Inferring the goals of other people's actions is an important aspect of early social cognitive development. Using an experimental manipulation, we investigated the role of infant motor processes in the processing of action they see performed by another person. We designed a procedure in which we inhibited infants' concurrent access to motor representations of precision grasping as they observed the reach-to-grasp action of an adult experimenter. In a within-subjects design, 48 12-month-olds watched adult reach-to-grasp actions under two conditions of hand posture in randomly-assigned order: (a) hands free and (b) hands constrained in a manner that blocked their grip formation. Infant looking times were measured as an experimenter reached toward large and small objects, using a power or precision grip type. Infants' prior-existing fine motor skills were assessed using a standardized parental report questionnaire. Results showed that infant looking times varied as a function of the interaction between infants' existing fine motor skill and their experimentally-manipulated access to motor representations of the action (p = 0.017). The better an infant's fine motor skills, the greater the reduction in their looking to the object congruent with the actor's grip type under the motor interference induced by hand constraint. This effect was particularly pronounced during the precision grip trials (p = 0.032). These findings advance our understanding of the role that infants' self-experience plays in the processing of the manual actions of others. More generally, such results inform theories about the functional significance of action perception-production links in early human development.
Infants' emerging sense of agency is thought to be supported by caregivers' contingent responsiveness. However, it remains unclear which types of responses are most relevant to this process. Here, we examined the role of contingent vocal imitation, defined as the prompt repetition of an infant's vocalization by an interaction partner. To tease apart the contribution of contingent vocal imitation from other elements of social interactions, we developed a novel vocal contingency paradigm. First, we investigated whether 5- to 6-month-old infants could rapidly learn the contingency between their own vocalizing and a novel imitative response. Then, we examined whether infants tested this newly learned contingency when it was suddenly discontinued. Novel audio-visual imitative responses were delivered and manipulated by an artificial agent. Infants' vocalizations were recorded while they experienced the novel contingency (connect phase) and its discontinuation (disconnect phase). Time-course analyses indicated a significant linear increase in vocalization frequency over time in the connect phase, supporting the hypothesis that contingent vocal imitation enables rapid vocal contingency learning. Descriptively, data suggested a quadratic trend consistent with a vocal extinction burst during the disconnect phase. However, this trend did not reach statistical significance. Therefore, there was only partial support for the role of contingent vocal imitation in the emerging sense of agency (i.e., young infants quickly learned this contingency, but there was no evidence that they tested it upon discontinuation). Overall, our paradigm provided proof of concept that vocal contingency learning can be studied in the absence of a human interaction partner.
In everyday perception, expected sounds are predicted by the movement of dynamic objects. Here, we asked if four-to five-month-old infants' understanding of physical events allows them to use motion to predict the timing of collision sounds. We investigated whether infant looking time differed when viewing collision events that resulted in amodal visual or multimodal audio-visual changes. In a moderated, online study, we showed two groups of infants a moving 2-D ball and collision events. In one group, we presented infants with alternating trials from two conditions that varied in the temporal congruence of the ball's motion and collision sounds: one in which sound occurred simultaneously upon collision between the ball and a barrier (audio-visual; AV synchronous), and one where sound came slightly before collision (AV asynchronous). Another group of infants viewed the ball changing color upon collision (visual color change; VCC synchronous), and one in which the color changed slightly before collision (VCC asynchronous). Offline behavioral coding of recorded looking time demonstrated that infants looked longer toward AV asynchronous trials than to AV synchronous ones. This pattern was not seen in the group of infants who viewed color changing collisions. We also observed that infants looked longer toward AV asynchronous trials compared to VCC asynchronous trials. These data demonstrate that young infants have expectations regarding the temporal alignment of collisions and sound, which may provide a foundation for physical inference and learning in natural sensory environments.
