A cross-cultural comparison of the development of the social smile: a longitudinal study of maternal and infant imitation in 6- and 12-week-old infants

Evaluating caregiver-child interactions in low- and middle-income countries: a systematic review of tools and methods

AIMS/BACKGROUND

The United Nations Sustainable Development Goals (SDGs) has placed emphasis on improving early child development globally. This is supported through the Nurturing Care Framework which includes responsive caregiving. To evaluate responsive caregiving, tools to assess quality of caregiver-child interactions are used, however there is little information on how they are currently employed and/or adapted particularly in low- and middle-income countries (LMICs) where children have a greater risk of adverse outcomes. The aim of this review is to provide a comprehensive guide on methodologies used to evaluate caregiver-child interaction - including their feasibility and cultural adaptation.

DESIGN/METHODS

We conducted a systematic review of studies over 20years in LMICs which assessed caregiver-child interactions. Characteristics of each tool, their validity (assessed with COSMIN Risk of Bias checklist), and the quality of the study (Mixed Methods Appraisal Tool) are reported.

RESULTS

We identified 59 studies using 34 tools across 20 different LMICs. Most tools (86.5%) employed video-recorded observations of caregiver-child interactions at home (e.g. Ainsworth's Sensitivity Scale, OMI) or in the laboratory (e.g. PICCOLO) with a few conducting direct observations in the field (e.g. OMCI, HOME); 13.5% were self-reported. Tools varied in methodology with limited or no mention of validity and reliability. Most tools are developed in Western countries and have not been culturally validated for use in LMIC settings.

CONCLUSION

There are limited caregiver-child interaction measures used in LMIC settings, with only some locally validated locally. Future studies should aim to ensure better validity, applicability and feasibility of caregiver-child interaction tools for global settings.

A longitudinal comparison of maternal behaviour in German urban humans (Homo sapiens) and captive chimpanzees (Pan troglodytes)

Comparative perspectives are crucial in the study of human development, yet longitudinal comparisons of humans and other primates are still relatively uncommon. Here, we combined theoretical frameworks from cross-cultural and comparative psychology, to study maternal style in 10 mother-infant pairs of German urban humans (Homo sapiens) and 10 mother-infant pairs of captive chimpanzees (Pan troglodytes), during the first year of infants' development. We conducted focal observations of different behaviours (i.e. nursing, carrying, body contact, touching, grooming, restraining, approaching, leaving, rejection, aggression, mutual gaze, object stimulation), during natural interactions. Analyses revealed a more distal maternal style in WEIRD humans than in captive chimpanzees, with different behaviours being generally more common in one of the two species throughout development. For other behaviours (i.e. nursing), developmental trajectories differed between WEIRD humans and captive chimpanzees, although differences generally decreased through infants' development. Overall, our study confirms functional approaches as a valid tool for comparative longitudinal studies.

Similarities and differences in the functional architecture of mother- infant communication in rhesus macaque and British mother-infant dyads

Similarly to humans, rhesus macaques engage in mother-infant face-to-face interactions. However, no previous studies have described the naturally occurring structure and development of mother-infant interactions in this population and used a comparative-developmental perspective to directly compare them to the ones reported in humans. Here, we investigate the development of infant communication, and maternal responsiveness in the two groups. We video-recorded mother-infant interactions in both groups in naturalistic settings and analysed them with the same micro-analytic coding scheme. Results show that infant social expressiveness and maternal responsiveness are similarly structured in humans and macaques. Both human and macaque mothers use specific mirroring responses to specific infant social behaviours (modified mirroring to communicative signals, enriched mirroring to affiliative gestures). However, important differences were identified in the development of infant social expressiveness, and in forms of maternal responsiveness, with vocal responses and marking behaviours being predominantly human. Results indicate a common functional architecture of mother-infant communication in humans and monkeys, and contribute to theories concerning the evolution of specific traits of human behaviour.

