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.

From early on, infants show a preference for infant-directed speech (IDS) over adult-directed speech (ADS), and exposure to IDS has been correlated with language outcome measures such as vocabulary. The present multi-laboratory study explores this issue by investigating whether there is a link between early preference for IDS and later vocabulary size. Infants’ preference for IDS was tested as part of the ManyBabies 1 project, and follow-up CDI data were collected from a subsample of this dataset at 18 and 24 months. A total of 341 (18 months) and 327 (24 months) infants were tested across 21 laboratories. In neither preregistered analyses with North American and UK English, nor exploratory analyses with a larger sample did we find evidence for a relation between IDS preference and later vocabulary. We discuss implications of this finding in light of recent work suggesting that IDS preference measured in the laboratory has low test-retest reliability.

We investigated syntactic priming in German children to explore crosslinguistic evidence for implicit learning accounts of language production and acquisition. Adult descriptions confirmed that German speakers (N=27) preferred to spontaneously produce active versus passive transitive and DO versus PO dative forms. We tested whether German-speaking children (N=29, Mage=5.3, 15 girls/14 boys) could be primed to produce these dispreferred forms and whether such priming effects would persist across a target phase. Children first heard a block of priming sentences and then described a block of target pictures. They demonstrated significant priming effects for passive and PO dative structures, and these priming effects did not differ between the first and second halves of the block of target trials. These patterns of German child language production are consistent with implicit learning accounts of syntactic priming.

Using archival data from 106 children with and without DLD who spoke two dialects of English, we examined the independent contributions of vocabulary, morphological ability, phonological short term memory (pSTM), and verbal working memory (WM) to exact sentence recall, ungrammatical repetition, and incorrect tense production. For exact repetitions on simpler sentences, performance of the DLD group was predicted by morphological ability, pSTM and WM, while that of the TD group was predicted by vocabulary and sometimes pSTM. On complex sentences, performance of the DLD group was predicted by morphological ability, and the TD group was predicted by pSTM and WM. For ungrammatical repetitions and incorrect tense, morphological ability was a factor for both groups, with WM also affecting the DLD group for ungrammatical production. Thus, sentence recall taxes multiple resources, with more and different factors being taxed at lower levels of complexity for children with DLD than those without.

This paper engages longstanding questions regarding how children acquire morphology in polysynthetic languages. It examines the roles of frequency, perceptual salience, and semantic complexity for morphemes in the acquisition of Northern East Cree possessive inflection, where prefixes and suffixes interact to encode possessors. Two studies analyze naturalistic video recordings of one adult and two children. Study 1 describes the frequency, salience, and complexity of possessor-encoding morphemes in the input. Study 2 traces the acquisition of these morphemes in child speech. Results indicate the acquisition of possessor inflection involves a combination of factors whose influences shift over time. Perceptual salience plays a key role in early noun production, but frequency later corresponds more clearly to acquisitional order for high-frequency morphemes. Complexity is hard to isolate from frequency, although neither factor clearly determines acquisitional order for low-frequency morphemes. The paper concludes by considering implications for science and potential applications for Cree communities.

Six-month-olds infer object size based on pitch: they map high-pitched vowels onto smaller objects and low-pitched vowels onto larger objects (Peña et al., 2011). The ‘sound symbolism bootstrapping hypothesis’ (Imai & Kita, 2014) proposes that this may support understanding of word-meaning correspondences; by drawing on iconic pairings between linguistic cues and corresponding referents (e.g., higher pitch for smaller objects), infants develop understanding of word-referent associations. Here we analyse mother-child interactions, testing whether sound-symbolic pitch-size correspondences occur in infant-directed speech. 40 dyads engaged in (semi-)naturalistic interaction around picture books containing images of toys of varying sizes. We compare mothers’ pitch when referring to small versus large toys, analysing i) actual size (bigger vs. smaller toys); ii) relative toy size congruence (i.e., congruent vs. incongruent with real-world expectation); and iii) transparency of the test paradigm as regards its focus on size contrastiveness (non-transparent, moderately transparent, highly transparent) to observe the nuances of size sound symbolism in infant-directed speech.

Late talkers (LTs) exhibit delayed vocabulary development, which might stem from a lack of a typical word learning strategy to generalise object labels by shape, called the ‘shape bias’. We investigated whether LTs can acquire a shape bias and whether this accelerates vocabulary learning. Fourteen LTs were randomly allocated to either a shape training group (Mage = 2.76 years, 6 males), which was taught that objects similar in shape have the same name, or a control group (Mage = 2.61 years, 4 males), which was taught real words without any focus on object shape. After seven training sessions, children in the shape training group generalised trained labels by shape (d = 1.28), but not unfamiliar labels. Children in the control group extended all labels randomly. Training did not affect expressive vocabulary.

