Mother-infant interaction and infant development in women at risk of postpartum psychosis with and without a postpartum relapse.

BACKGROUND: This study aimed to investigate mother-infant interaction and infant development in women at-risk of postpartum psychosis (PP), with and without a postpartum relapse. METHODS: 103 women (and their offspring) were included, 43 at-risk-of-PP because of a diagnosis of bipolar disorder, schizoaffective disorder or previous PP, and 60 with no current/previous mental illness or family history of PP. Of the at-risk women, 18 developed a psychiatric relapse within 4 weeks after delivery (AR-unwell), while 25 remained symptom-free (AR-well). Mother-infant interaction was assessed using the CARE-Index at 8 weeks' and 12 months' postpartum and infant development using the Bayley-III at 12 months' postpartum. RESULTS: Women at-risk-of-PP as a group, regardless of whether they developed a psychiatric relapse within 4 weeks after delivery, had less synchronous mother-infant interactions and had infants with less optimal cognitive, language, motor and socio-emotional development than healthy controls. In particular, boys of at-risk women had the lowest scores in cognitive, language and motor development and in mother-infant interaction, while girls of the at-risk women had the lowest scores in socio-emotional development. The synchrony in the dyad predicted infant cognitive and language development. There was no evidence for a difference in mother-infant interaction nor in infant development between the AR-unwell and AR-well groups. CONCLUSIONS: These results suggest that, while there is a lack of evidence that an early postpartum relapse in women at-risk-of-PP could represent a risk for the infant per se, maternal risk for PP may be associated with less optimal mother-infant interaction and infant development.

Parent-child interaction at age 5 months: genetic and environmental contributions and associations with later socio-communicative development.

BACKGROUND: Characteristics of parent-child interaction (PCI) early in life have been associated with later development in the child. Twin studies can help to disentangle child contributions to parent-child interaction, for example, by assessing the influence of the child's genetics on his/her social environment, which includes parental behaviour. METHODS: Infant twins from a community sample [354 monozygotic (MZ), 268 same-sex dizygotic (DZ)] were assessed in terms of PCI at age 5 months. We used the classical twin design to map the aetiology of several parent and child PCI scales and their covariation. We investigated the relations between PCI and later parent-rated child's social communication, language, and autistic traits at ages 2 and 3. RESULTS: Heritability was below 20% for all the included PCI traits. Unique (nonshared) environmental influences substantially overlapped across several PCI scales, suggesting that idiosyncrasies linked to each session shaped the scoring of several traits in a systematic way. Factor analysis revealed three uncorrelated latent factors, which were conceptualized as 'child negative affect', 'positive affective interaction', and 'parent's supportive strategies'. Parents who were rated highly on 'sensitive responsiveness' at 5 months tended to rate their offspring higher in terms of socio-communicative and language development and lower in terms of autistic traits in the second and third years of life. CONCLUSIONS: This study maps the phenotypic and aetiological structure of PCI in early infancy and supports the view that parents' sensitive responsiveness towards their infant is associated with later developmental gains in several domains. We did not find strong evidence of any so-called evocative genetic effects on parents' behaviour. We discuss the results considering the general challenge for lab-based observational PCI measures to capture the richness of parent-child interaction.

Association of SARS-CoV-2 infection during late pregnancy with maternal and neonatal outcomes.

