation. The present study examined the synchrony of maternal and infant touching behaviours among 41 mother-infant dyads, some of whom were deemed at-risk due to maternal depressive symptomatology. Mothers and their 4-month-old infants participated in the Still-Face (maternal emotional unavailability; SF) and Separation (maternal physical unavailability; SP) procedures. Infant crying was examined across procedures and investigated as a brief period of perturbation. Results revealed that mothers and infants displayed a positive pattern of tactile synchrony (coordinated, analogous changes in touch) during infant crying episodes. However, dyads in the high depression group displayed significantly less affectionate touch during instances of infant crying. Furthermore, more depressive symptoms were associated with less maternal and infant touch and lower rates of infant crying. This group of dyads may be less expressive via touch, be less affected by disruptions in their interactions, have impaired regulatory abilities, or simply require minimal amounts of touch to mutually regulate following social stressors and during brief perturbation periods. These findings enrich our limited knowledge about the dynamic interplay of maternal and infant touch and inform preventative intervention programs for at-risk groups.     

Quantitative evaluation of infant behaviour and mother–infant interaction: An overview of a japanese interdisciplinary programme of research

This paper provides an overview of an interdisciplinary programme of research started more than 20 years ago at the University of Tokyo. A major aim of this programme was (and still is) to develop methods and related forms of quantitative analysis that provide rigorous evaluations of infant behaviour from a particular theoretical perspective. In one part of the programme telethermography is used to measure emotional changes in young infants. Contrary to the accepted view in attachment theory, infants as young as 2–3 months showed evidence of stress following separation from the mother (as indexed by a drop in the skin temperature of the infant's forehead). In another part, we established the presence of interpersonal synchrony between arm movements of the newborn and the speech of the mother and other adults, using computer assisted pattern recognition techniques. On the basis of this finding, we have proposed a simulation model of mother-infant interaction from the perspective of system information theory. In general, our programme of research provides a theoretically driven set of techniques and analytical approaches that may provide deeper insights into early development and parenting.     

The association between maternal smoking and secondhand exposure and autonomic functioning at 2-4 weeks of age

This study examined the association between maternal smoking and exposure to environmental tobacco smoke (ETS) during pregnancy and infant heart rate. Participants were 62 mother-infant dyads where mother smoked during pregnancy, 47 dyads where mother did not smoke during pregnancy but was exposed to ETS and 47 dyads where mother did not smoke and was not exposed to ETS. Average heart rate (HR) and respiratory sinus arrhythmia (RSA) were assessed at 2-4 weeks of age during sleep. Infants in both exposure groups had higher HR and lower RSA than nonexposed infants. Furthermore, boys in both exposure groups had higher HR and lower RSA than girls. These results highlight the importance of considering prenatal ETS exposure and infant gender when assessing infant outcomes.     

Chronic stress in the mother-infant dyad: Maternal hair cortisol,infant salivary cortisol and interactional synchrony

Stress physiology is shaped by early experience, with enduring effects on health. The relation of chronic maternal physiological stress, as indexed by hair cortisol, to infants’ stress systems and to mother-infant interaction quality has not been established. We examined maternal hair and salivary cortisol, six-month-old infants’ salivary cortisol, and mother-infant interaction in 121 mother-infant dyads. High maternal hair cortisol was related to higher infant average salivary cortisol concentration. Maternal hair cortisol and bedtime salivary cortisol were both uniquely related to infant bedtime salivary cortisol. Mothers with higher hair cortisol were more intrusive and had lower positive engagement synchrony with their infants. Maternal intrusiveness moderated the association of maternal hair cortisol and infant salivary cortisol, such that maternal hair and infant average salivary cortisol were related only when mothers were more intrusive. Maternal chronic physiological stress may upregulate infants’ developing stress systems, particularly in the context of lower mother-infant interaction quality.     