In-person co-play between infants and adults develops rapidly during infancy, but little research has examined how families play together over video chat. Research demonstrates that video chat may support family connections, especially with grandparents and other family members separated by physical location. However, video chat interactions also place significant socio-cognitive demands on infants that may impact the frequency and variety of family play. The present study examines predictors of intergenerational virtual play compared to in-person play. We conducted an OSF pre-registered secondary analysis of data from a longitudinal study of 47 infant-parent-grandparent triads who recorded up to three naturalistic Zoom video chats and a session when they met in person. All instances of attempted infant-grandparent play were coded for playful activity type (e.g., dancing, hide & seek), duration, and whether the infant was successfully engaged in play (e.g., responded by smiling, vocalizing or imitating). Descriptive analyses revealed variability in play between families and across sessions. To capture the variety of ways in which grandparents, parents and infants played together, we fit growth models to predict the frequency of play bouts, the number of different types of playful activities observed (play repertoire), the proportion of time engaged in play, the proportion of play bouts for which infants were positively engaged, and the proportion of play bouts initiated by infants during video chat sessions. Across analyses, age was the strongest predictor of infant play on video chat. We then compared video chat play to play during the in-person session and found that play repertoire was significantly greater on video chat than in person. This study highlights the potential of digital tools to enhance intergenerational family relationships and social interactions through play. Video chat may serve as a high-quality supplemental activity for separated families.
Infants manually contact objects differently depending on their body position and the physical properties of objects. Previous studies have examined these factors separately, in structured laboratory settings, and laid the foundation for the investigation of the interaction of these elements. The current study revisits ideas from structured research in less controlled conditions by investigating how body position and the type of object shape manual contact with objects during free-flowing play. Nine-month-old infants (N = 80) participated in a semi-structured dyadic play session with their caregiver, interacting with four objects of two different kinds - two small and graspable objects; and two larger and stationary objects requiring specific actions to elicit an outcome (e.g., button pressing to make balls spin). The dyad was not constrained in terms of positioning, location on the floor, or movement around the room. We examined how the duration and frequency of infants' manual contact with objects varied based on the real-time interaction between object type and body position. The results indicate that infants contacted objects more frequently while sitting independently compared to other positions. Stationary objects were contacted more frequently but for shorter durations than graspable objects, regardless of the body position. Infants contacted graspable objects longer while sitting independently (compared to other positions), however, stationary objects were contacted with similar durations for all body positions. We found that durations of object contact depend on the interaction between object type and body position, which is more complex than what could be predicted by studies that examined these factors in isolation. These results highlight the need to study multiple interacting elements in less controlled settings.
Motor theories of action prediction propose that our neural motor system combines prior knowledge about action outcomes with current sensory input to predict other people's behavior. This knowledge can be acquired through observational experience, more specifically statistical learning. Recently, it has been shown that infants can detect in a stream of actions two actions that follow each other deterministically and that their motor system uses this knowledge to predict upcoming actions. However, real-life actions are more complex: actions rarely follow one another with 100% probability, certain actions are more likely to follow one another than others. Here, we examined whether infants can learn the statistical structure of action sequences through observation and whether the activity of their motor system reflects the statistical likelihood of upcoming actions. We trained 18-month-old infants at home with videos of action sequences featuring different transitional probabilities. At test, motor activity was measured using EEG during identical time windows that linked actions with four probability levels. While the planned analysis did not reveal a significant effect of probability, an exploratory analysis revealed that infants' motor activity over the left-central hemisphere showed a linear relationship with transitional probability of action pairs specifically in the beginning of the experiment, when infants were not fatigued, yet. Predictive motor activity was strongest when the probability was highest and weakest when no prediction was involved. These results suggest that infants' motor system is sensitive to the statistical likelihood of upcoming actions and underline the important role of statistical learning for infants' developing action understanding.
Despite decades of research, we still know less than we would like about the association between joint attention (JA) and language acquisition. One reason for this is that we still have not agreed how to define, operationalize, and measure joint attention. The goal of this study is to examine the impact of applying two different joint attention operationalization schemes-reflecting distinct theoretical perspectives-to the same dataset of video-recordings of semi-naturalistic toy-play interactions between 12-month-old children and their caregivers (N = 39). We identified joint attention around relevant naming events to determine how these choices affect interpretations of the role of joint attention in vocabulary acquisition. We compared a gaze-based coding scheme, consistent with associative accounts of joint attention, with a socially coordinated joint attention coding scheme, based on social-pragmatic theories that require, in addition to gaze overlap, evidence of shared awareness. We then extracted two measures from each scheme: average joint attention event duration and the temporal overlap between joint attention events and naming events (JA overlap). We found that while measures of joint attention were predictive of later expressive vocabulary above and beyond language-based measures in both coding schemes, model comparison based on AIC/BIC indicated that joint attention defined as coordinated JA was preferred over joint attention defined as gaze overlap. Furthermore, the best fitting model predicting later vocabulary favored predictors based on the coordinated JA scheme. Our results suggest that a social operationalization of joint attention leads to better predictors of later vocabulary size than a gaze-based operationalization of joint attention. In addition, the current study emphasizes the critical role of methodological choices in understanding how and why joint attention is associated with vocabulary size.
