This study will investigate how children acquire the option to drop the subject of a sentence, or null subjects (e.g., “Tickles me” instead of “He tickles me”). In languages that do not permit null subjects, children produce sentences with null subjects from 1 to 3 years of age. This non-adultlike production has been explained by two main accounts: first, the null subject sentences may accurately reflect the children’s linguistic knowledge, that is, a competence account. Alternatively, they may result from immature processing resources, therefore underestimating children’s competence, that is, a performance account. We will test the predictions of these accounts by using a central fixation preference procedure and elicited imitation to measure children’s comprehension and production, respectively, in monolingual 19- to 28-month-olds acquiring English (a non-null subject language) and Italian (a null subject language). The results will shed light on acquisition across languages, and the features that provide evidence to a learner.

By comparing infant-directed speech to spouse- and dog-directed talk, we aimed to investigate how pitch and utterance length are modulated by speakers considering the speech context and the partner’s expected needs and capabilities. We found that mean pitch was modulated in line with the partner’s attentional needs, while pitch range and utterance length were modulated according to the partner’s expected linguistic competence. In a situation with a nursery rhyme, speakers used the highest pitch and widest pitch range with all partners suggesting that infant-directed context greatly influences these acoustic features. Recent findings showed that these speakers expressed more intense positive emotions towards their infants and spouses than towards their dogs. Our results revealed different patterns, leading us to conclude that these acoustic features are not simple by-products of emotional speech. Instead, they are dynamically and functionally used in accordance with the speech context and the audience’s expected needs and capabilities.

It is important to assess learning in both familiar and unfamiliar conditions to determine the extent of learning generalisation. In this study, we evaluated parent language outcomes of LENA Start™, a parent-implemented intervention, using distal measures derived from a parent–child free play interaction.

Forty-four parents and their child (mean: 20.8 months) participated in LENA Start™ or early childhood education curriculum intervention, in either English (n = 34) or Spanish (n = 10). We completed between- and within-group analyses using language and communication behaviour measures derived from parent–child interactions elicited outside the home with researcher-supplied materials (i.e., distal measures).

Group comparisons revealed significant differences on a subset of behavioural measures. Spanish-speaking parents in the LENA Start™ group demonstrated significant gains on three measures. While LENA Start™ has been associated with parent gains on proximal language measures, the results of this study reveal limited generalisation of skills based on distal measures.

We explored whether bilingual toddlers make use of semantic and phonological overlap between their languages to learn new words. We analysed cross-sectional and longitudinal CDI data on the words understood and produced by 1.0 to 3.0-year-old bilingual toddlers with English and one additional language. Cognates were more likely to be understood and produced compared to non-cognates. Cognate effects were modulated by whether the toddler knew the translation equivalent in the other language, highlighting that young learners are sensitive to the similarities across their languages. Additionally, exploratory analyses suggest that children with smaller vocabularies rely more on translation equivalents to support the acquisition of difficult words. Children with larger vocabulary sizes exhibited no preference for translation equivalents in comprehension, and a preference for new concepts in production. The rapid acceleration of vocabulary growth in the second year of life may explain this developmental change in translation equivalent preference.

This study is one of the few research efforts investigating unexpected non-interactive foreign language acquisition in children with Autism Spectrum Disorder (ASD). Participants included 46 English-Hebrew-speaking children (ages 4;10 to 12;0): 14 autistic children who acquired English via non-interactive input (ASD-NI); 12 autistic children (ASD-Nat), and 20 non-autistic children with typical language development (TLD-Nat) who acquired English and Hebrew naturalistically. Morpho-syntactic abilities were assessed using Sentence Repetition tasks in both languages. The results showed no group differences for morpho-syntax in English; in Hebrew, the ASD-NI group scored similarly to the ASD-Nat group but lower than the TLD-Nat group. Individual performance differences between Hebrew and English were observed across all groups. Additionally, correlations between exposure and SRep scores were found in both groups for Hebrew but not English. These findings highlight diverse paths to language acquisition in ASD, with children acquiring foreign languages via both naturalistic and non-interactive input.