Vowel-initial glottalization constitutes a cue to prosodic prominence, realized on a strength continuum from creaky phonation to complete glottal stops. While there is considerable research on children’s early utilization of acoustic cues for stress marking, less is understood about the specific implementation of vowel-initial glottalization in American English. Eight sequences of function + novel words were elicited from groups of 5-to-8-year-olds, 8-to-11-year-olds, and adults. Children exhibit a similar rate of prevocalic glottalization to adults but differ in its phonetic implementation, producing a higher rate of glottal stops compared to creaky phonation with respect to adults.

Idioms play an important role in language; however, little research has examined idioms in children’s natural language settings. This study explored idioms usage in maternal talk during mother-child shared book reading and its relation to children’s vocabulary development. Thirty-three Chinese children in Norway (aged 3;0–5;5) and their mothers participated. We observed shared reading at the onset of the study and assessed children’s receptive and expressive vocabulary in Chinese three times across one year. Results demonstrated that mothers used an average of 1.8 idioms and explained one-third of the idioms. Maternal idiom usage was correlated with their talk amount and lexical diversity. Individual growth modeling revealed that the number of idioms mothers used predicted the growth of children’s receptive vocabulary in Chinese. We speculate that idiom usage could be an effective and understudied marker of parental linguistic sophistication. This study underscores the importance of idiom exposure in children’s language environment.

This longitudinal study investigated modifications in lexical tones and intonation in Cantonese infant-directed speech (IDS) to children aged 15 and 23 months. The results showed that to children at both ages, mothers increased intonational pitch height and pitch variability across utterances, and produced lexical tones with generally larger tonal space and greater intra-talker tone variation within categories in IDS compared to adult-directed speech. No significant changes were found in either lexical tones or intonation in IDS between the two ages. In addition, positive correlations were found between the degree of age-related changes in tonal space and intonational exaggerations in IDS as children grow older. The findings were discussed with a focus on the co-occurrence of an increase in tone variation along with tonal space expansion, the age-related changes in lexical tones and intonation, and the associations between the lexical and prosodic pitch modifications.

Caregiver-child interactions are commonly used to examine children’s language learning environment. However, few studies consider interaction configurations beyond dyadic interactions or explore the conceptual complexity of caregiver talk. Thus, we examined if the complexity of a caregiver’s opportunities to respond (OTR) varied when sampled across three interaction configurations. Our study included twelve preschool-aged children with Down syndrome and both of their biological parents. Our preliminary findings suggest no differences in mothers’ and fathers’ frequency of OTRs across complexity levels during dyadic interactions. However, caregivers produced fewer OTRs across complexity levels during family choice than dyadic interactions.

This study investigates the changes in the Spanish lexical and grammatical skills of 26 Spanish–English dual language learners during their first year of preschool. We also explore the impact of age, gender, and maternal cultural orientation on children’s language outcomes over time. The results show that, despite one year of English-only instruction, the children’s Spanish productions became more intelligible, lexically diverse, and grammatical between 3;7 and 4;7. However, Spanish productions were mostly limited to sentence fragments and contained errors in grammatical gender, verb morphology, object clitic pronouns, and prepositions. Girls had an advantage over boys, as attested by the higher lexical diversity, mean length of utterance, and grammaticality of their Spanish productions. Both maternal enculturation and acculturation predicted the grammaticality of children’s utterances, suggesting that mothers with high levels of orientation to both Latinx and American culture may be the most successful at promoting Spanish in the United States.

We investigated whether individuals with Williams Syndrome (WS) produce language with a bias towards statistical properties of word combinations rather than grammatical rules, resulting in an overuse of holistically stored, familiar phrases. We analysed continuous speech samples from English children with WS (n = 12), typically developing (TD) controls matched on chronological age (n = 15) and TD controls matched on language age (n = 14). Alongside word count, utterance length, grammatical complexity, and morphosyntactic errors, we measured familiarity of expressions by computing collocation strength of each word combination. The WS group produced stronger collocations than both control groups. Moreover, the WS group produced fewer complex sentences, shorter utterances, and more frequent function words than chronological-age matched controls. Language in WS may appear more typical than it is because familiar, holistically processed expressions mask grammatical and other difficulties.

English-speaking autistic children use the hesitation marker um less often than non-autistic children but use uh at a similar rate. It is unclear why this is the case. We employed a sample of Dutch-speaking children from the Preschool Brain Imaging and Behavior Project to examine hesitation markers in autistic and non-autistic preschoolers with the aim to 1) make a crosslinguistic comparison of hesitation marker usage and 2) examine hypotheses regarding the underlying linguistic mechanisms of hesitation markers: the symptom hypothesis and the signal hypothesis. We found initial group differences in all hesitation markers but these results were rendered insignificant after controlling for age, sex and nonverbal cognition. We found significant correlations between hesitation marker usage and expressive and receptive language, but not autism traits. Lastly, we show interesting cross-linguistic differences in hesitation marker usage between Dutch-speaking participants and previously described English-speaking participants, such as a preference for um over uh.