Children acquire vocabulary at different growth rates. The aim of this study was to identify subgroups of different vocabulary trajectories in a community sample of L1 German-speaking children aged 1;6 to 3;0 to enlarge the understanding of vocabulary trajectories. Parents filled out vocabulary checklists at four measurement times, each six months apart. Growth mixture modelling was used to naturally determine latent classes of observed vocabulary growth curve patterns. Six distinct trajectories of vocabulary growth were identified and characterised. Children’s (N=198) vocabulary abilities were divided into the following subgroups: “far above average” (2.0%), “above average” (6.6%), “typical” (70.2%), “below average” (14.1%), “early below average" but caught up with their peers over time (5.6%), and “far below average” (1.5%). Socioeconomic status differed significantly between subgroups.

The current study examined the relationship between interest, the home environment, and young Chinese children’s development of English as a second/foreign language in Hong Kong. Two hundred and seventy-four Hong Kong kindergartners were assessed on their interest in learning English and their English language skills (i.e., expressive and receptive vocabulary). Their parents completed questionnaires eliciting family socio-economic status, parental beliefs, and home learning environment. The results indicated that (1) interest was related to children’s English language abilities after controlling for children’s gender, non-verbal intelligence, and kindergarten type; (2) parents’ beliefs about their child’s English ability and self-efficacy were related to children’s interest in learning English; and (3) interest uniquely contributed to children’s English language ability in the home environment. The present findings provide evidence of the active role that children play in their second/foreign language development and highlight the significant influence of parental beliefs on children’s interest in learning English.

Infants’ language is often measured indirectly via parent reports, but mothers may underestimate or overestimate their infants’ word comprehension. The current study examined estimations of mothers from diverse educational backgrounds regarding their infants’ word comprehension and how these estimations are associated with their verbal input and infants’ receptive vocabulary at 14 months. We compared 34 infants’ looking-while-listening (LWL) performances with the mothers’ Turkish Communicative Development Inventory (TCDI) reports to calculate the mothers’ overestimation and underestimation. During free-play sessions, we assessed the mothers’ number of words, number of clauses, lexical diversity, and linguistic complexity. We found that mothers have overestimations and underestimations regardless of their educational background. Crucially, mothers’ only overestimations were positively associated with their number of words and lexical diversity. Mothers’ verbal input was not related to infants’ receptive vocabulary scores. The findings suggest that mothers’ input might be aligned with their estimations of their infants’ language capabilities, which might not reflect the infants’ true performance.

This study investigates Navajo verbs produced by four children, ages 4;07 to 11;02, during conversations with their caretakers. Analyses of 1600 verbs demonstrate that the bisyllabic verb form, consisting of a verb stem and a portion of the prefix string, is the most common pattern produced by the children. This indicates that Navajo-speaking children use meaningful units of verbal morphology that do not necessarily adhere to the linguistic boundaries normally ascribed to the Navajo verb complex. Further, the verbs are primarily intransitive and third-person singular constructions, which are minimally inflected. It is argued that these minimally-inflected verb forms are frequent not just because they are simpler, but also because they are highly productive as main verbs and are used to create phrasal verbs and nouns. These findings contribute to our general understanding of language development and to the growing body of research investigating children’s acquisition of endangered Indigenous languages.

This study investigates Mandarin-speaking children’s (age 3–7) comprehension development of novel and conventional metonymy, combining online and offline methods. Both online and offline data show significantly better performances from the oldest group (6-to-7-year-old) and a delayed acquisition of conventional metonymy compared with novel metonymy. However, part of offline data shows no significant difference between adjacent age groups, while the eye-tracking data show a chronological development from age 3–7. Furthermore, in offline tasks, the three-year-old group features a high choice randomness and the four-to-five-year-olds show the longest reaction time. Therefore, we argue that, not only age but also metonymy type can influence metonymy acquisition, and that a lack of socio-cultural experience can be a source of acquisition difficulty for children under six. Methodologically speaking, we believe that online methods should not be considered superior to offline ones as they investigate different aspects of implicit and explicit language comprehension.