In this longitudinal study, we compare the age of reaching early developmental milestones in bilingual and monolingual children and between the bilinguals’ two languages. We present data from 302 Polish bilinguals (living outside of Poland with various majority languages) and 302 Polish monolinguals, aged M = 12.78 months on study entry (range: 0–24 months), matched on sex, age at study entry, duration of parental reporting, and parental education. The milestones under investigation include crawling, walking, babbling, first, 10th, 50th word, and first multi-word utterances. The data was collected with a specially designed mobile app, in which parents reported their children’s development repeatedly. Using this relatively big sample and looking at a wide range of investigated milestones, we present evidence that typical bilingual development follows a trajectory similar to monolingual development. We also evaluate the feasibility and usefulness of online data collection using mobile apps to study early language development.

Using the syntactic priming paradigm, this study investigated abstract syntactic knowledge of Chinese transitive structures (i.e., subject-verb-object [SVO], BA, and BEI) in deaf children with cochlear implants (CIs). Specifically, we focused on the differences in the development of various syntactic structures (within CI children and compared with their typically hearing children) and the possible individual differences during this process. Results showed that both CI and hearing children exhibited structural priming for all syntactic structures (i.e., SVO, SbaOV structure [agent-patient ordering], and ObeiSV structure [patient-agent ordering]) after comprehending and repeating the prime sentence regardless of verb repetition. However, verb repetition induced an intense abstract priming effect in CI children but not hearing children, with the lexical boost effect more significant for SVO and BA structures. In addition, CI children’s working memory capability modulated the production of the BA structure but not SVO and BEI structures.

The Arabic development of Syrian refugee children (N = 133; mean age = 9;4 at Time 1) was examined over 3 time periods during their first five years in Canada. Children were administered sentence repetition and receptive vocabulary tasks in English and Arabic, and information about age-of-arrival (AOA), schooling in Arabic and language environment factors was obtained via parent report. Older AOA was associated with superior Arabic abilities across time, but regardless of AOA, children showed plateau/attrition patterns in Arabic and shifts to English dominance by Time 3. Increases in English over Arabic were observed for language use at home and language-rich activities overtime. Stronger Arabic Time 3 outcomes were predicted by more Arabic and less English use with siblings, more schooling in Arabic, more frequent listening-speaking and extra-curricular activities in Arabic, and more Arabic use with friends. We conclude that the heritage language can be vulnerable even for first-generation bilinguals.

A growing body of research has found that talking to young children is positively associated with language outcomes. However, there is tremendous heterogeneity in the design of these studies, which could potentially affect the strength and reliability of this association. The present meta-analysis, comprising 4760 participants across 71 studies, goes beyond prior research by including: 1) more recent studies, 2) non-English-speaking populations, 3) more fine-grained categorization of measures of input, 4) additional moderators, and 5) a multilevel model design allowing us to consider multiple effect sizes per study. We find a moderate association between input and outcomes (R2=0.04-0.07) across four input measures, with some evidence of publication bias. We find no differences in effect size across any of the input measures. Child age and study duration moderated some effects of input. Our findings suggest that language input-outcome associations remain robust but modest across a multitude of contexts and measures.

Speakers consider their listeners and adjust the way they communicate. One well-studied example is the register of infant-directed speech (IDS), which differs acoustically from speech directed to adults. However, little work has explored how parents adjust speech to infants across different contexts. This is important because infants and parents engage in many activities throughout each day. The current study tests whether the properties of IDS in English vary across three in-lab tasks (sorting objects, free play, and storytelling). We analysed acoustic features associated with prosody, including mean fundamental frequency (F0, perceived as pitch), F0 range, and word rate. We found that both parents’ pitch ranges and word rates varied depending on the task in IDS. The storytelling task stood out among the tasks for having a wider pitch range and faster word rate. The results depict how context can drive parents’ speech adjustments to infants.