BACKGROUND: Limited data on the impact of the coronavirus disease 2019 (COVID-19) during pregnancy on newborn outcomes are available. This study aimed to characterize and compare the clinical outcomes of newborns from women with and without the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection during late pregnancy. METHOD: This was a retrospective cohort study of women who were either infected or not infected with the SARS-CoV-2 virus during late pregnancy. The neonatal complications associated with COVID-19-positive pregnant women were investigated and analyzed. RESULTS: Among 2063 pregnant women over 28 weeks of gestation, 1.2%, 3.3%, and 18.7% of patients with multiple pregnancies, abnormal fetal positions, and lack of maternal or neonatal follow-up data, respectively, were excluded. Patients who were COVID-19-negative (60.6%) and -positive (16.2%) remained for further analysis. SARS-CoV-2 infection was significantly associated with higher SARS-CoV-2 infection rates in newborns (0% vs. 1.49%, P < 0.01) and longer duration of hospital stay (6.39 ± 2.2 vs. 4.92 ± 1.6, P < 0.01). However, comparing neonatal complications, including Apgar score, preterm birth, low birth weight, cesarean section rate, newborn hearing, neonatal congenital heart defects, and height and weight compliance rate of 6-month-old children, between non-infected and infected participants did not reach statistical significance. CONCLUSION: SARS-CoV-2 infection in late pregnancy has no significant impact on neonatal outcomes. After six months of follow-up of the neonates, we observed that SARS-CoV-2 infection in the third trimester of pregnancy did not affect their growth and development. Hopefully, these findings will guide management strategies and clinical practice.

High-risk pregnancy and its relationship with the neurodevelopment and behavior of 2-year-old children.

High-risk pregnancies elevate maternal stress, impacting offspring neurodevelopment and behavior. This study, involving 112 participants, aimed to compare perceived stress, neurodevelopment, and behavior in high-risk and low-risk pregnancies. Two groups, high-risk and low-risk, were assessed during pregnancy for stress using hair cortisol and psychological analysis. At 24 months post-birth, their children's neurodevelopment and behavior were evaluated. Results revealed higher perceived stress and pregnancy-related concerns in high-risk pregnancies, contrasting with low-risk pregnancies. Offspring from high-risk pregnancies displayed elevated internalizing behavior scores, while low-risk pregnancies showed higher externalizing behavior scores. Additionally, women in low-risk pregnancies exhibited increased cortisol concentrations 24 months post-delivery. These findings underscore the necessity for early stress detection and prevention programs during pregnancy, particularly in high-risk cases, to enhance maternal and infant health.

Diagnostic accuracy of Ages and Stages Questionnaire, Third Edition to identify abnormal or delayed gross motor development in high-risk infants.

AIM: To investigate the diagnostic accuracy of parent-completed Ages and Stages Questionnaire, Third Edition (ASQ-3) to identify abnormal or delayed gross motor development in infants born less than 1000 g or less than 28 weeks gestation. METHODS: Prospective cohort study of high-risk infants comparing ASQ-3 as the index test with concurrent score on Alberta Infant Motor Scale (AIMS) as the reference standard, at 4-, 8- and 12-month corrected (post-term) age. Reference standard positivity cut-offs were 'Abnormal motor development' (AIMS Clinical Range) and 'Motor delay' (AIMS score >1 SD below mean, not captured in Clinical Range). RESULTS: Participating infants (n = 191) had mean gestational age (95% confidence interval (CI)) 26.8 weeks (26.6-27.1) and mean birthweight (95% CI) 870 g (844-896). AIMS rated 51%, 31% and 23% of infants as having 'Abnormal motor development' and 12%, 28% and 13% with 'Motor delay', at 4, 8 and 12 months, respectively. Diagnostic accuracy of ASQ-3 to identify abnormal motor development was acceptable for older infants only if 'Monitor' cut-off was used: sensitivity (95% CI) 33% (23-44), 86% (73-95) and 80% (63-92) and specificity (95% CI) 84% (74-92), 76% (66-84), and 76% (67-83) at 4, 8 and 12 months, respectively. ASQ-3 sensitivity to identify motor delay was low. CONCLUSIONS: ASQ-3 has poor sensitivity to identify abnormal or delayed motor development at 4 months. Using the 'Monitor' cut-off improves the diagnostic accuracy of ASQ-3 for identification of older infants with abnormal motor development who are at high risk of motor disability. However, ASQ-3 has poor sensitivity to identify motor delay. Clinical motor assessment of high-risk infants is recommended, particularly in early infancy.

Factors Associated with Suspected Developmental Delay in Thai Children Born with Low Birth Weight or Asphyxia.