Infant visual preference for the mother's face and longitudinal associations with emotional reactivity in the first year of life

Past research has focused on infants' visual preference for the mother's face, however it is still unknown how these responses change over time and what factors associate with such changes. A longitudinal study (N ~ 60) was conducted to investigate the trajectories of infant visual preference for the mother's face and how these are related to the development of emotional reactivity in the first year of life. Two face stimuli (i.e., the infant's mother and a consistent stranger face) were used in a visual preference task at 2 weeks, 4, 6, and 9 months of age. At each time point, mothers were asked to complete a measure of infant temperament via standardised questionnaires. Our results show that while at 2 weeks, 4 months and 9 months of age infants looked equally at both faces, infants at 6 months looked significantly longer at their mother's face. We also observed prospective associations with emotional reactivity variables so that infants who looked longer at the mother's face at 6 months showed higher falling reactivity, i.e. a better ability to recover from distress, at 9 months. We discuss these findings in light of the roles that both infant development and the caregiver play in emerging emotion regulation capacities during the first year of life.

Intentional Understanding Through Action Coordination in Early Triadic Interactions

The ability to understand the behaviour of other people in intentional terms has been traditionally explained by resorting to inferential mechanisms that would allow individuals to access the internal mental states of others. In recent years, the second-person perspective has established itself as a theoretical alternative to traditional models. It argues that intentional understanding is an embodied, natural, and immediate process that occurs in situations such as face-to-face early dyadic interactions between adults and infants. In this article, we argue that the way in which the second-person perspective regards body and object is problematic. Based on psychological evidence that demonstrates the constitutive role of the body and objects for cognitive development, we propose the foundations of an ecological-enactive, semiotic and pragmatic model of intentional understanding. We argue that intentional understanding should be conceived as the skilful coordination of behaviours that subjects come to enact in interactive settings, following the dynamics of bodily and material practices that have acquired normative force over time.

Universality without uniformity - infants' reactions to unresponsive partners in urban Germany and rural Ecuador

Previous studies based on non-WEIRD (Western, Educated, Industrialized, Rich, and Democratic) samples provide initial evidence that the still-face effect is universal. Based on the assumption that - independent of their cultural niches - infants share some fundamental expectations of social interactions, we put forth the assumption that a universal response exists for when a social interaction is interrupted. At the same time, we hypothesized that the size of the effect depends on the typicality of the interaction that precedes the adult partners' interruption. To test these hypotheses, we conducted the Still-Face Paradigm (SFP) with infants (3- and 4.5-month-olds) from two cultural milieus, namely Münster (urban Germany) and the Kichwa ethnic group from the northern Andes region (rural Ecuador), as these contexts presumably offer different ways of construing the self that are associated with different parenting styles, namely distal and proximal parenting. Furthermore, we developed a paradigm that comes much closer to the average expected environment of Kichwa infants, the "No-Touch Paradigm" (NTP). Overall, the results support our initial hypothesis that the still-face effect is universal. Moreover, infants from both cultural milieus responded to the no-touch condition with a change in negative affect. At the same time, some of the infants' responses were accentuated in a culture-specific way: Kichwa infants had a stronger response to an interruption of proximal interaction patterns during the NTP. While our findings underline infants' universal predisposition for face-to-face interaction, they also suggest that cultural differences in internalized interactions do influence infant behavior and experience and, in turn, development.