Maternal responsiveness to infant bids for attention predicts a variety of child outcomes including language, social-emotional, and cognitive functioning. Recently, a study demonstrated that greater maternal redirection (but not acceptance) of infant bids for attention predicted lower distractibility and, in turn, better receptive language outcomes in infants. To learn more about the potential basis for these relations, the current study took an in-depth look at differences in mother-infant dyadic behaviors as a function of whether mothers responded to infant bids for attention by redirecting versus accepting bids. We examined differences in infant gaze, mother-infant dyadic gaze, maternal multimodality (combining gaze, touch, and vocalizing), and maternal response speed. When infants (N = 67) were 12 months of age, we coded mother-infant interactions for maternal responses (accepted, redirected, ignored) to infant bids for attention. Maternal responses were further coded for multimodal behaviors (unimodal, bimodal, and trimodal) and speed of responding. The focus of infant gaze and maternal gaze were also coded (toy, partner, other). Results indicate that mothers engaged in more attentionally salient behaviors (e.g., more multimodal behaviors) when redirecting than accepting infant bids for attention, and that infants responded to those redirections with more joint attention and more looking to toys. The current study builds upon prior work and illustrates a potential process through which maternal redirection of infant bids for attention may facilitate attention control and language.
Functional magnetic resonance imaging (fMRI) in awake infants has the potential to reveal how the early developing brain gives rise to cognition and behavior. However, awake infant fMRI poses significant methodological challenges that have hampered wider adoption. The present work takes stock after the collection of a substantial amount of awake infant fMRI data across multiple studies from two labs, at Yale University and Massachusetts Institute of Technology (MIT). These data were leveraged to glean insights on participant recruitment, experimental design, and data acquisition that could be useful to consider for future studies. Across 766 fMRI sessions with awake infants aged 1-36 months, the authors explored the factors that influenced how much usable data were obtained per session. The age of an infant predicted whether they would successfully enter the scanner (younger more likely) and, if they did enter, the number of minutes of functional data collected (linear, younger more) and retained after preprocessing with lab-specific protocols or harmonized motion exclusion thresholds (quadratic, 12-24 months more than younger and older). The amount of functional data retained was also influenced by assigned sex (female more), experimental paradigm (movies better than blocks and events), and stimulus content (social better than abstract). There were many differences in the research approach between labs making head-to-head comparisons difficult, but Yale was more likely to get infants into the scanner, MIT collected more data from infants who entered, and the amount of data retained after preprocessing did not differ statistically between labs (9 min). In addition, the authors assessed the value of attempting to collect multiple experiments per session, an approach that yielded more than one usable experiment averaging across all sessions. Although any given scan is unpredictable, these findings support the feasibility of awake infant fMRI and suggest practices to optimize future research.
Social odor plays an important role for various facets of early development, including communication and social processing. Previous research focusing on maternal odor has shown that smelling the mother can influence face processing in general as well as emotion processing more specifically. However, it is unclear to what extent these effects are specific to maternal odor or can also be found for other familiar social odors. To address this question, we investigated the impact of the father's odor on emotional face processing in 7-month-old infants (age at appointment 1: 209 ± 6 days [mean ± SD], range: 199-225 days; age at appointment 2: 217 ± 6 days, range: 206-231 days; gender: 15 girls and 15 boys). We recorded the infant's EEG response to female and male happy and fearful faces while infants were exposed to either their father's odor or the odor of a different infant's father. Analysis of the frontocentral Nc amplitude revealed an enhanced response to fearful compared to happy male faces only when infants smelled their own father but not when they smelled an unfamiliar father. In contrast, emotion processing at the occipital N290 was not affected by the presence of paternal odor, suggesting an impact of social odor on attention allocation rather than structural face processing. Interestingly, all effects were specific to male faces, pointing to a gender-specific impact of social odor. Our findings therefore provide first evidence for an influence of the father's odor on face processing, specifically male faces, in infancy.