The effects of SES on infant and maternal diurnal salivary cortisol output

The present study directly compared diurnal salivary cortisol output and maternal-infant synchrony in low and high socio-economic status (SES) mother–infant dyads. Saliva cortisol samples were collected from 32 6–12-month-old infants and their mothers on the same day in the morning, afternoon and evening, and assayed for free cortisol concentration. Low-SES infants and mothers exhibited higher average salivary cortisol output, without dysregulation, compared to high-SES infants. Low-SES infants and mothers also showed reduced synchrony in cortisol output compared to high-SES infants and mothers. Results are discussed with respect to maternal sensitivity and early stress reduction interventions.     

When I move,you move: Associations between automatic and person-coded measures of infant-mother synchrony during free-play using virtual in-home data collection

The relationship between movement synchrony and global scores of behavioral synchrony were investigated during a naturalistic free-play between 33 infants (ages 12- to 24-months) and their mothers using a video-conferencing platform. We assessed movement synchrony by applying an automatic tool, motion-energy analysis (MEA), to the obtained video data. Dyadic movement synchrony was associated with higher levels of maternal sensitivity, infant involvement, dyadic reciprocity, and a child-led interaction pattern. This demonstrates the feasibility of using MEA as an automatic tool for assessing movement synchrony in mother-infant dyads and its application for investigating naturalistic at-home free play sessions in a remote setting.     

On Measuring and Modeling Physiological Synchrony in Dyads

Physiological synchrony within a dyad, or the degree of temporal correspondence between two individuals' physiological systems, has become a focal area of psychological research. Multiple methods have been used for measuring and modeling physiological synchrony. Each method extracts and analyzes different types of physiological synchrony, where ‘type’ refers to a specific manner through which two different physiological signals may correlate. Yet, to our knowledge, there is no documentation of the different methods, how each method corresponds to a specific type of synchrony, and the statistical assumptions embedded within each method. Hence, this article outlines several approaches for measuring and modeling physiological synchrony, connects each type of synchrony to a specific method, and identifies the assumptions that need to be satisfied for each method to appropriately extract each type of synchrony. Furthermore, this article demonstrates how to test for between-dyad differences of synchrony via inclusion of dyad-level (i.e., time-invariant) covariates. Finally, we complement each method with an empirical demonstration, as well as online supplemental material that contains Mplus code.     

Synchrony,complexity and directiveness in mothers’ interactions with infants pre- and post-cochlear implantation

This study investigated effects of profound hearing loss on mother–infant interactions before and after cochlear implantation with a focus on maternal synchrony, complexity, and directiveness. Participants included two groups of mother–infant dyads: 9 dyads of mothers and infants with normal hearing; and 9 dyads of hearing mothers and infants with profound hearing loss. Dyads were observed at two time points: Time 1, scheduled to occur before cochlear implantation for infants with profound hearing loss (mean age = 13.6 months); and Time 2 (mean age = 23.3 months), scheduled to occur approximately six months after cochlear implantation. Hearing infants were age-matched to infants with hearing loss at both time points. Dependent variables included the proportion of maternal utterances that overlapped infant vocalizations, maternal mean length of utterance, infant word use, and combined maternal directives and prohibitions. Results showed mothers’ utterances overlapped the vocalizations of infants with hearing loss more often before cochlear implantation than after, mothers used less complex utterances with infants with cochlear implants compared to hearing peers (Time 2), and mothers of infants with profound hearing loss used frequent directives and prohibitions both before and after cochlear implantation. Together, mothers and infants adapted relatively quickly to infants’ access to cochlear implants, showing improved interactional synchrony, increased infant word use, and levels of maternal language complexity compatible with infants’ word use, all within seven months of cochlear implant activation.     

Dyadic drumming across the lifespan reveals a zone of proximal development in children

Many social interactions require the synchronization--be it automatically or intentionally--of one's own behavior with that of others. Using a dyadic drumming paradigm, the authors delineate lifespan differences in interpersonal action synchronization (IAS). Younger children, older children, younger adults, and older adults in same- and mixed-age dyads were instructed to drum in synchrony with their interaction partner at a constant, self-chosen tempo. Adult-only dyads showed the highest and children-only the lowest levels of IAS accuracy. It is important to note that children improved reliably in IAS accuracy when paired with older partners. The observed age-related differences in IAS accuracy remained reliable after statistically controlling for individual differences in the ability to synchronize to a metronome and for between-dyad differences in tempo. The authors conclude that IAS improves from middle childhood to adulthood and that adult interaction partners may facilitate its development.     