OBJECTIVES: The aim of the study was to identify factors associated with a risk of suspected developmental delay (SDD) in high-risk children in Thailand. METHODS: We used data on children enrolled for developmental delay (DD) screening across Thailand collected by the Rajanagarindra Institute of Child Development, Department of Mental Health, Ministry of Public Health, Thailand. Children who were under 5 years of age with a birth weight of fewer than 2500 g and/or birth asphyxia in Thailand with high risk of DD were assessed using the Developmental Assessment for Intervention Manual (DAIM) between August 2013 and November 2019 (N = 14,314). RESULTS: The high-risk children who had a gestational age at birth of < 37 weeks (adjusted odds ratio = 1.54; 95% confidence interval = 1.39-1.70) and/or had a birth weight < 2500 g (1.22; 1.02-1.45), or had mothers who were not government officers (1.46; 1.11-1.93), had a low education level (1.36; 1.19-1.55), had a poor nutritional status (1.34; 1.09-1.65), and/or who were living in a high-altitude area (1.59; 1.32-1.91) were at a higher risk of SDD. CONCLUSIONS FOR PRACTICE: Children with a low birth weight and/or asphyxia during birth had a high risk of DD. SDD monitoring of children by community health workers and/or by developing outreach strategies, especially in underserved regions, should be considered. In addition, developing policies and guidelines, and intervention for high-risk children ought to be conducted to reduce the subsequent problems caused by the late detection of DD.

Towards novel classification of infants' movement patterns supported by computerized video analysis.

BACKGROUND: Positional preferences, asymmetry of body position and movements potentially indicate abnormal clinical conditions in infants. However, a lack of standardized nomenclature hinders accurate assessment and documentation of these preferences over time. Video tools offer a safe and reproducible method to analyze and describe infant movement patterns, aiding in physiotherapy management and goal planning. The study aimed to develop an objective classification system for infant movement patterns with particular emphasis on the specific distribution of muscle tension, using methods of computer analysis of video recordings to enhance accuracy and reproducibility in assessments. METHODS: The study involved the recording of videos of 51 infants between 6 and 15 weeks of age, born at term, with an Apgar score of at least 8 points. Based on observations of a recording of infant spontaneous movements in the supine position, experts identified postural-motor patterns: symmetry and typical asymmetry linked to the asymmetrical tonic neck reflex. Deviations from the typical postural-motor system were indicated, and subcategories of atypical patterns were distinguished. A computer-based inference system was developed to automatically classify individual patterns. RESULTS: The following division of motor patterns was used: (1) normal patterns, including (a) typical (symmetrical, asymmetrical: variants 1 and 2); and (b) atypical (variants: 1 to 4), (2) positional preference, and (3) abnormal patterns. The proposed automatic classification method achieved an expert decision mapping accuracy of 84%. For atypical patterns, the high reproducibility of the system's results was confirmed. Lower reproducibility, not exceeding 70%, was achieved with typical patterns. CONCLUSIONS: Based on the observation of infant spontaneous movements, it is possible to identify movement patterns divided into typical and atypical patterns. Computer-based analysis of infant movement patterns makes it possible to objectify and satisfactorily reproduce diagnostic decisions.

Social Support and Spousal Relationship Quality Improves Responsiveness among Anxious Mothers.

Maternal responsiveness, a mother's ability to consistently identify infant cues and then act on them, is critical for healthy child development. A woman's social support and spousal relationship may affect responsiveness to an infant, especially among mothers with anxiety. We assessed how social support and spousal relationship quality is associated with responsiveness among anxious mothers, and if postpartum depression (PPD) moderated these associations. Cross-sectional data were collected from 2019 to 2022 in a public hospital in Pakistan from 701 women at six-weeks postpartum. Eligible women had at least mild anxiety in early- to mid- pregnancy. Linear regression analyses assessed if spousal relationship quality and social support from family and friends were associated with maternal responsiveness, measured using the Maternal Infant Responsiveness Instrument. Interaction terms were used to examine if PPD moderated these associations. Spousal relationship quality (B = 2.49, 95% CI: 1.48, 3.50) and social support (B = 1.07, 95% CI: 0.31, 1.83) were positively related to maternal responsiveness to the infant. Emotional support from a spouse was positively associated with responsiveness (B = 1.08, 95% CI: 0.12, 2.03 depressed; B = 2.96, 95% CI: 1.34, 4.58 non-depressed), and conflict with the spouse was negatively associated with responsiveness (B=-1.02, 95% CI: -1.94, -0.09 depressed; B=-2.87, 95% CI: -4.36, -1.37 non-depressed). However, social support was related to responsiveness only in non-depressed women (B = 2.61, 95% CI: 1.14, 4.07). While spousal relationships and social support enhance maternal responsiveness, for depressed women, spousal relationships were particularly critical. In considering maternal-infant interventions to improve child development outcomes, our study indicates the importance of supportive relationships that foster effective responsiveness.