Values help shape behavior and influence how individuals assess themselves and others. Previous research on the relation between values and parenting has largely overlooked the impact of values on parenting during infancy. This study is the first to link parents' value systems to contexts meaningful to parents of infants-sleep and parent-child interactions. We explored the value systems underlying individual differences in parents' cognitions about their infants' sleep, including whether there were gender differences in parents' values. We examined whether those values directly related to their own parenting behaviors and interactions with their infants, and whether those values subsequently related to the quality of their infants' sleep. 1685 parents of infants (3-18 months) participated in an online survey on values and parenting-related choices and beliefs. Families used Nanit, a video baby monitoring system that uses computer vision technology to calculate nightly summary sleep characteristics (e.g., quality of night sleep, parent visits, night wakings). Value profiles depended on parent gender and were associated with cognitions about infant sleep and with parents' interactions with their infants, but were not associated with the quality of infants' sleep. These findings have implications for anticipating factors that could be stressful around the transition to parenthood and for interventions targeting parents' mental health and infants' sleep health.
Positioning-the body's physical configuration and relations to supports and restraints-is a fundamental aspect of infants' everyday experiences. How do everyday positioning experiences (the amount of time spent in different positions during daily life) change with the acquisition of postural skills like sitting? This study investigated relations between sitting status (whether infants have achieved a sitting milestone), sitting age (amount of time before or after that milestone), and everyday positioning experience. Forty-three infants participated at 4, 5, 6, and/or 7 months of chronological age. Everyday experience was measured using Ecological Momentary Assessment: Caregivers reported infants' current position repeatedly throughout their daily activities. The best predictors of everyday sitting experience (proportion of responses in which the infant was in an unrestrained sitting position) were chronological age and overall sitting age, calculated from the first day infants sat using hands for support; hands-free sitting age, calculated from the first day infants sat without hands, did not uniquely contribute. Sitting experience supplanted supine experience, which decreased with overall sitting age; the effect of overall sitting age on prone experience varied with chronological age. Time restrained by an adult decreased only with chronological age, and time restrained by a device was not related to chronological or sitting age. Results suggest that the continuous development of sitting skill changes the positioning composition of infants' everyday unrestrained floor time.
Parents use digital media to manage children's emotions-known as media emotion regulation. While research has focused on toddlers/preschoolers, media emotion regulation may begin in early infancy, potentially influencing media habits and socio-emotional development. Guided by the DREAMER framework, this longitudinal study examined media emotion regulation among 163 mother-infant dyads when infants were 2, 3, 4, and 5 months old. We also examined maternal, family, and infant characteristics associated with media emotion regulation (e.g., maternal depression, smartphone use, infant stressful behavior) and potential changes in infant socio-emotional outcomes (e.g., infant clarity of cues, responsiveness to mother). Data sources included monthly surveys, ecological momentary assessment (EMA) surveys, passive sensing of maternal smartphone use, and feeding observations at 2 and 5 months. Results revealed the prevalence of media emotion regulation increased from 12% at 2 months to 23% at 5 months. At 2 months, media emotion regulation was associated with greater maternal emotional dysregulation and negative perceptions of infant behavior. By 4 or 5 months, smartphone use and sensitivity began to be associated with media emotion regulation. These and other results suggest media emotion regulation may stem from maternal emotional dysregulation and stress during the early months but may become habitual over time.
