Comparing Automatic and Manual Measures of Parent-Infant Conversational Turns: A Word of Caution

Conversation Initiation in Families With a Toddler Who Is Deaf or Hard of Hearing

PURPOSE

The purpose of this work is to describe the conversation initiation rates in families of toddlers who are deaf and hard of hearing (DHH) as compared to those with typical development.

METHOD

Analysis of daylong acoustic recordings was used to describe the conversational dynamics in 78 families, comprising 51 families with a DHH toddler (23 boys, 28 girls) and 27 families with a typically developing (TD) toddler (16 boys, 11 girls). Number of conversational initiations was the primary variable of interest to describe conversational dynamics within families.

RESULTS

Results of this study suggest that toddlers' conversation initiation rate does not differ by the sex or the hearing status of the child; however, mothers initiated conversations at a higher rate than fathers in both the DHH and TD groups.

CONCLUSIONS

Exploring conversation initiation provides a window into the broader development of conversational dynamics that may influence the course of language development in children, especially those with or at risk for a communication disorder. Results indicate that there was no difference in conversation initiation rate between families with DHH toddlers and families of TD toddlers, suggesting that this aspect of conversational dynamics is not influenced by pediatric hearing loss.

Validation of the Language ENvironment Analysis in Swedish Children

PURPOSE

The Language ENvironment Analysis (LENA) is a technological tool designed for comprehensive recordings and automated analysis of young children's daily language and auditory environments. LENA recordings play a crucial role in both clinical interventions and research, offering insights into the amount of spoken language children are exposed to in their homes, including adult word count (AWC) and child vocalization count (CVC). Although LENA was initially developed for American English, it has been validated in various other languages. This study aimed to evaluate the reliability of LENA in a Swedish context by comparing its automatic estimates with human transcriptions.

METHOD

Thirty-six children aged 11-29 months participated in the validation study. A total of 540 min (9 hr) of recordings were transcribed by one experienced speech-language pathologist and two special educators. Interrater agreement over 150 min was notably higher for CVC (intraclass correlation coefficient [ICC] = .97, 95% confidence interval [CI] [.91, .99], r = .96, p < .001) compared to AWC, which yielded an ICC of .82 (95% CI [.15, .96], r = .80, p = .006).

RESULTS

Both estimated CVC and AWC (n = 36) were significantly correlated with human transcriptions (r = .79 and .82, respectively; p < .001).

CONCLUSIONS

The findings align with prior validation studies, indicating that LENA is suitable for use in a Swedish context, particularly for families with children aged 11-29 months. Nonetheless, additional validation studies are necessary, particularly focusing on younger infants, to enhance our understanding of the tool's reliability in preverbal children and their caregivers.

Early developmental changes in infants' vocal responses in interactions with caregivers

OBJECTIVES

The study aimed to explore the developmental trajectory of infants' vocal responses and the temporal characteristics of vocal interactions between infants and caregivers in natural home environments, focusing specifically on Korean infants aged 3, 6, 9, and 12 months.

METHODS

One-day home recordings were collected using a LENA recorder at ages 3, 6, 9, and 12 months for each infant. In-depth analyses of the LENA recordings were conducted on 20 5-minute segments that showed the highest conversational turn counts, as determined by the LENA automated analysis. The temporal characteristics of infant vocalizations during interactions with caregivers were examined through infant vocal response, vocal response latency, and overlapping vocalizations.

RESULTS

The results indicated that the proportion of infant vocal responses following adult speech differed across age groups. Specifically, the highest proportion was observed at 3 months, with a noticeable decrease at 6 and 9 months, and a slight increase at 12 months. Infant vocal response latency increased with age, indicating longer response delays as infants got older. The proportion of overlapping vocalizations was consistent among 3, 6, and 9-month-olds but decreased significantly at 12 months.

CONCLUSION

These findings highlight distinct changes in infant vocal interactions during the first year of life. Although the analysis was cross-sectional, the observed patterns suggest developmental changes in the timing and structure of vocal response as infants age. This study indicates that infants adapt their vocal interactions in response to caregivers' speech, which may reflect a gradual learning of conversational coordination.