The interplay between emotional and breastfeeding difficulties in first-time mothers.

AIM/BACKGROUND: Both mental maternal health and breastfeeding difficulties impact maternal and infant health. The present study analyses the association between psychosocial and breastfeeding variables and maternal mental health. DESIGN/METHODS: The participants were 107 first-time mothers from Chile. Sociodemographic variables and breastfeeding difficulties were assessed at 6 weeks postpartum. Depression and anxiety symptoms, parental self-efficacy, and perceived social support were measured using validated, self-report questionnaires at 6 weeks and 5 months postpartum. This study is a secondary analysis of an intervention trial. RESULTS: 76% of the women reported having experienced some breastfeeding difficulty in the first postpartum weeks. The number of breastfeeding difficulties was associated with maternal mental health symptoms at 6 weeks postpartum and parental self-efficacy at both assessment times. Women who did not experience breastfeeding difficulties presented significantly fewer depressive (t(102) = 2.5, p = .015) and anxiety symptoms (t(50) = 2.3, p = .028) at 6 weeks postpartum than those who did. Mothers who exclusively breastfed at 5 months postpartum presented significantly higher parental self-efficacy (t(94) = 2.4, p = .044). A higher number of breastfeeding difficulties and low perceived social support contributed to higher depressive symptoms (R2 = .30; F(3,103) = 14.6, p < .001), anxiety symptoms (R2 = .32, F(3.103) = 17.27, p < .001) and lower parental self-efficacy at 6 weeks postpartum (R2 = .39; F(2,103) = 9.4, p < .001). CONCLUSION: Breastfeeding difficulties and social support are associated with fewer mental health symptoms and higher parental self-efficacy during early postpartum in first-time mothers.

Depth and Quality of Recommendations in Popular Sources About How to Play with Infants: Content Analysis.

AIM: Systematically evaluate the depth and quality of play recommendations provided in popular sources for parents of infants in the first year of life. METHODS: This represents the second stage of a larger analysis of educational content available to parents. Two coders (>90% agreement) extracted and coded play activities from popular websites, applications, and books screened from a systematic online search. Depth of instruction variables were extracted. Activity quality was rated based on opportunities for child-initiated movement, problem-solving with objects, and responsive communication. RESULTS: 4370 play activities from 214 sources were analyzed. Activities were likely to suggest specific ages for infants and that a caregiver be present. Less than half of the activities incorporated toys or provided guidance about how to position or physically support infants. Activity quality was low; most activities did not explicitly encourage parents to provide opportunities for child-initiated movement, problem-solving with objects, or quality communication. CONCLUSIONS: Parents may encounter a large number of play activities in popular sources, but the depth of instruction and quality of those activities could be improved. Provision of higher-quality education to parents may enhance parent-child play interactions to positively impact parent and child outcomes, especially for children at risk for delays.

A Feasibility Study of a Physical and Occupational Therapy-Led and Parent-Administered Program to Improve Parent Mental Health and Infant Development.