While early life sets the stage for later learning, comparatively less is known about newborns' cognition than that of older infants. A striking example is the lack of consensus regarding the extent to which newborns spontaneously mimic gestures, and whether such behavior drives bonding and learning. Despite the theoretical importance of these questions, practical challenges limit researchers' ability to engage newborns in behavioral research. Webcam-based, asynchronous online studies have expanded developmental science's capacity to reach older infants. However, such scalable and replicable methods have yet to be deployed with younger infants. Taking a commonly-used neonatal mimicry paradigm as a test case, we assessed the feasibility of leveraging an open-source online platform (Children Helping Science) for asynchronous research with 0-6-week-olds and their caregivers. Caregivers modeled face movements to their 4-45 days-old infants (N = 29, N = 17 included) while webcams filmed their infants' responses; 13 dyads participated more than once (72 included test videos). Preliminary evidence suggested that infants do not mimic caregivers' tongue protrusions (Bayes Factor ∼ ⅓). Data on the mimicry of caregivers' mouth openings was inconclusive (⅓ < BF < 3). Additional analyses identified a target sample size for future studies. Finally, we asked whether caregivers perceived their newborns' behavior as imitative. Caregivers' perceptions of mimicry reflected infants' behaviors but did not align with an often-used metric of mimicry ("imitators"). These results demonstrate the feasibility of asynchronous online behavioral studies with newborns and provide a foundation for future research on neonatal mimicry of caregivers.
During early vocabulary growth, infants use single words to express complete ideas. Requests ("milk") and protests ("no!") are fundamental ways that infants communicate their needs. However, understanding what an infant wants from a single word can be challenging. Caregivers likely rely on infants' gestures and actions to interpret single-word utterances. How common are requests and protests during everyday activities? To what extent do infants accompany their requests and protests with gestures (e.g., points to request) and/or actions (e.g., flailing arms to protest)? Are caregivers more likely to respond to such "multimodal" requests and protests than to infants' words alone (i.e., unimodal speech)? We observed 31 toddlers (12-24 months) with their mothers during everyday interactions at home. In aggregate, infants expressed 2580 single-word utterances, with nearly half being requests (35%) or protests (8%). Most requests and protests (84%) were multimodal, occurring in the context of actions (mostly) or gestures. Unexpectedly, although infants' gestures/actions often "aligned" with their words in meaning or intent (e.g., saying "no" while pushing a toy away), infants also displayed "misaligned" gestures/actions (e.g., saying "no" to one toy while reaching for another). In particular, infants' aligned' multimodal requests and protests were more likely to elicit a response from mothers than were their words alone. Findings underscore the embodied and embedded nature of early communication in the natural home setting: Infants express their intentions by coupling words with gestures/actions, and certain types of multimodal communications are more effective than others in fulfilling their goals.
Smartphones can absorb attention and abruptly interrupt social interactions, a dynamic particularly critical in early parent-infant exchanges where infants rely on emotionally available caregivers for regulation. While previous research highlights the negative effects of parental media use on parenting and infant behavior, little is known about how maternal smartphone use affects both mothers' and infants' physiological and behavioral stress responses during early interactions. Consequently, we observed 67 mothers and their 6-month-old infants during an extended still-face paradigm including five phases in total: (1) an interaction baseline, (2) a still-face interruption, (3) a subsequent reunion, (4) a smartphone interruption, and (5) a subsequent reunion. The order of interruptions was randomized. Maternal and infant heart rates were continuously recorded via electrocardiogram. Infant protest and self-regulatory behaviors, as well as maternal co-regulatory behaviors, were coded from video recordings on a frame-by-frame basis. Infants showed significantly more protest behavior, higher cardiac arousal, and reduced parasympathetic activity during maternal smartphone use compared to baseline. During smartphone use, mothers reduced social engagement, accompanied by increased parasympathetic activity and decreased physiological arousal, which remained lower during reunions. We also found that dyadic physiological coupling emerged during still-face and smartphone disruptions, whereas dyadic behavioral coupling was observed only during the baseline interaction. These findings highlight the disruptive effects of maternal smartphone use and raise important questions about the potential cumulative effects of repeated smartphone interruptions on early socioemotional development.