The cultural specificity of parent-infant interaction: Perspectives of urban middle-class and rural indigenous families in Costa Rica

Caregiver-infant interactions in Western middle class often take place in dyadic play settings, engaged in infant-initiated object stimulation, and surrounded by a positive emotional tone, reflecting a distal parenting style. With this study we aim to investigate whether the same conception of caregiver-infant interaction is embodied in the proximal parenting style. For this purpose, we compare the context and pattern of caregiver-infant interactions in two cultural groups in Costa Rica: Urban middle-class families in San José and rural indigenous Bribri families. Naturalistic observations and caregiver interviews revealed significant differences between the groups, with San José families resembling the Western middle-class interaction pattern. Among the Bribris, adult-child play is uncommon so that children interact with adults in primary care settings and with older siblings in play settings. Bribri interactions are further characterized by emotional neutrality. The groups did not differ in terms of body contact. Also, caregivers in both samples took the lead in interactions more often than infants. The results are discussed in the context of an autonomous-relational style as combining psychological autonomy and hierarchical relatedness. We argue that early childhood theories and intervention programs need to abandon the assumption that Western middle-class strategies are universal and recognize locally relevant patterns of caregiver-infant interaction.

Six facial prosodic expressions caregivers similarly display to infants and dogs

Parents tend to use a specific communication style, including specific facial expressions, when speaking to their preverbal infants which has important implications for children's healthy development. In the present study, we investigated these facial prosodic features of caregivers with a novel method that compares infant-, dog- and adult-directed communication. We identified three novel facial displays in addition to the already described three facial expressions (i.e. the 'prosodic faces') that mothers and fathers are typically displaying when interacting with their 1-18 month-old infants and family dogs, but not when interacting with another adult. The so-called Special Happy expression proved to be the most frequent face type during infant- and dog-directed communication which always includes a Duchenne marker to convey an honest and intense happy emotion of the speaker. These results suggest that the 'prosodic faces' play an important role in both adult-infant and human-dog interactions and fulfil specific functions: to call and maintain the partner's attention, to foster emotionally positive interactions, and to strengthen social bonds. Our study highlights the relevance of future comparative studies on facial prosody and its potential contribution to healthy emotional and cognitive development of infants.

Mother-infant co-regulation from 0 to 2 years: The role of copy behaviors. A systematic review

The purpose of this review was twofold: (1) to examine how copy behaviors (CB) have been studied in mother-infant natural interactions from 0 to 24 months, and (2) to determine to what extent they can be considered co-regulation processes between both members of the dyad. To do this, 36 studies published between 1975 and 2021 were systematically examined, classified and discussed. The analyzed evidence showed that CB in spontaneous mother-infant interactions have been examined under different perspectives, that such behaviors might be differentially classified as distinct modes of copying according to their traits and, lastly, that CB operate as social facilitators that foster the co-regulation of both affects and behaviors and direct mothers and infants, most of the times, towards a mutual sense of interpersonal matching that adds quality to their interactions.

Still-face redux: Infant responses to a classic and modified still-face paradigm in proximal and distal care cultures

Literature on infant emotion is dominated by research conducted in Western, industrialized societies where early socialization is characterized by face-to-face, vocal communication with caregivers. There is a dearth of knowledge of infant emotion in the context of social interaction outside of the visual and vocal modalities. In a three-population cross-cultural comparison, we used the still-face task to measure variation in behavior among infants from proximal care (practicing high levels of physical contact) communities in Bolivia and distal care (emphasizing vocal and visual interaction) communities in the U.S. and Fiji. In a modified version of the face-to-face still-face (FFSF), Study 1, infants in the U.S. and Fiji displayed the typical behavioral response to the still-face episode: increased negative affect and decreased social engagement, whereas infants in Bolivia showed no change. For tactile behavior, infants in Bolivia showed an increase in tactile self-stimulation from the interaction episode to the still-face episode, whereas U.S. infants showed no change. In Study 2, we created a novel body-to-body version of the still-face paradigm ("still-body") with infants in US and Bolivia, to mimic the near-constant physical contact Bolivian infants experience. The U.S. and Bolivian infant response was similar to Study 1: US infants showed decreased positive affect and increased negative affect and decreased social engagement from the interaction to the still-body episode and Bolivian infants showed no change. Notably, there were overall differences in infant behaviors between the two paradigms (FFSF and Still-Body). Infants in Bolivia and the U.S. showed increased positive facial affect during the FFSF paradigm in comparison with the Still-Body paradigm. Our results demonstrate the need for more globally representative developmental research and a broader approach to infant emotion and communication.