AIMS: Extremely premature birth puts infants at high risk for developmental delay and results in parent anxiety and depression. The primary objective of this study was to characterize feasibility and acceptability of a therapist-led, parent-administered therapy and massage program designed to support parent mental health and infant development. METHODS: A single cohort of 25 dyads - parents (24 mothers, 1 father) and extremely preterm (<28 wk gestation) infants - participated in the intervention. During hospitalization, parents attended weekly hands-on education sessions with a primary therapist. Parents received bi-weekly developmental support emails for 12 months post-discharge and were scheduled for 2 outpatient follow up visits. We collected measures of parent anxiety, depression, and competence at baseline, hospital discharge, and <4 and 12 months post-discharge. RESULTS: All feasibility targets were met or exceeded at baseline and discharge (≥70%). Dyads participated in an average of 11 therapy sessions (range, 5-20) during hospitalization. Lower rates of data collection adherence were observed over successive follow ups (range, 40-76%). Parent-rated feasibility and acceptability scores were high at all time points. CONCLUSIONS: Results support parent-rated feasibility and acceptability of the TEMPO intervention for extremely preterm infants and their parents in the Neonatal Intensive Care Unit.

The Role of Social Support in Perinatal Mental Health and Psychosocial Stimulation.

Social support refers to the help someone receives emotionally or instrumentally from their social network. Poor social support in the perinatal period has been associated with increased risk for symptoms of common mental disorders, including depression and posttraumatic stress symptoms (PTS), which may impact parenting behavior. Whether social support impacts parenting behaviors, independent of mental health symptomatology, remains unclear. Among N=309 participants of the Scaling Up Maternal Mental healthcare by Increasing access to Treatment (SUMMIT Trial), a large perinatal depression and anxiety treatment trial, we explored the relations between perceived social support, perinatal depressive and PTS symptoms, and psychosocial stimulation provided by the parent in their home environment. Social support was measured at baseline using the Multidimensional Scale of Perceived Social Support (MSPSS). Perinatal depressive symptoms were measured by the Edinburgh Postnatal Depression Scale (EPDS) and PTS symptoms were measured by the Abbreviated PTSD Checklist (PCL-6) at baseline, 3-, and 6-months post-randomization. Psychosocial stimulation was assessed by the Home Observation Measurement of the Environment (HOME) when the infant was between 6 to 24 months. Using stepwise hierarchical regressions, we found: (1) perceived social support at baseline significantly predicted both depressive and PTS symptoms at 3-months post-randomization, even when controlling for baseline depressive and PTS symptoms; and (2) while neither depressive nor PTS symptoms were significantly associated with psychosocial stimulation, perceived social support at baseline was a significant predictor. Clinical implications regarding treatment of perinatal patients are discussed.

Open Science Considerations for Descriptive Research in Developmental Science.

Descriptive developmental research seeks to document, describe, and analyze the conditions under which infants and children live and learn. Here, we articulate how open-science practices can be incorporated into descriptive research to increase its transparency, reliability, and replicability. To date, most open-science practices have been oriented toward experimental rather than descriptive studies, and it can be confusing to figure out how to translate open-science practices (e.g., preregistration) for research that is more descriptive in nature. We discuss a number of unique considerations for descriptive developmental research, taking inspiration from existing open-science practices and providing examples from recent and ongoing studies. By embracing a scientific culture where descriptive research and open science coexist productively, developmental science will be better positioned to generate comprehensive theories of development and understand variability in development across communities and cultures.

The Pull-to-Sit Task: Examining Infant Postural Development in Autism Spectrum Disorder.

OBJECTIVE: To evaluate the predictive relationship between early trajectories of postural and head control during a pull-to-sit task and later autism diagnostic and developmental outcomes. STUDY DESIGN: Using a prospective longitudinal design, postural skills of 100 infants at elevated and low familial likelihood of autism spectrum disorder (ASD) were evaluated using a pull-to-sit task monthly from age 1 month to 6 months. At age 24 months, infants were seen for a developmental and diagnostic evaluation completed by examiners masked to participant group. Latent growth curve models were used to compare early trajectories of pull-to-sit performance in infants later diagnosed with ASD and typically developing infants and to predict developmental outcomes. RESULTS: Pull-to-sit trajectories did not differ in infants with an elevated likelihood of ASD or infants with ASD compared with low-likelihood and typically developing infants, but infants with ASD were more likely to exhibit a head lag by age 4 months. In addition, pull-to-sit trajectories were predictive of social and speech skills 2 years later. CONCLUSIONS: These findings highlight the link between very early pull-to-sit skills and later social and language outcomes. Atypical postural development and persistent presence of head lag may be important early indicators of social and language vulnerabilities, including ASD.