Research shows that children’s home environment (e.g., the composition of their household and the resources available in it) has an impact on children’s language development. However, this research has mostly been conducted among English speakers from the minority world and has often only considered vocabulary size. This exploratory study investigated whether home environment factors are predictive of grammar development in Afrikaans-speaking (n = 117) and English-speaking (n = 102) toddlers in South Africa. Moreover, potential differences between these two language groups were explored. Results showed that home environment factors pertaining to family stability predicted two of the three grammar scores, namely total grammar and complex phrases. Cluster analysis showed distinct patterns of home environment factors between Afrikaans and English-speaking households, illustrating the importance of measuring these factors even across samples from the same country. This study shows that children’s home environment is an interconnected system and cautions against oversimplified single-factor approaches.

Private speech is a tool through which children self-regulate. The regulatory content of children’s overt private speech is associated with response to task difficulty and task performance. Parenting is proposed to play a role in the development of private speech as co-regulatory interactions become represented by the child as private speech to regulate thinking and behaviour. This study investigated the relationship between maternal parenting style and the spontaneous regulatory content of private speech in 3- to 5-year-old children (N = 70) during a problem-solving Duplo construction task. Sixty-six children used intelligible private speech which was coded according to its functional self-regulatory content (i.e., forethought, performance, and self-reflective). Mothers completed the Australian version of the Parenting Styles and Dimensions Questionnaire. Results revealed a significant positive association between maternal authoritative parenting and the frequency and proportion of children’s forethought type (i.e., planning and self-motivational) utterances during the construction task. There were no significant associations between maternal parenting style and other private speech content subtypes.

This study investigated the role of temperament in oral language development in over 200 Mandarin and Cantonese speakers in the Growing Up in New Zealand pre-birth longitudinal cohort study. Mothers assessed infant temperament at nine months using a five-factor Infant Behaviour Questionnaire-Revised Very Short Form. They also reported on children’s vocabulary and word combinations at age two using adapted MacArthur-Bates Communicative Development Inventory short forms. Regression analyses were employed to examine unique links between infant temperament and language, respectively, controlling for demographic factors. Fear was associated with larger English vocabularies for English-Mandarin speakers and larger Cantonese vocabularies for Cantonese speakers. Orienting capacity was associated with more advanced word combinations for Mandarin speakers, whereas negative emotionality was associated with less advanced word combinations for Cantonese speakers. Positive affect/surgency was associated with more advanced word combinations for English-Cantonese speakers. This study revealed predictive patterns of infant temperament across Chinese-speaking children’s multiple languages.

We report findings from a corpus-based investigation of three young children growing up in German-English bilingual environments (M = 3;0, Range = 2;3–3;11). Based on 2,146,179 single words and two-word combinations in naturalistic child speech (CS) and child-directed speech (CDS), we assessed the degree to which the frequency distribution of CDS predicted CS usage over time, and systematically identified CS that was over- or underrepresented in the corpus with respect to matched CDS baselines. Results showed that CDS explained 61% of the variance in CS single-word use and 19.3% of the variance in two-word combinations. Furthermore, the bilingual nature of the over or -underrepresented CS was partially attributable to factors beyond the corpus statistics, namely individual differences between children in their bilingual learning environment. In two out of the three children, overrepresented two-word combinations contained higher levels of syntactic slot redundancy than underrepresented CS. These results are discussed with respect to the role that redundancy plays in producing semiformulaic slot-and-frame patterns in CS.

Both the quantity and quality of the maternal language input are important for early language development. However, depression and anxiety can negatively impact mothers’ engagement with their infants and their infants’ expressive language abilities. Australian mother-infant dyads (N = 30) participated in a longitudinal study examining the effect of maternal language input when infants were 24 and 30 months and maternal depression and anxiety symptoms on vocabulary size. Half the mothers had elevated depression and anxiety symptoms during at least one point in the study (at 6, 12, 18, 24, or 30 months). The results showed that only maternal input measures (word tokens, types, and mean length of utterance) predicted vocabulary size. While no evidence was found that brief periods of maternal depression and anxiety negatively impacted early vocabulary development, the findings highlight the critical importance and possible mitigating effects of maintaining good quality mother–infant interactions during early development.