Maternal Ethnotheories About Infants’ Ideal States in Two Cultures

Accumulating evidence suggests that ethnotheories about ideal states of infant affect and activity vary across cultures in important ways. However, most previous studies have not directly identified such ethnotheories but rather inferred them from observational studies on mother-infant interaction. To fill this research gap, we interviewed mothers from two cultural milieus—mothers from Münster (urban Germany) and mothers who identify themselves as Kichwas (rural Ecuador), as these contexts presumably offer different construals of the self—to determine their ideal states of infant affect and activity and their self-reported co-regulation tendencies. The interview was based on short video clips of a German and an Ecuadorian infant displaying different combinations of affect (neutral, low-arousal positive or high-arousal positive affect) and activity (low or high). As expected, mothers in Münster preferred higher levels of positive affect than Kichwa mothers. Regarding co-regulation tendencies, we found cultural similarities and differences: Across samples, mothers tended to stimulate affect, and activity, especially when infants were neutral or inactive, but differed in their modality of co-regulation. More specifically, Münster mothers advocated more distal co-regulation modalities than did the Kichwa mothers. Taken together, the present study is the first to provide explicit evidence that maternal ethnotheories about infants’ ideal affect vary across cultures. The cross-cultural differences in ideal affect were not accompanied by differences in self-reported co-regulation of affect, suggesting an indirect link between ideals and (self-reported) parenting behavior.

Sharing Experiences in Infancy: From Primary Intersubjectivity to Shared Intentionality

We contrast two theses that make different assumptions about the developmental onset of human-unique sociality. The primary intersubjectivity thesis (PIT) argues that humans relate to each other in distinct ways from the beginning of life, as is shown by newborns' participation in face-to-face encounters or "primary intersubjectivity." According to this thesis, humans' innate relational capacity is the seedbed from which all subsequent social-emotional and social-cognitive developments continuously emerge. The shared intentionality thesis (SIT) states that human-unique forms of interaction develop at 9-12 months of age, when infants put their heads together with others in acts of object-focused joint attention and simple collaborative activities. According to this thesis, human-unique cognition emerges rapidly with the advent of mind-reading capacities that evolved specifically for the purpose of coordination. In this paper, we first contrast the two theses and then sketch the outlines of an account that unifies their strengths. This unified account endorses the PIT's recognition of the fundamental importance of primary intersubjectivity. Any act of sharing experiences is founded on the communicative capacity that is already displayed by young infants in primary intersubjectivity. At the same time, we question the PIT's interpretation that dyadic encounters have the triadic structure of joint attention. Lastly, we draw on empirical work on the development of joint attention, imitation, and social referencing that serves as evidence that primary intersubjectivity continuously unfolds into the capacity for triadic joint attention.

Superior Detection of Faces in Male Infants at 2 Months

Females generally attend more to social information than males; however, little is known about the early development of these sex differences. With eye tracking, 2-month olds' (N = 101; 44 females) social orienting to faces was measured within four-item image arrays. Infants were more likely to detect human faces compared to objects, suggesting a functional face detection system. Unexpectedly, males looked longer at human faces than females, and only males looked faster and longer at human faces compared to objects. Females, in contrast, looked less at human faces relative to animal faces and objects, appearing socially disinterested. Notably, this is the first report of a male face detection advantage at any age. These findings suggest a unique stage in early infant social development.

