Agreement is a morphosyntactic dependency which is sensitive to the hierarchical structure of the clause and is constrained by the structural distance that separates the elements involved in this relation. In this paper we present two experiments, providing new evidence that Italian-speaking children with Developmental Language Disorder (DLD), as well as Typically Developing (TD) children, are sensitive to the same hierarchical and locality factors that characterise agreement in adult grammars. This sensitivity holds even though DLD children show accrued difficulties in more complex agreement configurations. In the first experiment, a forced-choice task was used to establish whether children are more affected in the computation of S-V agreement when an element intervenes hierarchically or linearly in the agreement relation: DLD children are more subject to attraction errors when the attractor intervenes hierarchically, indicating that DLD children discriminate between hierarchical and linear configurations. The second experiment, also conducted through a forced-choice task, shows that the computation of agreement in DLD children is more ‘fragile’ than in TD children (and also in children with a primary impairment in the phonological domain), in that it is more sensitive to the factors of complexity identified in Moscati and Rizzi's (2014) typology of agreement configurations. To capture the agreement pattern found in DLD children, we put forth a novel hypothesis: the Fragile Computation of Agreement Hypothesis. Its main tenet is that DLD children make use of the same grammatical operations employed by their peers, as demonstrated in Experiment 1, but difficulties increase as a function of the complexity of the agreement configuration.

Linguistic expressions of locative spatial relations in sign languages are mostly visually motivated representations of space involving mapping of entities and spatial relations between them onto the hands and the signing space. These are also morphologically complex forms. It is debated whether modality-specific aspects of spatial expressions modulate spatial language development differently in signing compared to speaking children. In a picture description task, we compared the use of locative expressions for containment, support, and occlusion relations by deaf children acquiring Turkish Sign Language and hearing children acquiring Turkish (age 3;5–9;11). Unlike previous reports suggesting a boosting effect of iconicity, and/or a hindering effect of morphological complexity of the locative forms in sign languages, our results show similar developmental patterns for signing and speaking children's acquisition of these forms. Our results suggest the primacy of cognitive development guiding the acquisition of locative expressions by speaking and signing children.

This study investigates the role of parental input quality on the acquisition of Greek as a heritage language in Western Canada. Focusing on subject use, we tested four groups of Greek speakers: monolingual children, heritage children, and the parents of each one of those groups. Participants completed an elicited production task designed to elicit subject placement in wide focus and embedded interrogative contexts, where postverbal subjects are preferred/required in the monolingual variety. Results gave rise to two main conclusions: first, the parental input received by heritage children may be qualitatively different from the parental input received by monolingual children, in that it contains a higher rate of deviant preverbal subjects. Second, parental input quality in addition to quantity may affect the outcome of heritage language acquisition, in that children producing a higher rate of preverbal subjects had parents whose Greek input was not only quantitatively reduced, but also richer in preverbal subjects.

This study examined early Hebrew verb acquisition, highlighting CDS–CS relations across inflectional and derivational verb learning. It was carried out on a corpus of longitudinal dense dyadic interactions of two Hebrew-speaking toddlers aged 1;8–2;2 and their parents. Findings revealed correlated patterns within and between CDS and CS corpora in terms of verbs, structural root categories, and their components (roots, binyan conjugations, and derivational verb families), and clear relations between lexical-derivational development and inflectional growth in input–output relations, measured by MSP. It also showed that both corpora had few, yet highly semantically coherent, derivational families. Lexical learning in Hebrew was shown to be morphologically oriented, with both inflectional and derivational learning supporting and being supported by the development of the verb lexicon. These findings support findings in the general literature regarding the close relationship between parental input and child speech, and the affinity between lexical and grammatical growth.

We investigated whether Tagalog-speaking children incrementally interpret the first noun as the agent, even if verbal and nominal markers for assigning thematic roles are given early in Tagalog sentences. We asked five- and seven-year-old children and adult controls to select which of two pictures of reversible actions matched the sentence they heard, while their looks to the pictures were tracked. Accuracy and eye-tracking data showed that agent-initial sentences were easier to comprehend than patient-initial sentences, but the effect of word order was modulated by voice. Moreover, our eye-tracking data provided evidence that, by the first noun phrase, seven-year-old children looked more to the target in the agent-initial compared to the patient-initial conditions, but this word order advantage was no longer observed by the second noun phrase. The findings support language processing and acquisition models which emphasize the role of frequency in developing heuristic strategies (e.g., Chang, Dell, & Bock, 2006).

This study evaluates the ability of different measures of socioeconomic status (SES) to predict lexical outcomes for preschoolers raised in a context of nationwide bilingualism. The participants were 58 children aged 3;11–4;3 from Maltese-dominant homes who attended state preschools. Receptive picture name judgement and picture naming, in Maltese and English, were employed to measure receptive and expressive lexical abilities, respectively. Lexical outcomes for four individual SES variables and a single composite SES measure were similar but not directly interchangeable. The composite SES variable emerged as most strongly predictive of children's lexical performance. Receptive judgement of phonological accuracy improved similarly in both languages with higher composite SES. Naming skills increased significantly in English but not in Maltese, suggesting differences in English input related to parental SES. A focus on SES in relation to lexical skills in two majority languages is novel and adds to current understanding of normative bilingual acquisition.