The everyday speech environments of preschoolers with and without cochlear implants

Children who receive cochlear implants develop spoken language on a protracted timescale. The home environment facilitates speech-language development, yet it is relatively unknown how the environment differs between children with cochlear implants and typical hearing. We matched eighteen preschoolers with implants (31-65 months) to two groups of children with typical hearing: by chronological age and hearing age. Each child completed a long-form, naturalistic audio recording of their home environment (appx. 16 hours/child; >730 hours of observation) to measure adult speech input, child vocal productivity, and caregiver-child interaction. Results showed that children with cochlear implants and typical hearing were exposed to and engaged in similar amounts of spoken language with caregivers. However, the home environment did not reflect developmental stages as closely for children with implants, or predict their speech outcomes as strongly. Home-based speech-language interventions should focus on the unique input-outcome relationships for this group of children with hearing loss.

Shaping linguistic input in parent-infant interactions: The influence of the Infant's temperament

Parent-infant interactions highlight the role of parental input, considering both the quality, infant-directed speech, and quantity of interactions, adult words and communicative turns, in these interactions. However, communication is bidirectional, yet little is known about the infant's role in these interactions. This study (n = 35 4-month-old infants) explores how infant-directed speech, the number of adult words and turn-taking (both measured by the LENA system) are correlated with infants' temperament. Our findings reveal that, while mothers use the typical characteristics of infant-directed speech, they are not correlated with the infant's temperament. However, we observe more adult-infant turn-taking in both introverted infants (with lower Surgency scores) and infants with lower attention regulation (with lower Regulatory/Orienting scores). The number of adult words was not correlated with infants' temperament. We suggest that infants with an introverted temperament prefer quieter exchanges that may lead to more turns and that infants with lower attention regulation might create more opportunities for interactions due to their lower level of self-regulation. These findings suggest that infants' temperament is associated with how adults talk with infants (communicative turns) rather than how adults talk to infants (infant-directed speech, number of adult words). Our results underscore the infant's role in parent-infant communication.

Child-directed speech in a large sample of U.S. mothers with low income

Research on early language input and socioeconomic status typically relies on correlations in small convenience samples. Using data from Baby's First Years, this paper assesses the causal impact of monthly, unconditional cash transfers on child-directed speech and child vocalizations among a large, racially diverse sample of low-income U.S. mothers and their 1-year-olds (N = 563; 48% girls; 2019-2020). The monthly, unconditional cash transfers did not impact mothers' child-directed speech during a 10-min at-home play session (effect sizes range from -.08 to .02), though there was wide variability within this sample. Future work will assess the impact of the continued cash transfer on children's language input and development over time.

Language environment and early language production in Slovenian infants: An exploratory study using daylong recordings

Daylong recordings provide an ecologically valid option for analyzing language input, and have become a central method for studying child language development. However, the vast majority of this work has been conducted in North America. We harnessed a unique collection of daylong recordings from Slovenian infants (age: 16-30 months, N = 40, 18 girls), and focus our attention on manually annotated measures of parentese (infant-directed speech with a higher pitch, slower tempo, and exaggerated intonation), conversational turns, infant words, and word combinations. Measures from daylong recordings showed large variation, but were comparable to previous studies with North American samples. Infants heard almost twice as much speech and parentese from mothers compared to fathers, but there were no differences in language input to boys and girls. Positive associations were found between the social-interactional features of language input (parentese, turn-taking) and infants' concurrent language production. Measures of child speech from daylong recordings were positively correlated with measures obtained through the Slovenian MacArthur-Bates Communicative Development Inventory. These results support the notion that the social-interactional features of parental language input are the foundation of infants' language skills, even in an environment where infants spend much of their waking hours in childcare settings, as they do in Slovenia.

Comparison of speech and music input in North American infants' home environment over the first 2 years of life