The social-emotional functioning of young children with a significant cognitive and motor developmental delay

Children with a significant cognitive and motor developmental delay (SDD) are vulnerable for the development of (future) behavioral and mental health problems. This paper aims to assess the social-emotional functioning of these children, both globally and in various domains. Semi-structured interviews with one or more primary caregiver(s) of 45 children were conducted and analyzed on 13 domains of social-emotional functioning, according to the Scale for Emotional Development - Revised (SED-R). The SED-R scoring system was slightly adapted in the current study in order to elucidate more subtle differences between children. A general delayed social-emotional development was found, with children functioning within different phases across domains and certain domains generally showing higher or lower scores. To capture the emotional needs of children with SDD, a more disaggregated scoring system seems valuable so that both the global level and the level per domain can be taken in consideration in designing interventions.

Culture and early social-cognitive development

From a developmental systems perspective, this chapter focuses on the question whether culture matters for children's early social-cognitive development. Based on a review of the current cross-cultural literature, we evaluate the current state of research on cross-cultural similarities and differences in major developmental milestones of early social cognition, namely (i) the development of self-awareness and an understanding of self and others as intentional agents, (ii) advanced forms of social learning and (iii) prosocial cognition and behavior. Overall, the current cross-cultural research suggests universality without uniformity: the common suite of social-cognitive skills emerges reliably and, at the same time, there are culture-specific accentuations of social-cognitive development across domains that mostly are in line with cultural values, beliefs and practices. By following different agendas when providing and structuring physical and social settings for their children, caregivers coherently organize infants' nascent intuitions, sentiments, and inclinations into increasingly coherent patterns of attention, appraisal, experience and behavior that are in line with cultural ideals and beliefs. By doing so, culturally informed social interaction sets the stage for culture-specific modulations of social cognition already in the first years of life.

Maternal postpartum depression is a risk factor for infant emotional variability at 4 months

Maternal postpartum depression (PPD) is a risk for disruption of mother-infant interaction. Infants of depressed mothers have been found to display less positive, more negative, and neutral affect. Other studies have found that infants of mothers with PPD inhibit both positive and negative affect. In a sample of 28 infants of mothers with PPD and 52 infants of nonclinical mothers, we examined the role of PPD diagnosis and symptoms for infants' emotional variability, measured as facial expressions, vocal protest, and gaze using microanalysis, during a mother-infant face-to-face interaction. PPD symptoms and diagnosis were associated with (a) infants displaying fewer high negative, but more neutral/interest facial affect events, and (b) fewer gaze off events.  PPD diagnosis, but not symptoms, was associated with less infant vocal protest. Total duration of seconds of infant facial affective displays and gaze off was not related to PPD diagnosis or symptoms, suggesting that when infants of depressed mothers display high negative facial affect or gaze off, these expressions are more sustained, indicating lower infant ability to calm down and re-engage, interpreted as a disturbance in self-regulation. The findings highlight the importance of not only examining durations, but also frequencies, as the latter may inform infant emotional variability.

The effect of mother-infant skin-to-skin contact on Ghanaian infants' response to the Still Face Task: Comparison between Ghanaian and Canadian mother-infant dyads

The effect of mother-infant skin-to-skin contact on Ghanaian infants' developing social expectations for maternal behavior was investigated. Infants with high and low mother-infant skin-to-skin contact experience in the infants' first month engaged with their mothers in a Still Face Task at 6 weeks of age. Infants with high skin-to-skin contact experience, but not those with low skin-to-skin contact experience, demonstrated the still face effect with their smiles. Infants with both high and low skin-to-skin contact experience demonstrated the still face effect with their visual attention. The behaviors of the Ghanaian infants and their mothers during the task were compared to archival evidence of Canadian mother-infant dyads' behaviors in skin-to-skin and control groups who engaged in the Still Face Task at the infant ages of 1 and 2 months. Similarities and differences between the behaviors of the mother-infant dyads in the two cultures were assessed.