Visual Perception Is Highly Flexible and Context Dependent in Young Infants: A Case of Top-Down-Modulated Motion Perception.

Top-down modulation is an essential cognitive component in human perception. Despite mounting evidence of top-down perceptual modulation in adults, it is largely unknown whether infants can engage in this cognitive function. Here, we examined top-down modulation of motion perception in 6- to 8-month-old infants (recruited in North America) via their smooth-pursuit eye movements. In four experiments, we demonstrated that infants' perception of motion direction can be flexibly shaped by briefly learned predictive cues when no coherent motion is available. The current findings present a novel insight into infant perception and its development: Infant perceptual systems respond to predictive signals engendered from higher-level learning systems, leading to a flexible and context-dependent modulation of perception. This work also suggests that the infant brain is sophisticated, interconnected, and active when placed in a context in which it can learn and predict.

Investigating the development of the autonomic nervous system in infancy through pupillometry.

We aim to investigate early developmental trajectories of the autonomic nervous system (ANS) as indexed by the pupillary light reflex (PLR) in infants with (i.e. preterm birth, feeding difficulties, or siblings of children with autism spectrum disorder) and without (controls) increased likelihood for atypical ANS development. We used eye-tracking to capture the PLR in 216 infants in a longitudinal follow-up study spanning 5 to 24 months of age, and linear mixed models to investigate effects of age and group on three PLR parameters: baseline pupil diameter, latency to constriction and relative constriction amplitude. An increase with age was found in baseline pupil diameter (F(3,273.21) = 13.15, p < 0.001, [Formula: see text] = 0.13), latency to constriction (F(3,326.41) = 3.84, p = 0.010, [Formula: see text] = 0.03) and relative constriction amplitude(F(3,282.53) = 3.70, p = 0.012, [Formula: see text] = 0.04). Group differences were found for baseline pupil diameter (F(3,235.91) = 9.40, p < 0.001, [Formula: see text] = 0.11), with larger diameter in preterms and siblings than in controls, and for latency to constriction (F(3,237.10) = 3.48, p = 0.017, [Formula: see text] = 0.04), with preterms having a longer latency than controls. The results align with previous evidence, with development over time that could be explained by ANS maturation. To better understand the cause of the group differences, further research in a larger sample is necessary, combining pupillometry with other measures to further validate its value.

Plasmodium falciparum infection and disease in infancy associated with increased risk of malaria and anaemia in childhood.

BACKGROUND: Infants under 6 months of age are often excluded from malaria surveillance and observational studies. The impact of malaria during early infancy on health later in childhood remains unknown. METHODS: Infants from two birth cohorts in Malawi were monitored at quarterly intervals and whenever they were ill from birth through 24 months for Plasmodium falciparum infections and clinical malaria. Poisson regression and linear mixed effects models measured the effect of exposure to malaria in infancy on subsequent malaria incidence, weight-for-age z-scores (WAZ), and haemoglobin concentrations after 6 months. RESULTS: Infants with at least one P. falciparum infection during their first 6 months had increased incidence ratio (IRR) of P. falciparum infection (IRR = 1.27, 95% CI, 1.06-1.52) and clinical malaria (IRR = 2.37, 95% CI, 2.02-2.80) compared to infants without infection. Infants with clinical malaria had increased risk of P. falciparum infection incidence between 6 and 24 months (IRR = 1.64, 95% CI, 1.38-1.94) and clinical malaria (IRR = 1.85, 95% CI, 1.48-2.32). Exposure to malaria was associated with lower WAZ over time (p = 0.02) and lower haemoglobin levels than unexposed infants at every time interval (p = 0.02). CONCLUSIONS: Infants experiencing malaria infection or clinical malaria are at increased risk of subsequent infection and disease, have poorer growth, and lower haemoglobin concentrations.

The home literacy environment mediates effects of socio-economic status on infant vocabulary development.