Infants are immersed in a world of sounds from the moment their auditory system becomes functional, and experience with the auditory world shapes how their brain processes sounds in their environment. Across cultures, speech and music are two dominant auditory signals in infants' daily lives. Decades of research have repeatedly shown that both quantity and quality of speech input play critical roles in infant language development. Less is known about the music input infants receive in their environment. This study is the first to compare music input to speech input across infancy by analyzing a longitudinal dataset of daylong audio recordings collected in English-learning infants' home environments, at 6, 10, 14, 18, and 24 months of age. Using a crowdsourcing approach, 643 naïve listeners annotated 12,000 short snippets (10 s) randomly sampled from the recordings using Zooniverse, an online citizen-science platform. Results show that infants overall receive significantly more speech input than music input and the gap widens as the infants get older. At every age point, infants were exposed to more music from an electronic device than an in-person source; this pattern was reversed for speech. The percentage of input intended for infants remained the same over time for music while that percentage significantly increased for speech. We propose possible explanations for the limited music input compared to speech input observed in the present (North American) dataset and discuss future directions. We also discuss the opportunities and caveats in using a crowdsourcing approach to analyze large audio datasets. A video abstract of this article can be viewed at https://youtu.be/lFj_sEaBMN4 RESEARCH HIGHLIGHTS: This study is the first to compare music input to speech input in infants' natural home environment across infancy. We utilized a crowdsourcing approach to annotate a longitudinal dataset of daylong audio recordings collected in North American home environments. Our main results show that infants overall receive significantly more speech input than music input. This gap widens as the infants get older. Our results also showed that the music input was largely from electronic devices and not intended for the infants, a pattern opposite to speech input.

The Language ENvironment Analysis system (LENA): A validation study with Italian-learning children

This study is a validation of the LENA system for the Italian language. In Study 1, to test LENA's accuracy, seventy-two 10-minute samples extracted from daylong LENA recordings were manually transcribed for 12 children longitudinally observed at 1;0 and 2;0. We found strong correlations between LENA and human estimates in the number of Adult Word Count (AWC) and Child Vocalisations Count (CVC) and a weak correlation between LENA and human estimates in Conversational Turns Count (CTC). In Study 2, to test the concurrent validity, direct and indirect language measures were considered on a sample of 54 recordings (19 children). Correlational analyses showed that LENA's CVC and CTC were significantly related to the children's vocal production, a parent report measure of prelexical vocalizations and the vocal reactivity scores. These results confirm that the automatic analyses performed by the LENA device are reliable and powerful for studying language development in Italian-speaking infants.

Evaluating the accuracy of automated processing of child and adult language production in preschool classrooms

Young children's language and social development is influenced by the linguistic environment of their classrooms, including their interactions with teachers and peers. Measurement of the classroom linguistic environment typically relies on observational methods, often providing limited 'snapshots' of children's interactions, from which broad generalizations are made. Recent technological advances, including artificial intelligence, provide opportunities to capture children's interactions using continuous recordings representing much longer durations of time. The goal of the present study was to evaluate the accuracy of the Interaction Detection in Early Childhood Settings (IDEAS) system on 13 automated indices of language output using recordings collected from 19 children and three teachers over two weeks in an urban preschool classroom. The accuracy of language outputs processed via IDEAS were compared to ground truth via linear correlations and median absolute relative error. Findings indicate high correlations between IDEAS and ground truth data on measures of teacher and child speech, and relatively low error rates on the majority of IDEAS language output measures. Study findings indicate that IDEAS may provide a useful measurement tool for advancing knowledge about children's classroom experiences and their role in shaping development.

Daylong egocentric recordings in small- and large-scale language communities: A practical introduction

Daylong egocentric (i.e., participant-centered) recordings promise an unprecedented view into the experiences that drive early language learning, impacting both assumptions and theories about how learning happens. Thanks to recent advances in technology, collecting long-form audio, photo, and video recordings with child-worn devices is cheaper and more convenient than ever. These recording methods can be similarly deployed across small- and large-scale language communities around the world, opening up enormous possibilities for comparative research on early language development. However, building new high-quality naturalistic corpora is a massive investment of time and money. In this chapter, we provide a practical look into considerations relevant for developing and managing daylong egocentric recording projects: Is it possible to re-use existing data? How much time will manual annotation take? Can automated tools sufficiently tackle the questions at hand? We conclude by outlining two exciting directions for future naturalistic child language research.