Mapping the Passions: Toward a High-Dimensional Taxonomy of Emotional Experience and Expression

What would a comprehensive atlas of human emotions include? For 50 years, scientists have sought to map emotion-related experience, expression, physiology, and recognition in terms of the "basic six"-anger, disgust, fear, happiness, sadness, and surprise. Claims about the relationships between these six emotions and prototypical facial configurations have provided the basis for a long-standing debate over the diagnostic value of expression (for review and latest installment in this debate, see Barrett et al., p. 1). Building on recent empirical findings and methodologies, we offer an alternative conceptual and methodological approach that reveals a richer taxonomy of emotion. Dozens of distinct varieties of emotion are reliably distinguished by language, evoked in distinct circumstances, and perceived in distinct expressions of the face, body, and voice. Traditional models-both the basic six and affective-circumplex model (valence and arousal)-capture a fraction of the systematic variability in emotional response. In contrast, emotion-related responses (e.g., the smile of embarrassment, triumphant postures, sympathetic vocalizations, blends of distinct expressions) can be explained by richer models of emotion. Given these developments, we discuss why tests of a basic-six model of emotion are not tests of the diagnostic value of facial expression more generally. Determining the full extent of what facial expressions can tell us, marginally and in conjunction with other behavioral and contextual cues, will require mapping the high-dimensional, continuous space of facial, bodily, and vocal signals onto richly multifaceted experiences using large-scale statistical modeling and machine-learning methods.

Emotional Expressions Reconsidered: Challenges to Inferring Emotion From Human Facial Movements

It is commonly assumed that a person's emotional state can be readily inferred from his or her facial movements, typically called emotional expressions or facial expressions. This assumption influences legal judgments, policy decisions, national security protocols, and educational practices; guides the diagnosis and treatment of psychiatric illness, as well as the development of commercial applications; and pervades everyday social interactions as well as research in other scientific fields such as artificial intelligence, neuroscience, and computer vision. In this article, we survey examples of this widespread assumption, which we refer to as the common view, and we then examine the scientific evidence that tests this view, focusing on the six most popular emotion categories used by consumers of emotion research: anger, disgust, fear, happiness, sadness, and surprise. The available scientific evidence suggests that people do sometimes smile when happy, frown when sad, scowl when angry, and so on, as proposed by the common view, more than what would be expected by chance. Yet how people communicate anger, disgust, fear, happiness, sadness, and surprise varies substantially across cultures, situations, and even across people within a single situation. Furthermore, similar configurations of facial movements variably express instances of more than one emotion category. In fact, a given configuration of facial movements, such as a scowl, often communicates something other than an emotional state. Scientists agree that facial movements convey a range of information and are important for social communication, emotional or otherwise. But our review suggests an urgent need for research that examines how people actually move their faces to express emotions and other social information in the variety of contexts that make up everyday life, as well as careful study of the mechanisms by which people perceive instances of emotion in one another. We make specific research recommendations that will yield a more valid picture of how people move their faces to express emotions and how they infer emotional meaning from facial movements in situations of everyday life. This research is crucial to provide consumers of emotion research with the translational information they require.

Beyond aerodigestion: Exaptation of feeding-related mouth movements for social communication in human and nonhuman primates

Three arguments are advanced from human and nonhuman primate infancy research for the exaptation of ingestive mouth movements (tongue protrusion and lip smacking) for the purposes of social communication: their relation to affiliative behaviours, their sensitivity to social context, and their role in social development. Although these behaviours may have an aerodigestive function, such an account of their occurrence is only partial.

The Effects of Maternal Mirroring on the Development of Infant Social Expressiveness: The Case of Infant Cleft Lip

