Spanish-speaking caregivers' use of referential labels with toddlers is a better predictor of later vocabulary than their use of referential gestures.

Variation in how frequently caregivers engage with their children is associated with variation in children's later language outcomes. One explanation for this link is that caregivers use both verbal behaviors, such as labels, and non-verbal behaviors, such as gestures, to help children establish reference to objects or events in the world. However, few studies have directly explored whether language outcomes are more strongly associated with referential behaviors that are expressed verbally, such as labels, or non-verbally, such as gestures, or whether both are equally predictive. Here, we observed caregivers from 42 Spanish-speaking families in the US engage with their 18-month-old children during 5-min lab-based, play sessions. Children's language processing speed and vocabulary size were assessed when children were 25 months. Bayesian model comparisons assessed the extent to which the frequencies of caregivers' referential labels, referential gestures, or labels and gestures together, were more strongly associated with children's language outcomes than a model with caregiver total words, or overall talkativeness. The best-fitting models showed that children who heard more referential labels at 18 months were faster in language processing and had larger vocabularies at 25 months. Models including gestures, or labels and gestures together, showed weaker fits to the data. Caregivers' total words predicted children's language processing speed, but predicted vocabulary size less well. These results suggest that the frequency with which caregivers of 18-month-old children use referential labels, more so than referential gestures, is a critical feature of caregiver verbal engagement that contributes to language processing development and vocabulary growth. RESEARCH HIGHLIGHTS: We examined the frequency of referential communicative behaviors, via labels and/or gestures, produced by caregivers during a 5-min play interaction with their 18-month-old children. We assessed predictive relations between labels, gestures, their combination, as well as total words spoken, and children's processing speed and vocabulary growth at 25 months. Bayesian model comparisons showed that caregivers' referential labels at 18 months best predicted both 25-month vocabulary measures, although total words also predicted later processing speed. Frequent use of referential labels by caregivers, more so than referential gestures, is a critical feature of communicative behavior that supports children's later vocabulary learning.

Towards greater transparency in neurodevelopmental disorders research: use of a proposed workflow and propensity scores to facilitate selection of matched groups.

BACKGROUND: Matching is one commonly utilized method in quasi-experimental designs involving individuals with neurodevelopmental disorders (NDD). This method ensures two or more groups (e.g., individuals with an NDD versus neurotypical individuals) are balanced on pre-existing covariates (e.g., IQ), enabling researchers to interpret performance on outcome measures as being attributed to group membership. While much attention has been paid to the statistical criteria of how to assess whether groups are well-matched, relatively little attention has been given to a crucial prior step: the selection of the individuals that are included in matched groups. The selection of individuals is often an undocumented process, which can invite unintentional, arbitrary, and biased decision-making. Limited documentation can result in findings that have limited reproducibility and replicability and thereby have poor potential for generalization to the broader population. Especially given the heterogeneity of individuals with NDDs, interpretation of research findings depends on minimizing bias at all stages of data collection and analysis. RESULTS: In the spirit of open science, this tutorial demonstrates how a workflow can be used to provide a transparent, reproducible, and replicable process to select individuals for matched groups. Our workflow includes the following key steps: Assess data, Select covariates, Conduct matching, and Diagnose matching. Our sample dataset is from children with autism spectrum disorder (ASD; n = 25) and typically developing children (n = 43) but can be adapted to comparisons of any two groups in quasi-experimental designs. We work through this method to conduct and document matching using propensity scores implemented with the R package MatchIt. Data and code are publicly available, and a template for this workflow is provided in the Additional file 1 as well as on a public repository. CONCLUSIONS: It is important to provide clear documentation regarding the selection process to establish matched groups. This documentation ensures better transparency in participant selection and data analysis in NDD research. We hope the adoption of such a workflow will ultimately advance our ability to replicate findings and help improve the lives of individuals with NDDs.

Off to a good start: Early Spanish-language processing efficiency supports Spanish- and English-language outcomes at 4½ years in sequential bilinguals.