Estimating infants' language exposure: A comparison of random and volume sampling from daylong recordings collected in a bilingual community

In North America, the characteristics of a child's language environment predict language outcomes. For example, differences in bilingual language exposure, exposure to electronic media, and exposure to child-directed speech (CDS) relate to children's language growth. Recently, these predictors have been studied through the use of daylong recordings, followed by manual annotation of audio samples selected from these recordings. Using a dataset of daylong recordings collected from bilingually raised infants in the United States as an example, we ask whether two of the most commonly used sampling methods, random sampling and sampling based on high adult speech, differ from each other with regard to estimating the frequencies of specific language behaviors. Daylong recordings from 37 Spanish-English speaking families with infants between 4 and 22 months of age were analyzed. From each child's recording, samples were extracted in two ways (at random/based on high adult speech) and then annotated for Language (Spanish/English/Mixed), CDS, Electronic Media, Social Context, Turn-Taking, and Infant Babbling. Correlation and agreement analyses were performed, in addition to paired sample t-tests, to assess how the choice of one or the other sampling method may affect the estimates. For most behaviors studied, correlation and agreement between the two sampling methods was high (Pearson r values between 0.79 and 0.99 for 16 of 17 measures; Intraclass Correlation Coefficient values between 0.78 and 0.99 for 13 of 17 measures). However, interesting between-sample differences also emerged: the degree of language mixing, the amount of CDS, and the number of conversational turns were all significantly higher when sampling was performed based on high adult speech compared to random sampling. By contrast, the presence of electronic media and one-on-one social contexts was higher when sampling was performed at random. We discuss advantages of choosing one sampling technique over the other, depending on the research question and variables at hand.

Parentese in infancy predicts 5-year language complexity and conversational turns

Parental input is considered a key predictor of language achievement during the first years of life, yet relatively few studies have assessed its effects on longer-term outcomes. We assess the effects of parental quantity of speech, use of parentese (the acoustically exaggerated, clear, and higher-pitched speech), and turn-taking in infancy, on child language at 5 years. Using a longitudinal dataset of daylong LENA recordings collected with the same group of English-speaking infants (N=44) at 6, 10, 14, 18, 24 months and then again at 5 years, we demonstrate that parents' consistent (defined as stable and high) use of parentese in infancy was a potent predictor of lexical diversity, mean length of utterance, and frequency of conversational turn-taking between children and adults at Kindergarten entry. Together, these findings highlight the potential importance of a high-quality language learning environment in infancy for success at the start of formal schooling.

The impact of a community-based music program during infancy on the quality of parent-child language interactions

The early language environment, especially high-quality, contingent parent-child language interactions, is crucial for a child's language development and later academic success. In this secondary analysis study, 89 parent-child dyads were randomly assigned to either the Music Together® (music) or play date (control) classes. Children were 9- to 15-month old at baseline, primarily white (86.7%) and female (52%). Measures of conversational turns (CTs) and parental verbal quality were coded from parent-child free play episodes at baseline, mid-intervention (month 6), and post-intervention (month 12). Results show that participants in the music group had a significantly greater increase in CT measures and quality of parent verbalization post-intervention. Music enrichment programs may be a strategy to enhance parent-child language interactions during early childhood.

A comparison of automatic and manual measures of turn-taking in monolingual and bilingual contexts

The Language ENvironment Analysis system (LENA) records children's language environment and provides an automatic estimate of adult-child conversational turn count (CTC) by automatically identifying adult and child speech in close temporal proximity. To assess the reliability of this measure, we examine correlation and agreement between LENA's CTC estimates and manual measurement of adult-child turn-taking in two corpora collected in the USA: a bilingual corpus of Spanish-English-speaking families with infants between 4 and 22 months (n = 37), and a corpus of monolingual families with English-speaking 5-year-olds (n = 56). In each corpus for each child, 100 30-second segments were extracted from daylong recordings in two ways, yielding a total of 9300 minutes of manually annotated audio. LENA's CTC estimate for the same segments was obtained through the LENA software. The two measures of CTC had low correlations for the segments from the monolingual 5-year-olds sampled in both ways, and somewhat higher correlations for the bilingual samples. LENA substantially overestimated CTC on average, relative to manual measurement, for three out of four analysis conditions, and limits of agreement were wide in all cases. Segment-level analyses demonstrated that accidental contiguity had the largest individual impact on LENA's average CTC error, affecting 12-17% of analyzed segments. Other factors significantly contributing to CTC error were speech from other children, presence of multiple adults, and presence of electronic media. These results indicate wide discrepancies between LENA's CTC estimates and manual CTCs, and call into question the comparability of LENA's CTC measure across participants, conditions, and developmental time points.