It is well attested that high socio-economic status (SES) is associated with larger vocabulary size estimates in young children. This has led to growing interest in identifying associations and mechanisms that may contribute to this relationship. In this study, parent-child reading behaviors were investigated in relation to vocabulary size in a large-scale study of linguistically and socio-economically diverse families. This study sampled 902 infants in Singapore, a multilingual society. Both single-language (dominant and non-dominant) and dual-language vocabulary size estimates were obtained and related to family SES, demographic details, and home literacy activities. Results demonstrated that both single-language (dominant and non-dominant) and dual-language infant vocabulary size estimates were predicted by parental education levels. Further analyses revealed that parent-child book reading activities mediated the relationship between parental education and infant vocabulary size. Findings suggest that shared book reading may narrow effects of socio-economic disparities on early language development. RESEARCH HIGHLIGHTS: Socio-economic status (SES) was examined in relation to infant vocabulary size in a linguistically and socio-economically diverse setting. Mediating effects of the home literacy environment on infant vocabulary size were measured. Socio-economic factors, notably parental education, had both direct and indirect effects on vocabulary size. The home literacy environment mediated effects of SES on infant vocabulary size.

A concert for babies: Attentional, affective, and motor responses in an infant audience.

Many of our most powerful musical experiences are shared with others, and researchers have increasingly investigated responses to music in group contexts. Though musical performances for infants are growing in popularity, most research on infants' responses to live music has focused on solitary caregiver-infant pairs. Here, we report infants' attentional, affective, and motor responses to live music as audience members. Two groups of caregiver-infant (6-18 months) pairs (50 total) watched a short musical performance with two song styles - lullaby and playsong. Caregivers were instructed to watch passively or interactively. The playsong captured more infant attention and, especially in the interactive condition, elicited more infant smiles. Notably, infant attention was more coordinated with their own caregiver than a random caregiver, and infants with no experience attending group musical events in the past were especially attentive to the performance. Infants were more likely to generate movements when parents remained still. Overall, infants' responses to live musical performance in an audience were influenced by song style, caregiver behavior, and their own musical histories. A video abstract of this article can be viewed at https://www.youtube.com/watch?v=q61qnDMW8dU. RESEARCH HIGHLIGHTS: Infants' responses to live musical performances are shaped by the music, by their caregivers, and by their own musical histories During a concert for babies, a playsong more effectively elicited infant attention and smiles than a lullaby, especially when caregivers were interactive Infant attention was more coordinated with their own caregiver than with other caregivers watching the same show.

Dynamical systems model of development of the action differentiation in early infancy: a requisite of physical agency.

Young infants are sensitive to whether their body movements cause subsequent events or not during the interaction with the environment. This ability has been revealed by empirical studies on the reinforcement of limb movements when a string is attached between an infant limb and a mobile toy suspended overhead. A previous study reproduced the experimental observation by modeling both the infant's limb and a mobile toy as a system of coupled oscillators. The authors then argued that emergence of agency could be explained by a phase transition in the dynamical system: from a weakly coupled state to a state where the both movements of the limb and the toy are highly coordinated. However, what remains unexplained is the following experimental observation: When the limb is connected to the mobile toy by a string, the infant increases the average velocity of the arm's movement. On the other hand, when the toy is controlled externally, the average arm's velocity is greatly reduced. Since young infants produce exuberant spontaneous movements even with no external stimuli, the inhibition of motor action to suppress the formation of spurious action-perception coupling should be also a crucial sign for the emergence of agency. Thus, we present a dynamical system model for the development of action differentiation, to move or not to move, in the mobile task. In addition to the pair of limb and mobile oscillators for providing positive feedback for reinforcement in the previous model, bifurcation dynamics are incorporated to enhance or inhibit self-movements in response to detecting contingencies between the limb and mobile movements. The results from computer simulations reproduce experimental observations on the developmental emergence of action differentiation between 2 and 3 months of age in the form of a bifurcation diagram. We infer that the emergence of physical agency entails young infants' ability not only to enhance a specific action-perception coupling, but also to decouple it and create a new mode of action-perception coupling based on the internal state dynamics with contingency detection between self-generated actions and environmental events.