This study examines the influence of bilingual status, language-internal (complexity of L1 phonology), language-external (dominance), and lexical (L2 vocabulary score) factors on phonological production in French-speaking monolingual (n = 37) and bilingual children (n = 64) aged three to six years. Children participated in an object and picture naming task which tested different phonological features. The bilinguals’ first languages were coded in terms of the complexity of these phonological features. In addition, the parents completed a questionnaire on their child's language dominance and the children were administered a vocabulary test in their L2. Results indicated that vocabulary was the principal predictor of phonological accuracy across both age groups. Apparent monolingual–bilingual differences and dominance effects could largely be explained by vocabulary scores: children who scored better on a vocabulary test obtained superior phonological accuracy. Language-internal effects were minimal and marginally influenced vowel accuracy only.

This study explores how young children infer nuances in epistemic modality through prosody. A forced-choice task was used, testing children's (ages three to seven) comprehension of the might/will distinction (modal condition) as well their ability to modulate the strength of might through two prosodic tunes (prosody condition). Positive and negative valence conditions were included. Younger children were shown to start off performing above chance for the modal condition, and at around chance for the prosody condition, but after age four performance on the prosody condition quickly improved. For both modal verbs and prosody, children performed significantly better when valence was positive. By age seven, children performed at ceiling for all conditions. Qualitative analysis of children's justifications for prosody responses showed metalinguistic awareness of prosodic meaning as early as age four, with the ability to relate prosody to epistemic modal meaning becoming quite common by age seven.

Irish is a rapidly changing minority language spoken as the main community language in some areas of the officially Irish-speaking Gaeltacht regions in Ireland. We analyse narratives from 17 parent–child dyads, living in one such area. All children, aged 3–6;4, had high exposure to the local variety of Irish. The input quality was measured by specifying consistency and accuracy of use of morphosyntactic forms in parental narratives directed to their children. The same morphosyntactic forms were analysed in narrative retell by the children. The children produced with high accuracy those forms that the parents used consistently and accurately. For the forms where parents’ usage was inconsistent, large variation in the children's usage was observed. The findings suggest that consistency and accuracy in the use of morphosyntactic forms in the parental language is an important factor in language acquisition; however, its influence might be confounded by other factors.

This paper provides an overview of the features of caregiver input that facilitate language learning across early childhood. We discuss three dimensions of input quality: interactive, linguistic, and conceptual. All three types of input features have been shown to predict children's language learning, though perhaps through somewhat different mechanisms. We argue that input best designed to promote language learning is interactionally supportive, linguistically adapted, and conceptually challenging for the child's age/level. Furthermore, input features interact across dimensions to promote learning. Some but not all qualities of input vary based on parent socioeconomic status, language, or culture, and contexts such as book-reading or pretend play generate uniquely facilitative input features. The review confirms that we know a great deal about the role of input quality in promoting children's development, but that there is much more to learn. Future research should examine input features across the boundaries of the dimensions distinguished here.

Previous research suggests that increased second language (L2) input at home may not support L2 acquisition in children from migrant backgrounds. In drawing this conclusion, existing work has largely aggregated across family members. This study contrasts the effect of L2 input from older siblings with that from mothers. Participants were 113 child L2 learners of English (mean age = 5;10 [range 4;10–7;2]; mean exposure to L2 in school = 16.7 months [range 2–48 months]). All children had at least one older sibling. Using hierarchical linear regression modelling with controls for age, non-verbal reasoning and phonological short-term memory, we found that greater L2 input from siblings – but not mothers – was associated with stronger L2 abilities in narrative macrostructure, inflectional morphology, and vocabulary. Increased cumulative exposure to the L2 at school and greater maternal L2 fluency were also positively related to children's L2 inflectional morphology and vocabulary scores.

Previous research has shown that in a minority–majority language context, the quantity of language input at home is more important for the development of the minority language than for the development of the majority language. In the current study, we examined whether the same holds true for the frequency of specific language activities at home. In a group of five- and six-year-old Frisian–Dutch bilingual children (n = 120), we investigated to what extent vocabulary and morphology knowledge were predicted by reading activities, watching TV, and story-telling activities in both languages. The results showed that reading in Frisian predicted both Frisian vocabulary and morphology, while reading in Dutch only predicted Dutch vocabulary. This shows that reading at home is most important for the development of the minority language. This especially holds true for the acquisition of Frisian morphology, a domain that is known to be vulnerable in language acquisition.