Factors of parental investment in the home language environment in peri-urban China: A mixed methods study

The home language environment is a critical point of investment in early language skills. However, few studies have quantitatively measured the home language environment of low-socioeconomic-status households in non-western settings. This mixed methods study describes the home language environment and early child language skills among households in a low-socioeconomic-status, peri-urban district of Chengdu, China, and identifies factors influencing parental investment in the home language environment. Audio recordings were collected from 81 peri-urban households with children ages 18-24 months and analysed using the Language Environment Analysis (LENATM) system. The Mandarin version of the MacArthur-Bates Communicative Development Inventory was administered to each child's primary caregiver. The quantitative results revealed large variation in home language environments and child language skills among the sample, with relatively low average scores when compared to other Chinese samples. Qualitative interviews with a subset of 31 caregivers revealed that many caregivers face constraints on their knowledge of interactive parenting, compounded, in some households, by time constraints due to work or household responsibilities. The findings indicate a need for increased sources of credible parenting information for peri-urban caregivers of young children to promote investment in the home language environment.

Parent coaching from 6 to 18 months improves child language outcomes through 30 months of age

Interventions focused on the home language environment have been shown to improve a number of child language outcomes in the first years of life. However, data on the longer-term effects of the intervention are still somewhat limited. The current study examines child vocabulary and complex speech outcomes (N = 59) during the year following completion of a parent-coaching intervention, which was previously found to increase the quantity of parent-child conversational turns and to improve child language outcomes through 18 months of age. Measures of parental language input, child speech output, and parent-child conversational turn-taking were manually coded from naturalistic home recordings (Language Environment Analysis System, LENA) at regular 4-month intervals when children were 6- to 24-months old. Child language skills were assessed using the MacArthur-Bates Communicative Development Inventory (CDI) at four time-points following the final intervention session (at 18, 24, 27, and 30 months). Vocabulary size and growth from 18 to 30 months was greater in the intervention group, even after accounting for differences in child language ability during the intervention period. The intervention group also scored higher on measures of speech length and grammatical complexity, and these effects were mediated by 18-month vocabulary. Intervention was associated with increased parent-child conversational turn-taking in home recordings at 14 months, and mediation analysis suggested that 14-month conversational turn-taking accounted for intervention-related differences in subsequent vocabulary. Together, the results suggest enduring, positive effects of parental language intervention and underscore the importance of interactive, conversational language experience during the first 2 years of life. RESEARCH HIGHLIGHTS: Parent coaching was provided as part of a home language intervention when children were 6-18 months of age. Naturalistic home language recordings showed increased parent-child conversational turn-taking in the intervention group at 14 months of age. Measures of productive vocabulary and complex speech indicated more advanced expressive language skills in the intervention group through 30 months of age, a full year after the final intervention session. Conversational turn-taking at 14 months predicted subsequent child vocabulary and accounted for differences in vocabulary size across the intervention and control groups.

Investigating Children's Interactions in Preschool Classrooms: An Overview of Research Using Automated Sensing Technologies

New technologies that combine digital sensors with automated processing algorithms are now being deployed to study preschool classrooms. This article provides an overview of these new sensing technologies, focusing on automated speaker classification, the analysis of children's and teachers' speech, and the detection and analysis of their movements over the course of the school day. Findings from recent studies utilizing these technologies are presented to illustrate the contribution of these sensing technologies to our understanding of classroom processes that predict children's language and social development. In particular, the potential to collect extended real-time data on the speech and movement of all children and teachers in a classroom provides a broader window on the variability of individual children's interactions with peers and teachers and their integration into classroom social networks. The article describes current challenges related to the use of sensing technologies in preschool settings, as well as advances that may overcome these challenges and allow for more in-depth investigations of children's early classroom experiences.

Language exposure during infancy is negatively associated with white matter microstructure in the arcuate fasciculus

Decades of research have established that the home language environment, especially quality of caregiver speech, supports language acquisition during infancy. However, the neural mechanisms behind this phenomenon remain under studied. In the current study, we examined associations between the home language environment and structural coherence of white matter tracts in 52 typically developing infants from English speaking homes in a western society. Infants participated in at least one MRI brain scan when they were 3, 6, 12, and/or 24 months old. Home language recordings were collected when infants were 9 and/or 15 months old. General linear regression models indicated that infants who heard the most adult words and participated in the most conversational turns at 9 months of age also had the lowest fractional anisotropy in the left posterior parieto-temporal arcuate fasciculus at 24 months. Similarly, infants who vocalized the most at 9 months also had the lowest fractional anisotropy in the same tract at 6 months of age. This is one of the first studies to report significant associations between caregiver speech collected in the home and white matter structural coherence in the infant brain. The results are in line with prior work showing that protracted white matter development during infancy confers a cognitive advantage.

