Adult responses to infant prelinguistic vocalizations are associated with infant vocabulary: A home observation study

The Predictability of Naturalistic Evaluation of All-Day Recordings for Speech and Language Development

OBJECTIVES

The study aimed to investigate the predictive potential of language environment and vocal development status measures obtained through integrated analysis of Language ENvironment Analysis (LENA) recordings during the prelinguistic stage for subsequent speech and language development in Korean-acquiring children. Specifically, this study explored whether measures from both LENA-automated analysis and human coding at 6-8 months and 12-14 months of age predict vocabulary and phonological development at 18-20 months.

METHOD

One-day home recordings from 20 children were collected using a LENA recorder at 6-8 months, 12-14 months, and 18-20 months. Both LENA-automated measures and measures from human coding were obtained from recordings at 6-8 months and 12-14 months. The number of different words, consonant inventory, and utterance structure inventory were identified from recordings of 18-20 months. Correlation and multiple regression analyses were performed to investigate whether measures related to early language environment and child vocalization at 6-8 months and 12-14 months were predictive of vocabulary and phonological measures at 18-20 months.

RESULTS

The results showed that the two main LENA-automated measures, conversational turn count (CTC) and child vocalization count, were positively correlated with all vocabulary and phonological measures at 18-20 months. Multiple regression analysis revealed that CTC during the prelinguistic stages was the most significant predictor of a number of different words, consonant inventory, and utterance structure inventory at 18-20 months. Also, adult word count in LENA-automated measures, child-directed speech ratio, and canonical babbling ratio measured by human coding significantly predicted some vocabulary and phonological measures at 18-20 months.

CONCLUSION

This study highlights the multifaceted nature of language acquisition and collectively emphasizes the value of considering both quantitative and qualitative aspects of language input to understand early language development in children.

Caregiver encouragement to act on objects is related with crawling infants' receptive language

The progression from crawling to walking in infancy is associated with changes in infant language development. One possible explanation for such change is the infant's language environment. Prior research indicates that caregivers use more action directives with walking infants compared to crawling infants, but the relations of such parental speech with infant vocabulary is unknown. Here, we present findings from day-long home audio recordings (Study 1) and laboratory observations (Study 2) of same-aged crawling and walking infants to explore how caregiver language, specifically action directives, were associated with parent reported infant vocabulary size. Findings in both studies indicated that caregiver action directives were associated with crawling, but not walking infants' receptive vocabulary sizes. Specifically, action directives about objects occurring when the infant and caregiver were not jointly engaged were associated with higher receptive vocabulary scores for crawling infants, but no such pattern was found for walking infants. The replication of results in distinct samples with different research methodologies strengthens the findings. Taken together, these studies demonstrate that caregiver social engagement specific to infant motoric development is related with infant language learning.

Building language learning: Relations between infant attention and social contingency in the first year of life

In Western societies, social contingency, or prompt and meaningful back-and-forth exchanges between infant and caregiver, is a powerful feature of the early language environment. Research suggests that infants with better attentional skills engage in more social contingency during interactions with adults and, in turn, social contingency supports infant attention. This reciprocity is theorized to build infant language skills as the adult capitalizes on and extends the infant's attention during socially contingent interactions. Using data from 104 infants and caregivers, this paper tests reciprocal relations between infant attention and social contingency at 6- and 12-months and the implications for infant vocabulary at 18-months. Infant attentional skills to social (women speaking) and nonsocial (objects dropping) events were assessed, and social contingency was examined during an 8-minute toy play interaction with a caregiver. Child receptive and expressive vocabulary was measured by caregiver-report. Both social and nonsocial attentional skills related to engagement in social contingency during caregiver-infant interaction, though only models that included social attention and social contingency predicted vocabulary. These findings provide empirical evidence for the proposed reciprocal relations between infant attention and social contingency as well as how they relate to later language.

Associations between urbanization and the home language environment: Evidence from a LENA study in rural and peri-urban China

In low- and middle-income countries, urbanization has spurred the expansion of peri-urban communities, or urban communities of formerly rural residents with low socioeconomic status. The growth of these communities offers researchers an opportunity to measure the associations between the level of urbanization and the home language environment (HLE) among otherwise similar populations. Data were collected in 2019 using Language Environment Analysis observational assessment technology from 158 peri-urban and rural households with Han Chinese children (92 males, 66 females) aged 18-24 months in China. Peri-urban children scored lower than rural children in measures of the HLE and language development. In both samples, child age, gender, maternal employment, and sibling number were positively correlated with the HLE, which was in turn correlated with language development.

