Children’s acquisition of variation in the target language depends on a number of factors not yet well understood. This study probes the acquisition of morphological variation in two unrelated languages, Croatian (Slavic) and Estonian (Finnic), focussing on parallel forms of a lexeme expressing a single grammatical category (a phenomenon known as morphological overabundance). We conducted a cross-linguistic elicitation experiment with 140 monolingual, typically developing children aged 3;0 to 6;11 (80 learning Croatian, 60 Estonian). We elicited genitive plural forms in Croatian and partitive plural in Estonian, with lexemes which either are invariant or allow more than one form. Children in both languages were less accurate with lexemes with parallel forms, indicating that the morphological variation hindered acquisition. Pattern type frequency was found to affect accuracy in both languages. Children’s choice between two parallel forms was unaffected by age, but significant language-specific differences emerged.

This study evaluates how language exposure and mothers’ language dominance relate to infants’ early bilingual vocabulary development in a low-socioeconomic status (SES) sample from an understudied population: Mexican Indigenous bilinguals. Thirty-two mother–child dyads participated. All mothers were bilingual speakers of Spanish and one of Mexican Indigenous languages, including Zapotec, Mixtec, and Otomi. Infants’ (between 16 and 37 months) vocabulary size was estimated in both languages using the Mexican Spanish version of the MacArthur-Bates CDI II. Infants’ language exposure, mothers’ bilingual profile, and their SES were estimated on numerical scales. The results of Spearman correlations showed infants’ vocabulary size in Spanish grows with age, while their vocabulary in the Indigenous language depends on relative language exposure. Mothers’ language dominance correlated with Indigenous language exposure and infants’ vocabulary size in the Indigenous language. These findings are discussed in the context of early bilingual vocabulary acquisition in speakers of minority languages.

Irony comprehension requires going beyond literal meaning of words and is challenging for children. In this pre-registered study, we investigated how teaching metapragmatic knowledge in classrooms impacts written irony comprehension in 10-year-old Finnish-speaking children (n = 41, 21 girls) compared to a control group (n = 34, 13 girls). At pre-test, children read ironic and literal sentences embedded in stories while their eye movements were recorded. Next, the training group was taught about irony, and the control group was taught about reading comprehension. At post-test, the reading task and eye-tracking were repeated. Irony comprehension improved after metapragmatic training on irony, suggesting that metapragmatic knowledge serves an important role in irony development. However, the eye movement data suggested that training did not change the strategy children used to resolve the ironic meaning. The results highlight the potential of metapragmatic training and have implications for theories of irony comprehension.

Despite the importance of cognitive development for vocabulary acquisition, limited attention has been given to the impacts of cognitive factors on this phenomenon from a longitudinal perspective. This study evaluates the longitudinal development of such factors (i.e. metacognitive knowledge, working memory, and non-verbal intelligence) and L2 vocabulary knowledge growth in 210 young second language learners enrolled in a bilingual programme in China. Results supported individual differences in the initial level and the growth rate of learners’ cognitive development and vocabulary knowledge growth: a higher starting level of cognitive development correlated with a higher level of vocabulary knowledge and a faster rate of vocabulary knowledge growth. Findings revealed particularly significant predictive role of metacognitive knowledge on vocabulary knowledge, followed by non-verbal intelligence and working memory. Relevant implications were discussed based on the findings.

Numerous developmental findings suggest that infants and toddlers engage predictive processing during language comprehension. However, a significant limitation of this research is that associative (bottom-up) and predictive (top-down) explanations are not readily differentiated. Following adult studies that varied predictiveness relative to semantic-relatedness to differentiate associative vs. predictive processes, the present study used eye-tracking to begin to disentangle the contributions of bottom-up and top-down mechanisms to infants’ real-time language processing. Replicating prior results, infants (14-19 months old) use successive semantically-related words across sentences (e.g., eat, yum, mouth) to predict upcoming nouns (e.g., cookie). However, we also provide evidence that using successive semantically-related words to predict is distinct from the bottom-up activation of the word itself. In a second experiment, we investigate the potential effects of repetition on the findings. This work is the first to reveal that infant language comprehension is affected by both associative and predictive processes.