The validity of LENA technology for assessing the linguistic environment and interactions of infants learning Hebrew and Arabic

The present study assessed LENA's suitability as a tool for monitoring future language interventions by evaluating its reliability, construct validity, and criterion validity in infants learning Hebrew and Arabic, across low and high levels of maternal education. Participants were 32 infants aged 3 to 11 months (16 in each language) and their mothers, whose socioeconomic status (SES) was determined based on their years of education (H-high or L-low ME-maternal education). The results showed (1) good reliability for the LENA's automatic count on adult word count (AWC), conversational turns (CTC), and infant vocalizations (CVC), based on the positive associations and fair to excellent agreement between the manual and automatic counts; (2) good construct validity based on significantly higher counts for HME vs. LME and positive associations between LENA's automatic vocal assessment (AVA) and developmental questionnaire (DA) and age; and (3) good concurrent criterion validity based on the positive associations between the LENA counts for CTC, CVC, AVA, and DA and the scores on the preverbal parent questionnaire (PRISE). The present study supports the use of LENA in early intervention programs for infants whose families speak Hebrew or Arabic. The LENA could be used to monitor the efficacy of these programs as well as to provide feedback to parents on the amount of language experience their infants are getting and their progress in vocal production. The results also indicate a potential utility of LENA in assessing linguistic environments and interactions in Hebrew- and Arabic-speaking infants with developmental disorders, such as hearing impairment and cerebral palsy.

Does age moderate the influence of early life language experiences? A Naturalistic home observation study

We explored if children's age moderated associations between their early life language experiences and their linguistic and cognitive skills. For 107 British children, aged 24 to 48 months, and their families, we collected 3 day-long audio-recordings of their naturalistic home environments (M = 15.06 h per day, SD = 1.87). Children's cognitive ability was assessed by parent-ratings and with a cognitive testing booklet that children completed at home. We found that the quantity, lexical diversity and vocabulary sophistication of adult speech were associated with children's linguistic and cognitive skills. However, these associations were not moderated by children's age. Our findings suggest that the influence of early life language experience is not differentiated at age 24 to 48 months, at least in the current sample.

Language Experience during Infancy Predicts White Matter Myelination at Age 2 Years

Parental input is considered a key predictor of language achievement during the first years of life, yet relatively few studies have assessed the effects of parental language input and parent-infant interactions on early brain development. We examined the relationship between measures of parent and child language, obtained from naturalistic home recordings at child ages 6, 10, 14, 18, and 24 months, and estimates of white matter myelination, derived from quantitative MRI at age 2 years (mean = 26.30 months, SD = 1.62, N = 22). Analysis of the white matter focused on dorsal pathways associated with expressive language development and long-term language ability, namely, the left arcuate fasciculus (AF) and superior longitudinal fasciculus (SLF). Frequency of parent-infant conversational turns (CT) uniquely predicted myelin density estimates in both the AF and SLF. Moreover, the effect of CT remained significant while controlling for total adult speech and child speech-related utterances, suggesting a specific role for interactive language experience, rather than simply speech exposure or production. An exploratory analysis of 18 additional tracts, including the right AF and SLF, indicated a high degree of anatomic specificity. Longitudinal analyses of parent and child language variables indicated an effect of CT as early as 6 months of age, as well as an ongoing effect over infancy. Together, these results link parent-infant conversational turns to white matter myelination at age 2 years, and suggest that early, interactive experiences with language uniquely contribute to the development of white matter associated with long-term language ability.SIGNIFICANCE STATEMENT Children's earliest experiences with language are thought to have profound and lasting developmental effects. Recent studies suggest that intervention can increase the quality of parental language input and improve children's learning outcomes. However, important questions remain about the optimal timing of intervention, and the relationship between specific aspects of language experience and brain development. We report that parent-infant turn-taking during home language interactions correlates with myelination of language related white matter pathways through age 2 years. Effects were independent of total speech exposure and infant vocalizations and evident starting at 6 months of age, suggesting that structured language interactions throughout infancy may uniquely support the ongoing development of brain systems critical to long-term language ability.