We characterised language samples collected remotely from typically developing three-year-olds by comparing them against independent language samples collected in person from age-matched peers with and without language delays. Forty-eight typically developing, English-learning three-year-olds were administered a picture description task via Zoom. The in-person comparison groups were two sets of independent language samples from age-matched typically developing as well as language-delayed children available on the Child Language Data Exchange System. The findings show that although language samples collected remotely from three-year-olds yield numerically dissimilar lexical and grammatical measures compared to samples collected in person, they still consistently distinguish toddlers with and without language delays.

This study investigates the interrelationship between gender-shift in child-directed speech (CDS), child gender, and parenting styles among Arabic-speaking caregivers. A survey of 180 Palestinian parents assessed their parenting styles and reported use of gender-shift in relation to their child’s gender. The findings reveal no significant correlation between gender-shift and child’s gender. However, a positive association exists between gender-shift and indulgence, a characteristic of permissive parenting, while a negative correlation is seen with autonomy granting, regulation, and warmth/support, central to authoritative parenting. These results highlight the need for detailed analysis of parenting dimensions towards deeper understanding of the role of gender-shift use in Arabic CDS, suggesting that broader parenting style categories might overlook crucial differences. The study emphasizes the importance of culturally and linguistically sensitive, interprofessional approaches in language development research, especially in relatively unexplored areas like CDS, while also acknowledging the complexities of exploring such relatively unexamined areas.

The present study investigated whether children’s difficulty with non-canonical structures is due to their non-adult-like use of linguistic cues or their inability to revise misinterpretations using late-arriving cues. We adopted a priming production task and a self-paced listening task with picture verification, and included three Mandarin non-canonical structures with differing word orders and the presence or absence of morphosyntactic cues. Forty five-to-ten-year-old Mandarin-speaking children were tested and compared to adults. Results showed that children were indistinguishable from adults in how they used different cues in real-time, although their performance in offline comprehension and production was more prone to errors but improved given the increase of age. These results suggest that the current child sample has adult-like cue-use patterns and use late-arriving cues to revise misinterpretations. The observed worse offline accuracy and production difficulties relative to adults result from their less developed domain-general abilities in performing tasks.

Factors which impact bilingual language development can often interact with different language features. The current study teases apart the impact of internal and external factors (chronological age, length of exposure, L2 richness, L2 use at home, maternal education and maternal L2 proficiency) across linguistic domains and features (vocabulary, morphology and syntax). Participants were 40 Arabic-speaking sequential bilinguals acquiring English (5;7-12;2, M = 8;4). Length of exposure predicted vocabulary and morphology, while chronological age predicted syntax. L2 richness also predicted vocabulary and syntax, although the impact on syntax was selective across structures. This split between syntax on the one hand, and vocabulary and morphology on the other, reflects the more embedded properties of the former; this contrasts with vocabulary and morphology, where transfer from the L1 and L2 may be more strongly dependent on the availability of shared forms across languages. Further implications are considered for sequential bilinguals in education contexts.

This study explored monolingual and multilingual two- to five-year-olds’ reliance on a non-verbal and a verbal cue during word-referent mapping, in relation to vocabulary knowledge and, for the multilinguals, Dutch language exposure. Ninety monolingual and sixty-seven multilingual children performed a referential conflict experiment that pitted a non-verbal (pointing) cue and a verbal (mutual exclusivity) cue. Mixed-effect regressions showed no main effects of vocabulary and language exposure. An interaction between vocabulary and group showed that lower vocabulary scores were associated with a stronger reliance on pointing over mutual exclusivity for multilinguals (but not monolinguals). Furthermore, an interaction between vocabulary, language exposure, and cue word (novel vs. familiar label) indicated that multilinguals with lower exposure and lower vocabulary showed a stronger reliance on pointing over mutual exclusivity when a novel rather than familiar word was used. These findings suggest that multilingual and monolingual children go through different trajectories when learning to map words to referents.