Prelinguistic communication complexity predicts expressive language in initial minimally verbal autistic children

BACKGROUND

Prelinguistic communication complexity refers to the use of different communication forms such as eye gaze, gestures and vocalisations and the degree to which these forms are coordinated and how directed to a communication partner. To date, little is known about the relationship between prelinguistic communication complexity and expressive language in minimally verbal autistic children.

AIMS

To test the hypothesis that prelinguistic communication complexity predicts expressive language 12 months later in autistic children and explore whether there are any differences in specific prelinguistic intentional communicative behaviours that are related to later expressive language levels.

METHODS & PROCEDURES

This longitudinal study examined 37 minimally verbal autistic children (29-71 months old). The Communication Complexity Scale (CCS) was used to measure participants' prelinguistic communication behaviours, which were extracted from a semi-structured play interaction at Time 1. The Chinese Communicative Development Inventory (CCDI) was used to examine participants' expressive language at Time 1 and Time 2 (12 months later). According to Time 2 vocabulary size, participants were divided into two groups: Low CCDI, between 0 and 62 words, and High CCDI, more than 100 words. Linear regression was used to examine the relationship between early prelinguistic communication complexity and later expressive language. Binary logistic regression was used to determine which of the early communication behaviours were uniquely significantly related to later expressive language levels.

OUTCOMES & RESULTS

There was a significant positive relationship between prelinguistic communication complexity and expressive language 12 months later, even after controlling for age and concurrent language. Findings revealed a group difference in the frequency of gesture and vocalisation combinations between the Low and High CCDI groups at Time 1. Gesture-vocalisation combinations also predicted better expressive language levels at Time 2.

CONCLUSIONS & IMPLICATIONS

Our findings suggest that it may be beneficial to incorporate different complex communication behaviours into prelinguistic intervention targets for minimally verbal autistic children. The CCS hierarchies can be used as a reference for the intervention goals of minimally verbal autistic children. These findings highlight the importance of targeting gesture and vocalisation combinations when autistic children transition from single prelinguistic communication behaviours to multimodal behaviours.

WHAT THIS PAPER ADDS

What is already known on this subject Children use eye gaze, gestures and vocalisations to communicate with others before they learn spoken language. There is strong evidence suggest that the frequency of prelinguistic communication predicts later linguistic achievements in autistic children. However, less is known about whether prelinguistic communication complexity also predicts later language and which specific behaviours are most predictive of language outcomes. What this study adds Minimally verbal autistic children who exhibit more complex prelinguistic communication behaviours have better expressive language 12 months later. Gestures combined with vocalisations predict better expressive language in minimally verbal autistic children. What are the clinical implications of this work? When identifying intervention targets for minimally verbal autistic children, the clinicians may reference the prelinguistic communication behaviours from the CCS. The gesture and vocalisation combinations are the key behaviours when targets transit from single form to two-form behaviours.

Mother-child and father-child "serve and return" interactions at 9 months: Associations with children's language skills at 18 and 24 months

Infants learn language through the back-and-forth interactions with their parents where they "serve" by uttering sounds, gesturing, or looking and parents "return" in prompt (i.e., close in time) and meaningful (i.e., semantically relevant to the object of interest) ways. In a sample of 9-month-old infants (n = 148) and their mothers and fathers (n = 296 parents) from ethnically and socioeconomically diverse backgrounds, we examined the associations between "serve and return" (SR) parent-child interactions and children's language skills at 18 and 24 months. We also examined the moderation effects between maternal and paternal SR interactions on language outcomes. SR interactions were transcribed and coded from videotaped parent-child toy play activities during home visits. We report three findings. First, mothers who provided more meaningful responses to their child's serves at 9 months had children with higher expressive language scores at 18 months. Second, fathers' prompt responses (i.e., within 3 s) at 9 months were associated with higher receptive language scores at 18 months, but their meaningful responses were negatively associated with receptive language scores at 24 months. Third, the negative association between fathers' meaningful responses and children's receptive language scores was reduced (compensated) when mothers' meaningful responses were high. Findings show that infants in ethnically and socioeconomically diverse families engage in frequent SR interactions with both mothers and fathers, who make unique contributions to infants' language development. We discuss implications for programs and policies that aim to promote early language development and reduce gaps in school readiness.

Mixed-Language Input and Infant Volubility: Friend or Foe?