Many Latino children in the U.S. speak primarily Spanish at home with few opportunities for exposure to English before entering school. For monolingual children, the strongest early predictor of later school success is oral language skill developed before kindergarten. Less is known about how early oral language skills support later learning in sequential bilingual children. A question with wide-reaching significance is whether skill in a child's first language (L1) supports later learning in a second language (L2). In this longitudinal study of sequential Spanish-English bilinguals, we assessed oral language skills in Spanish at 2 years through parent reports of vocabulary size and children's real-time language processing efficiency (Accuracy, RT) in the 'looking-while-listening' (LWL) task. At 4½ years, we assessed language outcomes in both Spanish and English using standardized tests. Reported relative exposure to each language was significantly correlated with language outcomes in Spanish and English. Within-language relations were observed between Spanish vocabulary size and processing efficiency at 2 years and later Spanish-language outcomes. Critically, across-language relations were also observed: Children with stronger Spanish-language processing efficiency at 2 years had stronger English-language skills at 4½ years, controlling for socioeconomic status and exposure to English. Children's early language processing efficiency in Spanish is associated with stronger real-time information processing skills that support maintenance of Spanish and learning in English when these children enter school. These results support the recommendation that primarily Spanish-speaking families should engage in activities that promote children's Spanish-language skills while also seeking opportunities for children to be exposed to English.

Longform recordings of everyday life: Ethics for best practices.

Recent advances in large-scale data storage and processing offer unprecedented opportunities for behavioral scientists to collect and analyze naturalistic data, including from underrepresented groups. Audio data, particularly real-world audio recordings, are of particular interest to behavioral scientists because they provide high-fidelity access to subtle aspects of daily life and social interactions. However, these methodological advances pose novel risks to research participants and communities. In this article, we outline the benefits and challenges associated with collecting, analyzing, and sharing multi-hour audio recording data. Guided by the principles of autonomy, privacy, beneficence, and justice, we propose a set of ethical guidelines for the use of longform audio recordings in behavioral research. This article is also accompanied by an Open Science Framework Ethics Repository that includes informed consent resources such as frequent participant concerns and sample consent forms.

Language nutrition for language health in children with disorders: a scoping review.

The quantity and quality of child-directed speech-language nutrition-provided to typically-developing children is associated with language outcomes-language health. Limited information is available about child-directed speech to children at biological risk of language impairments. We conducted a scoping review on caregiver child-directed speech for children with three clinical conditions associated with language impairments-preterm birth, intellectual disability, and autism-addressing three questions: (1) How does child-directed speech to these children differ from speech to typically-developing children? (2) What are the associations between child-directed speech and child language outcomes? (3) How convincing are intervention studies that aim to improve child-directed speech and thereby facilitate children's language development? We identified 635 potential studies and reviewed 57 meeting study criteria. Child-directed speech to children with all conditions was comparable to speech to language-matched children; caregivers were more directive toward children with disorders. Most associations between child-directed speech and outcomes were positive. However, several interventions had minimal effects on child language. Trials with large samples, intensive interventions, and multiple data sources are needed to evaluate child-directed speech as a means to prevent language impairment. Clinicians should counsel caregivers to use high quality child-directed speech and responsive communication styles with children with these conditions.

Learning language in autism: maternal linguistic input contributes to later vocabulary.

It is well established that children with typical development (TYP) exposed to more maternal linguistic input develop larger vocabularies. We know relatively little about the linguistic environment available to children with autism spectrum disorders (ASD), and whether input contributes to their later vocabulary. Children with ASD or TYP and their mothers from English and French-speaking families engaged in a 10 min free-play interaction. To compare input, children were matched on language ability, sex, and maternal education (ASD n = 20, TYP n = 20). Input was transcribed, and the number of word tokens and types, lexical diversity (D), mean length of utterances (MLU), and number of utterances were calculated. We then examined the relationship between input and children's spoken vocabulary 6 months later in a larger sample (ASD: n = 19, 50-85 months; TYP: n = 44, 25-58 months). No significant group differences were found on the five input features. A hierarchical multiple regression model demonstrated input MLU significantly and positively contributed to spoken vocabulary 6 months later in both groups, over and above initial language levels. No significant difference was found between groups in the slope between input MLU and later vocabulary. Our findings reveal children with ASD and TYP of similar language levels are exposed to similar maternal linguistic environments regarding number of word tokens and types, D, MLU, and number of utterances. Importantly, linguistic input accounted for later vocabulary growth in children with ASD.

Brief report: Conveying subjective experience in conversation: production of mental state terms and personal narratives in individuals with high functioning autism.

Mental state terms and personal narratives are conversational devices used to communicate subjective experience in conversation. Pre-adolescents with high-functioning autism (HFA, n = 20) were compared with language-matched typically-developing peers (TYP, n = 17) on production of mental state terms (i.e., perception, physiology, desire, emotion, cognition) and personal narratives (sequenced retelling of life events) during short conversations. HFA and TYP participants did not differ in global use of mental state terms, nor did they exhibit reduced production of cognitive terms in particular. Participants with HFA produced significantly fewer personal narratives. They also produced a smaller proportion of their mental state terms during personal narratives. These findings underscore the importance of assessing and developing qualitative aspects of conversation in highly verbal individuals with autism.