Dynamics of frontal alpha asymmetry in mother-infant dyads: Insights from the Still Face Paradigm

The parent-infant dynamic has a foundational role in emotion regulation development. Electroencephalography (EEG) hyperscanning from mother-infant dyads can provide an unprecedented window into inter-brain dynamics during the parent-infant exchange. This potential depends on the feasibility of hyperscanning with dyads in emotionally taxing contexts. We sought to demonstrate feasibility of hyperscanning from 10 mother-infant dyads during the Still Face Procedure (SFP). We measured frontal alpha asymmetry (FAA) to elucidate ongoing regulatory dynamics and considered maternal caregiving quality as a window into dyads’ history. Results showed dyads exhibited a rightward shift in FAA over the course of SFP, indicating growing negative emotionality and desire to withdraw. Results also showed growing variability in FAA for infants over the course of SFP, indicating less active emotional control as stress ensued. Variability was especially low for mothers during periods when asked to be emotionally unavailable, suggesting active control to match the task demands. Dyads with a more responsive mother exhibited higher (more left) FAA relative to dyads with a less responsive mother, which might reflect a more positive emotional experience overall. We raise important methodological and theoretical questions that hyperscanning during SFP can address, such as the developmental origins of trait-like self-regulatory dispositions.     

Responding to distressed infants: Does mothers’ positive versus negative affect matter for infants' behavior and physiology?

How mothers respond to infants’ distress has implications for infants’ development of self-regulation and social competence. In a sample of 35 mothers and their 4- to 8-month-old infants, we induced infant distress using an arm restraint task and compared infants’ observed affect and physiological responses under two conditions, when mothers were instructed to respond with: 1) positive affect and 2) negative affect. Based on theoretical and empirical support, we empirically evaluated two opposing hypotheses. Based on the Mutual Regulation Model and work on affect matching, we predicted that when mothers respond with negative affect versus positive affect, distressed infants’ duration of negative affect would be smaller, negative affect would be less intense, and respiratory sinus arrythmia (RSA) withdrawal would be lower. Based on social referencing theory and research, we expected that when mothers respond with positive affect versus negative affect, distressed infants’ duration of negative affect would be smaller, negative affect would be less intense, and RSA withdrawal would be lower. We found that when mothers responded to their distressed infants with negative affect versus positive affect, infants spent significantly more time in negative affect, their intensity of expressed negative affect was greater, and their RSA withdrawal was greater, suggesting that mothers’ display of mild positive affect when infants are distressed may be helpful for infants. The current findings add to accumulating evidence that mothers’ positive relative to negative affective response to their infants’ distress can produce observable differences in infants’ duration and intensity of negative affect, as well as their physiology. Findings have the potential to inform future research that investigates how mothers can most effectively reduce their infants’ distress and intervention that targets the moment-to-moment behaviors in mother-infant reciprocal interactions.     

Effects of tonic and phasic respiratory sinus arrhythmia on affective stress responses

Adaptive affective responses in the face of environmental challenges require flexible physiological responding. The present study examined the extent to which tonic respiratory sinus arrhythmia (RSA)-a putative marker of regulatory capacity-moderated the association between stress-related changes in RSA (i.e., phasic RSA) and concurrent changes in affect. Ninety-eight healthy, young adults completed ratings of affect during a resting baseline and following the recall of a recent stressor. Tonic RSA moderated the association of phasic RSA with stress-related change in positive affect (PA), such that change in RSA had a positive association with PA for individuals with higher tonic RSA and a negative association for those with lower tonic RSA. Examination of specific aspects of PA indicated that phasic RSA was positively associated with changes in ratings of attentive engagement among individuals with higher tonic RSA. These findings inform our understanding of phasic RSA and support the notion that flexible parasympathetic nervous system functioning is an important component of adaptive stress regulation.     