Turn-taking, the coordinated exchange of communicative signals between infants and caregivers, is vital for child communicative development. While it is considered a human universal, most research has focused on mother-infant dyads. Given fathers' increasing caregiving involvement, understanding their contribution to early communication is essential. Thus, we have examined early infant-father turn-taking and the role of fathers' mentalizing abilities, which may support turn prediction, and paternal involvement, as it may shape the frequency and quality of exchanges. We observed 39 father-infant dyads in natural interactions at 7 weeks and 6 months postpartum. Vocalizations were micro-coded and turn-taking was defined as a vocal response by one partner within 3000 ms of the other's vocalization. Mentalizing was measured via the Reflective Functioning Scale of the Parent Development Interview, while involvement was indexed by weeks of paternity leave. Results showed little change in turn-taking over time, except for a slight decline in infant turns and increase in paternal overlaps. Mixed effect models revealed significant between-dyad variability; higher mentalizing was associated with fewer paternal overlaps, and greater involvement was linked to shorter overlap durations. Findings suggest that infants are active turn-takers from early on and paternal mentalizing may support attuned coordination. Despite a relatively homogenous sample, results underscore fathers' importance in early communicative development.
Infants are growing up in a complicated digital world, where media within the household is used to meet varying needs of the family. This paper is a version of the Presidential Address I gave in 2024 to the International Congress on Infant Studies in Glasgow. The address focused on convergence, defined as the replication of core findings across multiple methodological approaches, using examples drawn from family media ecology. The CAFE consortium is provided as an illustration of a global collaboration which created more precise measures of family media ecology and measured more diverse populations. The Dynamic Relational Ecological Approach to Media Effects Researcher (DREAMER) framework shaped the discussion from the role of individual child factors to broader structural factors. Converging findings on infant cognitive constraints on learning from media via the transfer deficit were discussed. Then both amelioration of the transfer deficit via joint engagement and exacerbation of negative outcomes due to technoference demonstrated the dynamic and relational nature of family media ecology. Structural factors, such as the COVID pandemic, drastically changed family media ecology globally. For some digital inequity led to underconnectivity and poorer outcomes and for others digital connection via videochat supported infant outcomes. Taken together the review concluded that multiple converging evidence-based findings are needed to tackle complex problems like growing up the digital age.
The literature on alternative approaches to complementary feeding, especially Baby-Led Weaning (a complementary feeding approach in which infants participate in family meals and eat finger food independently), has gradually increased in recent years. The present study aims to investigate whether there is a relation between the complementary feeding approach chosen by parents (Baby-Led Weaning or Parent-Led Weaning, in which infants are fed puréed food on a spoon) and maternal communicative functions produced during a typical meal. We analyzed the transcripts of mother-infant interactions occurring during mealtimes of 136 12-month-old typically developing infants, by means of a validated coding scheme that allows to identify five different communicative functions (Tutorial, Didactic, Conversational, Control and Asynchronous). The results highlighted a slightly different pattern of communicative style depending on the feeding method adopted by the parents (BLW vs. PLW). In particular, mothers of infants exposed to the PLW approach used the Tutorial function more often than mothers of infants exposed to the BLW method. The two groups did not differ in their use of the other functions. The implications for the promotion of healthy eating behaviors within family interactive contexts are discussed.
Infants' early pointing gestures predict their language development. One hypothesized mechanism for this relation is that pointing elicits caregivers' responses that facilitate word learning. This contingent-response hypothesis presupposes that adults can accurately interpret the communicative intent underlying infants' points, yet this has not been directly tested. Across three experiments, we examined whether adults can reliably distinguish among five pointing intent categories established in prior research, namely requestive, expressive declarative, spontaneous informative declarative, elicited informative declarative, and interrogative. In Experiment 1, 58 students interpreted infant pointing gestures in 28 video clips, identifying the most prototypical exemplars of each intent. In Experiments 2 and 3, 76 students, 53 U.S. parents, and 38 German parents rated their confidence in each intent for these 5 prototypical clips and reported how they would respond. Across all samples, participants assigned significantly higher confidence to the target intent than to alternatives and reported intent-differentiated responses. We found few differences between students and parents or between American and German parents, suggesting that interpretation of prototypical pointing gestures is not strongly dependent on child-rearing experience or cultural background, though comparisons were limited to two Western societies. These findings establish a key precondition for the contingent-response hypothesis: adults possess the interpretive capacity to provide intent-appropriate input in response to infant pointing.