Mentalising has long been suggested to play an important role in irony interpretation. We hypothesised that another important cognitive underpinning of irony interpretation is likely to be children's capacity for mental set switching – the ability to switch flexibly between different approaches to the same task. We experimentally manipulated mentalising and set switching to investigate their effects on the ability of 7-year-olds to determine if an utterance is intended ironically or literally. The component of mentalising examined was whether the speaker and listener shared requisite knowledge.

We developed a paradigm in which children had to select how a listener might reply, depending on whether the listener shared knowledge needed to interpret the utterance as ironic. Our manipulation of requisite set switching found null results. However, we are the first to show experimentally that children as young as seven years use mentalising to determine whether an utterance is intended ironically or literally.

This study examined the linguistic and individual-level factors that render case marking a vulnerable domain in English-dominant Greek heritage children. We also investigated whether heritage language (HL) children can use case-marking cues to interpret (non-)canonical sentences in Greek similarly to their monolingual peers. A group of six- to twelve-year-old Greek heritage children in New York City and a control group of age-matched monolingual children living in Greece participated in a production and a picture verification task targeting case marking and (non-)canonical word order in Greek. HL children produced syncretic inflectional errors, also found in preschool monolingual children. In the comprehension task, HL children showed variable performance on the non-canonical OVS but ceiling performance on the SVO conditions, which suggests influence from English. Linguistic factors such as case transparency affected comprehension, whereas child-level factors such as proficiency and degree of (early) use of Greek influenced performance on both modalities.

Within developmental psychology, pointing gestures have received a great deal of attention, while ostensive gestures have been overlooked in terms of their emergence and intentionality. In a longitudinal and micro-genetic study with six children at 9, 11, and 13 months of age, we codified gesture production of children within second-by-second data frames. We identified 480 instances of gestures and categorised whether they were of ostensive, ostensive–indexical, or indexical nature. We specified the communicative function of each gesture by analysing the object involved and their circumstances of production. Data analysis include frequencies, binomial tests, proportion comparisons, and repeated measures ANOVA. We identified a phatic function in other-directed gestures, as well as exploratory and private functions in self-directed gestures. This has important implications for child development since ostensive gestures are easier to produce and to understand than pointing. The consideration of objects would be essential for defining the communicative function of gestures.

Infant-directed speech (IDS) is a specific register that adults use to address infants, and it is characterised by prosodic exaggeration and lexical and syntactic simplification. Several authors have underlined that this simplified speech becomes more complex according to the infant's age. However, there is a lack of studies on lexical and syntactic modifications in Italian IDS during the first year of an infant's life. In the present study, 80 mother–infant dyads were longitudinally observed at 3, 6, 9, and 12 months during free-play interactions. Maternal vocal productions were subsequently coded. The results show an overall low lexical variability and syntactic complexity that identify speech to infants as a simplified register; however, the high occurrence of complex items and well-structured utterances suggests that IDS is not simple speech. Moreover, maternal IDS becomes more complex over time, but not linearly, with a maximum simplification in the second half of the first year.

This study investigated how Korean toddlers’ perception of stop categories develops in the acoustic dimensions of VOT and F0. To examine the developmental trajectory of VOT and F0 in toddlers’ perceptual space, a perceptual identification test with natural and synthesized sound stimuli was conducted with 58 Korean monolingual children (aged 2–4 years). The results revealed that toddlers’ perceptual mapping functions on VOT mainly in the high-pitch environment, resulting in more successful perceptual accuracy in fortis or aspirated stops than in lenis stops. F0 development is correlated with the perceptual distinction of lenis from aspirated stops, but no consistent categorical perception for F0 was found before four years of age. The findings suggest that multi-parametric control in perceptual development guides an acquisition ordering of Korean stop phonemes and that tonal development is significantly related to the acquisition of Korean phonemic contrasts.

To code-switch or not to code-switch? This is a dilemma for many bilingual language teachers. In this study, the influence of teachers’ CS on bilingual children's language and cognitive development is explored within heritage language (HL) classes in Singapore. Specifically, the relationship between children's language output, vocabulary development, and cognitive flexibility to teachers’ classroom CS behavior, is examined within 20 preschool HL classrooms (10 Mandarin, 6 Malay, and 4 Tamil). Teachers’ and children's utterances were recorded, transcribed, and analyzed for CS frequency and type (i.e., inter-sentential, intra-sentential). 173 students were assessed with receptive vocabulary and dimensional card sort tasks, and their vocabulary and cognitive switching scores assessed using correlational and mixed effects analyses. Results show that inter-sentential and intra-sentential CS frequency is positively and significantly related to children's intra-sentential CS frequency. Overall, findings revealed that teachers code-switched habitually more often than for instructional purposes. Neither inter-sentential nor intra-sentential CS was significantly related to children's development in HL vocabulary, and intra-sentential CS was found to positively and significantly relate to children's growth in cognitive flexibility. These findings reveal the multi-faceted impact of teacher's CS on children's early development.