Language mixing is a common feature of many bilingually-raised children's input. Yet how it is related to their language development remains an open question. The current study investigated mixed-language input indexed by observed (30-second segment) counts and proportions in day-long recordings as well as parent-reported scores, in relation to infant vocal activeness (i.e., volubility) when infants were 10 and 18 months old. Results suggested infants who received a higher score or proportion of mixed input in one-on-one social contexts were less voluble. However, within contexts involving language mixing, infants who heard more words were also the ones who produced more vocalizations. These divergent associations between mixed input and infant vocal development point for a need to better understand the causal factors that drive these associations.

Parental verbal responsiveness to infant vocalizations from 9 to 14 months of age

Parental communication styles and language usage may undergo changes during the course of child development, exhibiting variations across language backgrounds and cultures. This study aimed to explore how infant-parent interactions within Korean-speaking environments evolve over time through meticulous coding of day-long home audio recordings. The study examined whether the ratio and types of parental verbal responses vary based on infants' age and vocalization types. A total of 16 infants and their parents participated in all-day home recordings using the Language Environment Analysis (LENA) system. The recordings were conducted in two rounds per family when the infants were aged 9-11 months and 12-14 months, with a three-month gap between each round. The frequency and types of infant vocalizations were analyzed and the contingency and types of parental verbal responsiveness were determined based on semantic and phonetic connection, as well as temporal appropriateness. The results showed that parents did not verbally respond to approximately 50 % of the infant vocalizations in the natural home environment. However, parents' lack of verbal responses decreased significantly, and their contingent responses increased significantly with infant age. Parents were also not selectively responsive to infants' canonical vocalizations over non-canonical vocalizations. Nevertheless, parents demonstrated a higher frequency of responses that were not only linguistically meaningful but also socially appropriate and contextually relevant to infants' vocalizations as infants developed, which may play a significant role in scaffolding speech and language development.

Verbal Responsiveness in Parents of Toddlers With and Without Autism During a Home Observation

This study examined patterns of verbal responsiveness in parents of toddlers (M_age = 20 months) later identified with autism (n = 121), developmental delay (n = 46), or typical development (n = 44) during an hourlong home observation. Parent verbal responsiveness (PVR) was compared using MANOVA across groups and by child expressive language phase. Multiple regression analyses controlling for child age and maternal education were employed to examine the extent to which PVR predicted variance in concurrent child social communication and prospective language skills. Parents provided synchronous responses approximately 90% of the time. Parents of children with autism and developmental delay used smaller proportions of responses that added linguistic information (i.e., expansions and follow-in directives for language) than those of children with typical development. Parents of children in the preverbal phase were more likely, on average, to affirm their children's acts of intentional communication or provide a follow-in directive for action that did not necessitate a verbal response than to expand or elicit language. Regression results indicated that parental use of expansions and follow-in directives for language made significant contributions to child language outcomes. The patterns we observed may reflect parents' attunement to their child's developmental level. Responsiveness to a child's focus of attention is vital in the earlier stages of language learning; however, results point to the potential importance of parental expansions and follow-in directives for promoting language development across groups in this sample. Directions for intervention research targeting PVR and language skills in toddlers with autism and developmental delays are discussed.

The home language environment and early language ability in rural Southwestern China

Using premier Language Environment Analysis technology to measure and analyze the home language environment, this observational study aims to describe the home language environment and child language ability, drawing on empirical data from 77 households with children aged 18–24 months from rural China. The results show large variation in measures of the home language environment and early language ability, similar to other rural Chinese samples. Results also demonstrate significant correlations between child age and the home language environment, maternal employment and the home language environment, father’s educational attainment and the home language environment, adult–child conversations and early language ability, and child vocalizations and early language ability.

Infant vocalizations elicit simplified speech in childcare

Infant babbling has an important social function in promoting early language development by attracting caregiver attention and prompting parents' contingent, simplified speech, which is more learnable for infants. Here, we demonstrate that prelinguistic infant vocalizations also create learning opportunities for infants in childcare settings by eliciting simplified and more learnable linguistic information during teacher-infant interactions. We compared the rates and complexity of contingent and non-contingent verbal interactions of 34 childcare teachers during a one-on-one free play interaction with a familiar infant under their care (M = 12.6 months old). As compared to non-contingent utterances, teachers' contingent utterances included fewer unique words, a higher proportion of single-word responses, and a shorter mean length of utterances. Teachers did not change their response length based on infants' syllable type and were equally likely to respond to vowels and consonant-vowel vocalizations. Sources of individual differences in the simplification effect related to infant behaviors and teacher characteristics are discussed. The results parallel previous findings demonstrating the simplification effect in parent-infant interactions. That teachers also show this simplification effect when responding to infant vocalizations suggests the power of infant prelinguistic vocalizations for organizing caregiver attention in various settings to elicit simplified, learnable language.