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.

Words said aloud are typically recalled more than words studied under other techniques. In certain circumstances, production does not lead to this memory advantage. We investigated the nature of this effect by varying the task during learning. Children aged five to six years were trained on novel words which required no action (Heard) compared to Verbal-Speech (production), Non-Verbal-Speech (stick out tongue), and Non-Verbal-Non-Speech (touch nose). Eye-tracking showed successful learning of novel words in all training conditions, but no differences between conditions. Both non-verbal tasks disrupted recall, demonstrating that encoding can be disrupted when children perform different types of concurrent actions.

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.

Although family factors are considered important for children’s language acquisition, the evidence comes primarily from affluent societies. Thus, this study aimed to examine the relations between family factors (family’s socioeconomic status [SES], home literacy activities, access to print resources, and parental beliefs) and children’s vocabulary knowledge in both urban and rural settings in China. Data from 366 children (urban group: 109, 4.85 years; rural group: 257, 4.89 years) were collected. Results showed that whereas family’s SES significantly predicted access to print resources and children’s vocabulary knowledge in the rural group, parental beliefs directly predicted children’s vocabulary knowledge in the urban group. Multigroup analysis showed that the associations of family’s SES and access to print resources with children’s vocabulary knowledge were stronger in the rural group than in the urban group. Our findings highlight the importance of considering contextual settings when conceptualising the role of family factors in children’s language acquisition.

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.

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 investigated the dynamics of communicative initiation in infant−caregiver interactions across ages and language abilities. Analyses of 228 Language ENvironment Analysis (LENA) recordings from 141 Korean adult−child dyads (60 girls; aged 7−30 months) replicated the initiator effect reported in North American populations. This effect, demonstrated by longer utterances, more frequent speech, and shorter response times in self-initiated interactions for both children and adults, suggests potential cross-cultural consistency in this conversational dynamic and remained consistent across ages in most conversational measures. A focused analysis of 13–14 month-olds (N = 40) and their K-CDI scores revealed that the initiator effect in segment duration and number persisted across most vocabulary percentiles. Additionally, nuanced findings indicated that caregivers increased their input frequency and adjusted segment duration in adult-initiated conversations in tandem with children’s higher receptive abilities. The robustness of the initiator role across cultures, ages, and vocabulary abilities points to a fundamental aspect of human communication.

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.

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.

English-speaking children sometimes make errors in production and comprehension of biclausal questions, known as “Scope-Marking Errors”. In production, these errors surface as medial wh questions (e.g., What do you think who the cat chased? (Thornton, 1990)). In comprehension, children respond to questions like How did the boy say what he caught? by answering what was caught (de Villiers & Roeper, 1995). These errors resemble wh-scope marking questions, attested in languages like German. Together, these errors suggest temporary adoption of multiple UG-licensed grammars (e.g., Yang, 2002). However, Lutken et al. (2020) found that children who make these errors in production do not necessarily make errors in comprehension and vice versa. They suggest these errors stem from children’s immature processing mechanisms. This article examines children’s production, comprehension, and processing capabilities, specifically working memory (WM). We find a correlation between WM and error rate and suggest separate causes for production and comprehension errors.

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.

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.

To investigate how a high risk for infant neurological impairment affects the quality of infant verbal interactions, and in particular properties of infant-directed speech, spontaneous interactions between 14 mothers and their 4.5-month-old infants at high risk for neurological disorders (7 female) were recorded and acoustically compared with those of 14 dyads with typically developing infants (8 female). Mothers of at-risk infants had proportionally less voicing, and the proportion of voicing decreased with increasing severity of the infants’ long-term outcome. Follow-up analysis based on manual annotation of phonation style revealed breathy phonation as more common toward infants with more severe long-term outcomes (N=7; 44.7% of speech) than controls (N=14; 22.0%; p=0.005) or at-risk infants with typical or mildly abnormal long-term outcomes (N=7; 16.5%; p=0.002). The results indicate that maternal phonation style during early dyadic interactions is affected by the infant’s neurological condition.

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.