Research on the language acquisition of deaf individuals who are exposed to accessible linguistic input at a variety of ages has provided evidence for a sensitive period of first language acquisition. Recent studies have shown that deaf individuals who first learn language after early childhood, late first-language learners (LL1), do not comprehend reversible Subject-Verb-Object (SVO) sentences. The present study analyzed 478 signed productions elicited with pictures depicting simple events with one or two arguments by 28 signers. The argument order patterns of native signers converged with one another and the word order patterns of American Sign Language (ASL). By contrast, the ordering patterns of the LL1 signers did not converge with one another or with the patterns of the native signers. This indicates that early childhood is a period of heightened sensitivity to basic word order and may help explain why complex structures are difficult for LL1 signers to learn.

This study explored the use of sophisticated vocabulary, complex syntax, and decontextualized language (including book information, conceptual information, past/future experiences, and vocabulary information) in teachers’ instructional interactions with children during the literacy block in prekindergarten and kindergarten classrooms. The sample included 33 teachers and 421 children. We examined correlations among these language features and their unique contributions to children’s vocabulary learning. Teachers who used more sophisticated vocabulary also engaged in more decontextualized talk about vocabulary and past/future experiences. Additionally, teachers’ use of complex syntax was uniquely associated with talk about conceptual information. Both complex syntax and conceptual information talk predicted children’s vocabulary learning; however, complex syntax emerged as the sole predictor when accounting for this relationship. This finding suggests that decontextualized talk about concepts, characterized by complex language structures, may facilitate vocabulary acquisition.

Usage-based theories of children’s syntactic acquisition (e.g., Tomasello, 2000a) predict that children’s abstract lexical categories emerge from their experience with particular words in constructions in their input. Because modifiers in English are almost always prenominal, children might initially treat adjectives similarly to nouns when used in a prenominal position. In this study, we taught English-speaking preschoolers (between 2 and 6 years) novel nouns (object labels) and adjectives (words referring to attributes) in both prenominal and postnominal positions. The children corrected both postnominal adjectives and nouns to prenominal position, but corrected modifying nouns more often than adjectives. These results suggest that children differentiate between nouns and adjectives even when they occur in the same position and serve the same function (i.e., modification). Children were increasingly likely to correct postnominal adjectives (not nouns) with increasing age. We argue that children attend to word order more when it makes a difference in meaning.

This retrospective study provides insights on linguistic development in exceptional circumstances assessing 378 children (between 2;6 and 3;6) who lived their first years during the COVID-19 pandemic and comparing it with normative data collected before this period (CDI-III-PT; Cadime et al., 2021). It investigates the extent to which linguistic development was modulated by a complex set of factors, including sex, maternal education, book reading, language-promoting practices, COVID-19 infection, parental stress and sleeping problems, considering three periods (during lockdowns, out of lockdowns and at present). The results show a substantial negative effect of the pandemic on both lexical and syntactic development. Considering individual variation, structural equation modelling unveiled a complex scenario in which age, sex, book reading, language-promoting practices, sleeping problems and COVID-19 infection showed a direct effect on linguistic development. Maternal education and parental stress had an indirect effect on children’s language, mediated by book reading and sleeping problems, respectively.

Children acquiring Japanese differ from those acquiring English with regard to the rate at which verbs are learned (Fernald & Morikawa, 1993). One possible explanation is that Japanese caregivers use verbs in referentially transparent contexts, which facilitate the form-meaning link. We examined this hypothesis by assessing differences in verb usage by Japanese and American caregivers during dyadic play with their infants (5-22 months). We annotated verb-containing utterances for elements associated with referential transparency and compared across groups. Contrary to our hypotheses, we found that Japanese caregivers used verbs in fewer referentially transparent contexts than American caregivers, or did not significantly differ from American caregivers, depending on the measure. These findings cast doubt on cross-cultural differences in referential transparency between Japanese and American child-directed input.