Children's vocabulary ability at school entry is highly variable and predictive of later language and literacy outcomes. Sleep is potentially useful in understanding and explaining that variability, with sleep patterns being predictive of global trajectories of language acquisition. Here, we looked to replicate and extend these findings. Data from 354 children (without English as an additional language) in the Born in Bradford study were analysed, describing the mean intercepts and linear trends in parent-reported day-time and night-time sleep duration over five time points between 6 and 36 months-of-age. The mean difference between night-time and day-time sleep was predictive of receptive vocabulary at age five, with more night-time sleep relative to day-time sleep predicting better language. An exploratory analysis suggested that socioeconomic status was predictive of vocabulary outcomes, with sleep patterns partially mediating this relationship. We suggest that the consolidation of sleep patterns acts as a driver of early language development.

The Yucatec Maya language has a highly complex deictic system with interesting typological differences that in addition to demonstratives and locative adverbs also includes ostensive evidentials and modal adverbs. Given that deictic words are among the first that children produce, the aim of this study is to identify the early acquisition that Yucatec Mayan children follow to map out each deictic form. Deictic words taken from spontaneous, longitudinal, transversal corpora and Gaskins's (1990) field work annotations were labeled and analyzed. The results show that children begin by uttering protoforms mapped with prototypical functions of locative and modal adverbs, but the functions of both demonstratives and ostensive evidentials are expressed mostly with the same protoform, which is similar to the deictic organizations of other languages. When children become productive, they overextend functions, which demonstrates a reanalysis of the system before acquisition is complete.

It remains unclear whether pragmatic language skills and core language skills (grammar and vocabulary) are distinct language domains. The present work aimed to tease apart these domains using a novel online assessment battery administered to almost 400 children aged 7 to 13 years. Confirmatory factor analysis indicated that pragmatic and core language domains could be measured separately, but that both domains were highly related (r = .79). However, zero-order correlations between pragmatic tests were quite small, indicating that task-specific skills played an important role in performance, and follow-up exploratory factor analysis suggested that pragmatics might be best understood as a family of skills rather than a domain. This means that these different pragmatic skills may have different cognitive underpinnings and also need to be assessed separately. However, our overall results supported the idea that pragmatic and core aspects of language are closely related during development, with one area scaffolding development in the other.

We test the comprehension of transitive sentences in very young learners of Mandarin Chinese using a combination of the weird word order paradigm with the use of pseudo-verbs and the preferential looking paradigm, replicating the experiment of Franck et al. (2013) on French. Seventeen typically-developing Mandarin infants (mean age: 17.4 months) participated and the same experiment was conducted with eighteen adults. The results show that hearing well-formed NP-V-NP sentences triggered infants to fixate more on a transitive scene than on a reflexive scene. In contrast, when they heard deviant NP-NP-V sequences, no such preference pattern was found, a performance pattern that is adult-like. This is at variance with some of the results from Candan et al. (2012), who only found evidence for canonical word order comprehension at almost age 3 when considering fixation time. Furthermore, within the age range tested, performance showed no effect of age or vocabulary size.

The current study explores variation in phonemic representation among Spanish–English dual language learners (DLLs, n = 60) who were dominant in English or in Spanish. Children were given a phonetic discrimination task with speech sounds that: 1) occur in English and Spanish, 2) are exclusive to English, and 3) are exclusive to Russian, during Fall (age m = 57 months) and Spring (age m = 62 months, n = 42). In Fall, English-dominant DLLs discriminated more accurately than Spanish-dominant DLLs between English-Spanish phones and English-exclusive phones. Both groups discriminated Russian phones at or close to chance. In Spring, however, groups no longer differed in discriminating English-exclusive phones and both groups discriminated Russian phones above chance. Additionally, joint English-Spanish and English-exclusive phonetic discrimination predicted children's phonological awareness in both groups. Results demonstrate plasticity in early childhood through diverse language exposure and suggest that phonemic representation begins to emerge driven by lexical restructuring.

Many children grow up hearing multiple languages, learning words in each. How does the number of languages being learned affect multilinguals’ vocabulary development? In a pre-registered study, we compared productive vocabularies of bilingual (n = 170) and trilingual (n = 20) toddlers aged 17–33 months growing up in a bilingual community where both French and English are spoken. We hypothesized that because trilinguals have reduced input in French and English due to time spent hearing their third language, they would have smaller French–English vocabulary sizes than bilinguals. Trilinguals produced on average 2/3 of the number of words in these languages that bilinguals did: however, this difference was not statistically robust due to large levels of variability. Follow-up analyses did, however, indicate a relationship between input quantity and vocabulary size. Our results indicate that similar factors contribute to vocabulary development across toddlers regardless of the number of languages being acquired.

Young children struggle more with mapping novel words onto relational referents (e.g., verbs) compared to non-relational referents (e.g., nouns). We present further evidence for this notion by investigating children's extensions of noun-noun compounds, which map onto combinations of non-relational referents, i.e., objects (e.g., baby and bottle for baby bottle), and relations (e.g., a bottle FOR babies). We tested two- to five-year-olds’ and adults’ generalisations of novel compounds composed of novel (e.g., kig donka) or familiar (e.g., star hat) nouns that were combined by one of two relations (e.g., donka that has a kig attached (=attachment relation) versus donka that stores a kig (=function relation)). Participants chose between a relational (shared relation) and a non-relational (same colour) match. Results showed a developmental shift from encoding non-relational aspects (colour) towards relations of compound referents, supporting the challenge of relational word referents. Also, attachment relations were more frequently encoded than function relations.

Polysemy, or the property of words having multiple meanings, is a prevalent feature of vocabulary. In this study we validated a new measure of polysemy knowledge for children with English as an additional language (EAL) and a first language (EL1) and examined the relationship between polysemy knowledge and age, language status, and reading comprehension. Participants were 112 British children aged 5 to 6 (n = 61) or 8 to 9 years (n = 51), 37% of whom had EAL (n = 41). Participants completed the new measure of knowledge of polysemes, along with other measures of language, literacy and cognitive ability. The new measure was reliable and valid with EAL and EL1 children. Age and language status predicted children's polyseme knowledge. Polyseme knowledge uniquely contributed to reading comprehension after controlling for age, language status, non-verbal intelligence, time reading in English, and breadth of vocabulary. This research underscores the importance of polysemy for children's linguistic development.

Multisyllabic words constitute a large portion of children's vocabulary. However, the relationship between phonological neighborhood density and English multisyllabic word learning is poorly understood. We examine this link in three, four and six year old children using a corpus-based approach. While we were able to replicate the well-accepted positive association between CVC word acquisition and neighborhood density, no similar relationship was found for multisyllabic words, despite testing multiple novel neighborhood measures. This finding raises the intriguing possibility that phonological organization of the mental lexicon may play a fundamentally different role in the acquisition of more complex words.