Parent-infant social interactions start early in development, with infants showing active communicative expressions by just two months. A key question is how this social capacity develops. Maternal mirroring of infant expressions is considered an important, intuitive, parenting response, but evidence is sparse in the first two months concerning the conditions under which mirroring occurs and its developmental sequelae, including in clinical samples where the infant's social expressiveness may be affected. We investigated these questions by comparing the development of mother-infant interactions between a sample where the infant had cleft lip and a normal, unaffected, comparison sample. We videotaped dyads in their homes five times from one to ten weeks and used a microanalytic coding scheme for maternal and infant behaviours, including infant social expressions, and maternal mirroring and marking responses. We also recorded maternal gaze to the infant, using eye-tracking glasses. Although infants with cleft lip did show communicative behaviours, the rate of their development was slower than in comparison infants. This group difference was mediated by a lower rate of mirroring of infant expressions by mothers of infants with cleft lip; this effect was, in turn, partly accounted for by reduced gaze to the infant's mouth, although the clarity of infant social expressions (indexed by cleft severity) and maternal self-blame regarding the cleft were also influential. Results indicate the robustness of parent-infant interactions but also their sensitivity to specific variations in interactants' appearance and behaviour. Parental mirroring appears critical in infant social development, likely supported by the mirror neuron system and underlying clinical and, possibly, cultural differences in infant behaviour. These findings suggest new avenues for clinical intervention.

The Ontogeny of Human Self-Consciousness

Self-consciousness is an essential characteristic of what it means to be human and is arguably a unique adaptation of our species. Human self-consciousness is construed here as the propensity to perceive and be aware of oneself not only for oneself, but also through the evaluative eyes of other individuals. The origins and determinants of this characteristic remain wide-open questions. I propose a developmental account and suggest possible new directions in the investigation of genetic, brain, and cultural factors that play a role in the ontogeny of human self-conscious psychology.

Social Origins of Cortical Face Areas

Recently acquired fMRI data from human and macaque infants provide novel insights into the origins of cortical networks specialized for perceiving faces. Data from both species converge: cortical regions responding preferentially to faces are present and spatially organized early in infancy, although fully selective face areas emerge much later. What explains the earliest cortical responses to faces? We review two proposed mechanisms: proto-organization for simple shapes in visual cortex, and an innate subcortical schematic face template. In addition, we propose a third mechanism: infants choose to look at faces to engage in positively valenced, contingent social interactions. Activity in medial prefrontal cortex during social interactions may, directly or indirectly, guide the organization of cortical face areas.

When dyadic interaction is the context: Mimicry behaviors on the origin of imitation

Keven & Akins (K&A) redefine some of the neonatal imitation (NI) behaviors as developmental stereotypes. From a neuroconstructivist framework, those early gestures are also far from being considered as imitative behaviors. The cognitive substrate of imitation requires an interactive context to develop. Prior to intentional imitation, the dyad shows mimicry behaviors, which are automatic, but do not fade through development.

Less Empathic and More Reactive: The Different Impact of Childhood Maltreatment on Facial Mimicry and Vagal Regulation

Facial mimicry and vagal regulation represent two crucial physiological responses to others' facial expressions of emotions. Facial mimicry, defined as the automatic, rapid and congruent electromyographic activation to others' facial expressions, is implicated in empathy, emotional reciprocity and emotions recognition. Vagal regulation, quantified by the computation of Respiratory Sinus Arrhythmia (RSA), exemplifies the autonomic adaptation to contingent social cues. Although it has been demonstrated that childhood maltreatment induces alterations in the processing of the facial expression of emotions, both at an explicit and implicit level, the effects of maltreatment on children's facial mimicry and vagal regulation in response to facial expressions of emotions remain unknown. The purpose of the present study was to fill this gap, involving 24 street-children (maltreated group) and 20 age-matched controls (control group). We recorded their spontaneous facial electromyographic activations of corrugator and zygomaticus muscles and RSA responses during the visualization of the facial expressions of anger, fear, joy and sadness. Results demonstrated a different impact of childhood maltreatment on facial mimicry and vagal regulation. Maltreated children did not show the typical positive-negative modulation of corrugator mimicry. Furthermore, when only negative facial expressions were considered, maltreated children demonstrated lower corrugator mimicry than controls. With respect to vagal regulation, whereas maltreated children manifested the expected and functional inverse correlation between RSA value at rest and RSA response to angry facial expressions, controls did not. These results describe an early and divergent functional adaptation to hostile environment of the two investigated physiological mechanisms. On the one side, maltreatment leads to the suppression of the spontaneous facial mimicry normally concurring to empathic understanding of others' emotions. On the other side, maltreatment forces the precocious development of the functional synchronization between vagal regulation and threatening social cues facilitating the recruitment of fight-or-flight defensive behavioral strategies.