Family-level factors of early childhood development: Evidence from rural China

Family-level factors that characterize the home environment are critical inputs to early language and cognitive development, and potential mechanisms for improving developmental outcomes in vulnerable populations. Many studies conducted in high-income and Western settings highlight stimulating parenting, the home language environment, and parental self-efficacy as possible mechanisms of early development, though less is known about how these family-level factors impact child development in low- or middle-income settings. Even less is known about these family-level factors and early childhood development in rural China, where rates of cognitive and language delay in children aged 0-3 years are as high as 45% and 46%, respectively. Using data collected from 77 rural households with children aged 18-24 months in Southwestern China, this study examines the associations between stimulating parenting, the home language environment, and parental self-efficacy, and early cognitive and language development. The results indicate that stimulating parenting was significantly associated with cognitive, language, and overall development; the home language environment was only significantly associated with language development; and parental self-efficacy was not significantly associated with any developmental outcomes. The implications of such findings reveal mechanisms for supporting healthy child development in rural China.

Early antecedents of emotion differentiation and regulation: Experience tunes the appraisal thresholds of emotional development in infancy

In this review, we synthesize evidence to highlight cognitive appraisal as an important developmental antecedent of individual differences in emotion differentiation and adept emotion regulation. Emotion differentiation is the degree to which emotions are experienced in a nuanced or "granular" way-as specific and separable phenomena. More extensive differentiation is related to positive wellbeing and has emerged as a correlate of emotion regulation skill among adults. We argue that the cognitive appraisal processes that underlie these facets of emotional development are instantiated early in the first year of life and tuned by environmental input and experience. Powerful socializing input in the form of caregivers' contingent and selective responding to infants' emotional signals carves and calibrates the infant's appraisal thresholds for what in their world ought to be noticed, deemed as important or personally meaningful, and responded to (whether and how). These appraisal thresholds are thus unique to the individual child despite the ubiquity of the appraisal process in emotional responding. This appraisal infrastructure, while plastic and continually informed by experience across the lifespan, likely tunes subsequent emotion differentiation, with implications for children's emotion regulatory choices and skills. We end with recommendations for future research in this area, including the urgent need for developmental emotion science to investigate the diverse sociocultural contexts in which children's cognitive appraisals, differentiation of emotions, and regulatory responses are being built across childhood.

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.

Infants who experience more adult-initiated conversations have better expressive language in toddlerhood

To understand how infants become engaged in conversations with their caregivers, we examined who tends to initiate conversations between adults and infants, differences between the features of infant- and adult-initiated conversations, and whether individual differences in how much infants engage in infant- or adult-initiated conversations uniquely predict later language development. We analyzed naturalistic adult-infant conversations captured via passive recording of the daily environment in two samples of 6-month-old infants. In Study 1, we found that at age 6 months, infants typically engage in more adult- than infant-initiated conversations and that adult-initiated conversations are, on average, longer and contain more adult words. In Study 2, we replicated these findings and, further, found that infants who engaged in more adult-initiated conversations in infancy had better expressive language at age 18 months. This association remained significant when accounting for the number of infant-initiated conversations at 6 months. Our findings indicate that early interactions with caregivers can have a lasting impact on children's language development, and that the extent to which parents initiate interactions with their infants may be particularly important.

A systematic review and Bayesian meta-analysis of the development of turn taking in adult-child vocal interactions

Fluent conversation requires temporal organization between conversational exchanges. By performing a systematic review and Bayesian multi-level meta-analysis, we map the trajectory of infants' turn-taking abilities over the course of early development (0 to 70 months). We synthesize the evidence from 26 studies (78 estimates from 429 unique infants, of which at least 152 are female) reporting response latencies in infant-adult dyadic interactions. The data were collected between 1975 and 2019, exclusively in North America and Europe. Infants took on average circa 1 s to respond, and the evidence of changes in response over time was inconclusive. Infants' response latencies are related to those of their adult conversational partners: an increase of 1 s in adult response latency (e.g., 400 to 1400 ms) would be related to an increase of over 1 s in infant response latency (from 600 to 1857 ms). These results highlight the dynamic reciprocity involved in the temporal organization of turn-taking. Based on these results, we provide recommendations for future avenues of enquiry: studies should analyze how turn-by-turn exchanges develop on a longitudinal timescale, with rich assessment of infants' linguistic and social development.