The coregulatory effects of emotionally focused therapy

This study examined the heart rate synchrony between a single couple in emotionally focused therapy (EFT) as a method of measuring coregulatory effects over the course of treatment. A clinician who is an EFT certified therapist, supervisor, and trainer administered all eight sessions in a private practice setting. Surrogate synchrony analysis assessed heart rate synchrony between partners, indicating that significant heart rate synchrony was more likely over time. Significant heart rate synchrony was more likely during sessions that focused on clients’ sharing attachment injuries, bonds, and longings with their partner compared to sessions more focused on cognitive processing of the relationship. Additionally, there were delays in heart rate synchrony that occurred between the couple, which may be indicative of the emotional processing speed of the empathic response of each partner. Understanding the physiological synchrony patterns between dyads in treatment could clarify the potential of coregulation in the therapeutic process.     

Measures of infant behavioral and physiological state regulation predict 54‐month behavior problems

This study investigated whether measures of infant temperament, regulatory disorders, and physiological reactivity and concurrent measures of family environment were predictors of child behavior problems at 54 months of age. The sample consisted of 23 children–mother dyads. The sample recruitment strategy emphasized testing both typical and fussy/difficult infants at 9 months of age. Children were categorized into low and high behavioral problem groups at 54 months of age. The children in the high behavioral problem group were more likely at 9 months to have been temperamentally difficult, to have been classified as regulatory disordered, and to have displayed respiratory sinus arrhythmia (RSA) regulation difficulties. These children also were more likely to come from families described as less cohesive and providing less focus on active/recreational activities when the children were 54 months old. A logistic regression analysis, including only the 9‐month infant measures (i.e., difficultness, regulatory disorders classification, and RSA regulation), resulted in a significant model with 100.0% accurate classification into high or low behavioral problem groups. Data suggest that infant measures of behavioral and physiological state regulation may be early indicators of child behavior problems, especially internalizing problems.     

Mother–infant mutual eye gaze supports emotion regulation in infancy during the Still-Face paradigm

This study was designed to examine the sequential relationship between mother–infant synchrony and infant affect using multilevel modeling during the Still Face paradigm. We also examined self-regulatory behaviors that infants use during the Still-Face paradigm to modulate their affect, particularly during stressors where their mothers are not available to help them co-regulate. There were 84 mother–infant dyads, of healthy full term 4 month old infants. Second-by-second coding of infant self-regulation and infant affect was done, in addition to mother–infant mutual eye gaze. Using multilevel modeling, we found that infant affect became more positive when mutual gaze had occurred the previous second, suggesting that the experience of synchronicity was associated with observable shifts in affect. We also found a positive association between self-regulatory behaviors and increases in positive affect only during the Still-Face episode (episode 2). Our study provides support for the role of mother–infant synchronicity in emotion regulation as well as support for the role of self-regulatory behaviors in emotion regulation that can have important implication for intervention.     

Touch attenuates infants’ physiological reactivity to stress

Animal studies demonstrate that maternal touch and contact regulate infant stress, and handling during periods of maternal deprivation attenuates the stress response. To measure the effects of touch on infant stress reactivity during simulated maternal deprivation, 53 dyads were tested in two paradigms: still‐face (SF) and still‐face with maternal touch (SF+T). Maternal and infant cortisol levels were sampled at baseline, reactivity, and recovery and mother’s and infant’s cardiac vagal tone were measured during the free play, still‐face, and reunion episodes of the procedure. Cortisol reactivity was higher among infants in the SF condition and while cortisol decreased at recovery for infants in the SF+T, it further increased for those in the SF. Vagal tone showed a greater suppression when SF was not accompanied by maternal touch. Touch synchrony during free play was associated with higher infant vagal tone, whereas touch myssynchrony – maternal tactile stimulation while the infant gaze averts – correlated with higher maternal and infant cortisol. In humans, as in mammals, the provision of touch during moments of maternal unavailability reduces infants’ physiological reactivity to stress.