Immature Vocalizations Simplify the Speech of Tseltal Mayan and U.S. Caregivers

What is the function of immature vocalizing in early learning environments? Previous work on infants in the United States indicates that prelinguistic vocalizations elicit caregiver speech which is simplified in its linguistic structure. However, there is substantial cross-cultural variation in the extent to which children's vocalizations elicit responses from caregivers. In the current study, we ask whether children's vocalizations elicit similar changes in their immediate caregivers' speech structure across two cultural sites with differing perspectives on how to interact with infants and young children. Here, we compare Tseltal Mayan and U.S. caregivers' verbal responses to their children's vocalizations. Similar to findings from U.S. dyads, we found that children from the Tseltal community regulate the statistical structure of caregivers' speech simply by vocalizing. Following the interaction burst hypothesis, where clusters of child-adult contingent response alternations facilitate learning from limited input, we reveal a stable source of information that may facilitate language learning within ongoing interaction.

Language input in late infancy scaffolds emergent literacy skills and predicts reading related white matter development

Longitudinal studies provide the unique opportunity to test whether early language provides a scaffolding for the acquisition of the ability to read. This study tests the hypothesis that parental language input during the first 2 years of life predicts emergent literacy skills at 5 years of age, and that white matter development observed early in the 3rd year (at 26 months) may help to account for these effects. We collected naturalistic recordings of parent and child language at 6, 10, 14, 18, and 24 months using the Language ENvironment Analysis system (LENA) in a group of typically developing infants. We then examined the relationship between language measures during infancy and follow-up measures of reading related skills at age 5 years, in the same group of participants (N = 53). A subset of these children also completed diffusion and quantitative MRI scans at age 2 years (N = 20). Within this subgroup, diffusion tractography was used to identify white matter pathways that are considered critical to language and reading development, namely, the arcuate fasciculus (AF), superior and inferior longitudinal fasciculi, and inferior occipital-frontal fasciculus. Quantitative macromolecular proton fraction (MPF) mapping was used to characterize myelin density within these separately defined regions of interest. The longitudinal data were then used to test correlations between early language input and output, white matter measures at age 2 years, and pre-literacy skills at age 5 years. Parental language input, child speech output, and parent-child conversational turns correlated with pre-literacy skills, as well as myelin density estimates within the left arcuate and superior longitudinal fasciculus. Mediation analyses indicated that the left AF accounted for longitudinal relationships between infant home language measures and 5-year letter identification and letter-sound knowledge, suggesting that the left AF myelination at 2 years may serve as a mechanism by which early language experience supports emergent literacy.

Electronic media and social features of language input in bilingually-raised Latinx infants

The present study examines the language environments of bilingually-raised Latinx infants (n = 37) to characterize the relation between exposure to electronic media and infants' language input, with a specific focus on parentese, a near-universal style of infant-directed speech, distinguished by its higher pitch, slower tempo, and exaggerated intonation. Previous research shows that parentese and parent-infant turn-taking are both associated with advances in children's language learning. Here we test the hypothesis that exposure to electronic media is associated with a reduction in these two social features of language input. Using the Language Environment Analysis (LENA) technology, two daylong audio recordings were collected from each family. Exposure to electronic media was measured in three ways: 1) Through LENA's automatic estimate; 2) Through manual annotation of LENA audio recordings; and 3) Through a parental questionnaire. Language of electronic media, parental language input, and child language output were quantified through automatic and manual analyses of LENA recordings. Infants' estimated daily exposure to electronic media varied between the three methods used. There was a significant positive correlation between daily media exposure assessed via the two observational methods, but neither significantly correlated with parental report. Infants experienced electronic media in Spanish and English, and the language of electronic media correlated with the language of paternal and maternal child-directed speech. Linear regression analyses controlling for demographics (infant age, sex, socioeconomic status) demonstrated a negative association between exposure to electronic media and parentese, as well as between exposure to electronic media and turn-taking. Exposure to electronic media was also negatively associated with infants' linguistic vocalizations. The present findings suggest that exposure to electronic media negatively impacts infant vocal activity by reducing parental parentese and parent-infant turn-taking, which are known to positively impact infants' linguistic, socioemotional, and cognitive development. This analysis is an important step forward in understanding Latinx infants' electronic media ecologies and their relation to language input and language development.