Different kinds of infants' smiles in the first six months and contingency to maternal affective behavior

Infants' smiling is considered an expression of affection, and an index of cognitive and socio-emotional development. Despite research advances in this area, there is much to explore on the ontogeny of smiling, its meaning and the context in which it is manifested early in life. This study aimed at: (a) investigating smiling patterns in these different developmental moments in early infancy, (b) analyzing patterns of association between babies' smiles and their mothers' affective behaviors, and (c) verifying whether babies can answer contingently, with smiles, to mothers' affective behaviors. Participants were sixty Brazilian mother-infant dyads. Infants in three age levels (one, three, and five months of age) and their mothers were observed. They were videotaped at home, during 20 minutes in free sessions. The results indicate increase in frequency of infants' smiling instances across ages (F(2, 59) = 9.18, p < .05), variations in the frequency of maternal behaviors accompanying the variations in infants' smiling (F(2, 59) = 6.03, p < .05), correlations between infants' smiling and mothers' affective behaviors, and contingency between the behaviors of both mothers and infants. It was verified a strong association between mothers' behavior and their babies' smiles, emphasizing the importance of affective interactions in early stages of development.

A graphical user interface for infant ERP analysis

Recording of event-related potentials (ERPs) is one of the best-suited technologies for examining brain function in human infants. Yet the existing software packages are not optimized for the unique requirements of analyzing artifact-prone ERP data from infants. We developed a new graphical user interface that enables an efficient implementation of a two-stage approach to the analysis of infant ERPs. In the first stage, video records of infant behavior are synchronized with ERPs at the level of individual trials to reject epochs with noncompliant behavior and other artifacts. In the second stage, the interface calls MATLAB and EEGLAB (Delorme & Makeig, Journal of Neuroscience Methods 134(1):9–21, 2004) functions for further preprocessing of the ERP signal itself (i.e., filtering, artifact removal, interpolation, and rereferencing). Finally, methods are included for data visualization and analysis by using bootstrapped group averages. Analyses of simulated and real EEG data demonstrated that the proposed approach can be effectively used to establish task compliance, remove various types of artifacts, and perform representative visualizations and statistical comparisons of ERPs. The interface is available for download from http://www.uta.fi/med/icl/methods/eeg.html in a format that is widely applicable to ERP studies with special populations and open for further editing by users.

The Emergence of Social Smiling

The study addresses the emergence of the social smile in two different sociocultural contexts during the first 12 postnatal weeks. We examined different eliciting mechanisms like mutual gazing, maternal smile during mutual gazing, and reciprocal maternal and infant imitation of smiling. In co-constructivist theories of emotional development, all of them are considered social mechanisms that foster the emergence of social smile in early infancy around the 2-month shift. During the 6th postnatal week, we assumed that mutual gazing and the accompanying maternal smiles are the primary mechanisms that correspond with first infants’ social smile. From the 2-month shift onward, thus during the 8th, 10th, and 12th postnatal weeks, we assumed maternal imitation of infant smile moderates the positive relationship between infant imitation of maternal smile and the duration of infant social smile. We compared face-to-face interactions between 20 mother–child dyads from an independent sociocultural context (urban middle-class families from Münster, Germany) and 24 mother–child dyads from an interdependent sociocultural context (rural Nso families, Cameroon) when the infants were 6, 8, 10, and 12 weeks old. The first hypothesis could be corroborated for both cultural contexts, the second hypothesis only partly for the independent cultural contexts and staggered for the interdependent context. The consequences of culture-specific developmental pathways of social smile are discussed.