Daylong Mobile Audio Recordings Reveal Multitimescale Dynamics in Infants' Vocal Productions and Auditory Experiences

The sounds of human infancy-baby babbling, adult talking, lullaby singing, and more-fluctuate over time. Infant-friendly wearable audio recorders can now capture very large quantities of these sounds throughout infants' everyday lives at home. Here, we review recent discoveries about how infants' soundscapes are organized over the course of a day based on analyses designed to detect patterns at multiple timescales. Analyses of infants' day-long audio have revealed that everyday vocalizations are clustered hierarchically in time, vocal explorations are consistent with foraging dynamics, and musical tunes are distributed such that some are much more available than others. This approach focusing on the multi-scale distributions of sounds heard and produced by infants provides new, fundamental insights on human communication development from a complex systems perspective.

The home environment and its relation to vocalizations in the first year of life

Background

Prior data has shown that the home environment impacts child development; however, there remains a paucity of research on how the home environment relates to child and adult words. Therefore, the aim of this prospective and quantitative study was to examine the relationship between the home environment and the quantity of vocalizations or words, and conversational turns produced by infants and parents at 3 and 12 months of age.

Methods

Seventy-two (56% male) full-term infants were assessed at 3 and 12 months of age. The home environment was assessed in person via interview and observation of the child's home using the Infant-Toddler Home Observation for Measurement of the Environment (IT-HOME) Inventory subscales. Vocalizations were measured using the Language Environment Analysis (LENA) device, which measures the adult word count, child vocalization count and conversational turn count. These measures were then averaged for the most voluble, or vocal hour, in the recording period.

Results

At 3 months, IT-HOME Learning Materials scores were significantly associated with a decrease in adult words. We found a statistically significant difference in LENA outcomes between 3 and 12 months when stratified by sex. Specifically, male infants had significantly fewer vocalizations at 12 months when compared to 3 months, whereas females had more vocalizations. There was also a statistically significant difference in IT-HOME Learning Materials, Organization, Responsivity, and Total scores when comparing 3- and 12-month time points.

Conclusions

These findings reveal that the home environment changes significantly over the first year of life. At 3 months, Learning Materials in the home were related to adult words, while between 3 and 12 months, several aspects of the home significantly changed. Male children had reduced vocalizations between 3 and 12 months; whereas, female children had increased vocalizations during the same time points. Future research should focus on examining these outcomes with multiple measures, time points, and patient populations.

Language and socioemotional development in early childhood: The role of conversational turns

This study examines the role of language environment (number of conversational turns) in the development of socioemotional competencies between 18 and 30 months. The language environment of 43 infants and their social-emotional competencies were measured at 18 months and again at 30 months. Multiple regressions showed a significant contribution of turns at 18 months on socioemotional competencies at 30 months, controlling for their initial levels, child vocalizations, maternal warmth, and social risk. Cross-lagged analysis revealed that the direction of the longitudinal relation between turns and emotional competencies is more likely to go from turns to socioemotional development than the other way around. Implications for theory and research are discussed.

Media exposure and language experience: Examining associations from home observations in Mexican immigrant families in the US

The current exploratory study describes exposure to digital media in young children from Mexican immigrant homes and its association with language input and output. Using multiple recordings of children's home environments, we report on the rate (i.e., percentage of total recording time), language (Spanish or English), and type (adult- or child-directed programming) of auditory media exposure in toddlers under three years of age (N = 30; M_age = 20;3 months). We also examine total adult words and adult-child conversational turns, as indicators of child language input, and the number of child language vocalizations as a measure of early language development. Findings showed that digital media comprised approximately 14 % of the child language environment that families selected to record, with wide variability observed. Children were more likely to be exposed to media in Spanish than English and adult-directed than child-directed programming. Children's general media exposure was negatively associated with the amount of children's vocalizations and conversational turns but not the quantity of adult words in the environment, suggesting that the relation between media exposure and child language development is likely not mediated by a general decrease in adult input in Mexican immigrant homes. Instead, media exposure may decrease opportunities for children to engage in conversation and practice language expression, both critical mechanisms for successful language acquisition. Selection of child-directed programming may encourage child vocalizations but is less likely to be in Spanish in these homes, which may reduce opportunities for engagement with Spanish-dominant adults. Together these findings provide a window into the nature of media exposure in children from Mexican immigrant homes and into the associations between media and language input and output. Directions for future research are discussed.