We designed a parent-directed home-visiting intervention targeting socioeconomic status (SES) disparities in children's early language environments. A randomized controlled trial was used to evaluate whether the intervention improved parents' knowledge of child language development and increased the amount and diversity of parent talk. Twenty-three mother–child dyads (12 experimental, 11 control, aged 1;5–3;0) participated in eight weekly hour-long home-visits. In the experimental group, but not the control group, parent knowledge of language development increased significantly one week and four months after the intervention. In lab-based observations, parent word types and tokens and child word types increased significantly one week, but not four months, post-intervention. In home-based observations, adult word tokens, conversational turn counts, and child vocalization counts increased significantly during the intervention, but not post-intervention. The results demonstrate the malleability of child-directed language behaviors and knowledge of child language development among low-SES parents.

This study examined the vocabulary development of Norwegian second language (L2) learners with Urdu/Punjabi as their first language (L1) at two time-points from kindergarten to primary school, and compared it to the vocabulary development of monolingual Norwegian children. Using path models, the associations between number of picture books in the home, maternal education, and previous L1 and L2 vocabulary on the development of L2 vocabulary breadth and depth were investigated. The results indicate that despite the weaker vocabulary skills of the L2 sample, the growth trajectories of the L2 learners and the monolingual comparison group did not differ. For the L2 learners, we identified both concurrent and longitudinal predictors of vocabulary: the number of books in the home and the time of introduction of the L2 predicted concurrent vocabulary. L1 vocabulary, number of books in the home, and the time of introduction of the L2 predicted vocabulary growth.

Children struggle with the interpretation of pronouns in direct speech (Ann said, “I get a cookie”), but not in indirect speech (Ann said that she gets a cookie) (Köder & Maier, 2016). Yet children's books consistently favor direct over indirect speech (Baker & Freebody, 1989). To reconcile these seemingly contradictory findings, we hypothesize that the poor performance found by Köder and Maier (2016) is due to the information-transmission setting of that experiment, and that a narrative setting facilitates children's processing of direct speech. We tested 42 Dutch children (4;1–7;2) and 20 adults with a modified version of Köder and Maier's referent selection task, where participants interpret speech reports in an interactive story book. Results confirm our hypothesis: children are much better at interpreting pronouns in direct speech in such a narrative setting than they were in an information-transmission setting. This indicates that the pragmatic context of reports affects their processing effort.

In order to understand how language abilities emerge in typically and atypically developing infants and toddlers, it is important to embrace complexity in development. In this paper, we describe evidence that early language development is an experience-dependent process, shaped by diverse, interconnected, interdependent developmental mechanisms, processes, and abilities (e.g. statistical learning, sampling, functional specialization, visual attention, social interaction, motor ability). We also present evidence from our studies on neurodevelopmental disorders (e.g. Down syndrome, fragile X syndrome, Williams syndrome) that variations in these factors significantly contribute to language delay. Finally, we discuss how embracing complexity, which involves integrating data from different domains and levels of description across developmental time, may lead to a better understanding of language development and, critically, lead to more effective interventions for cases when language develops atypically.

Production studies show connective acquisition by age 3;0, but comprehension studies show errors until 9;0 or older. To further investigate this gap, two comprehension tasks were carried out with 78 Dutch children between the ages of 7;0 and 10;1, testing contrastive maar ‘but’ and causal want ‘because’ connectives for comparison. An existing context choice task and a task that tested children's ability to interpret pronouns dependent on the connective were used. Children did well on the context choice task for want ‘because’, but performed far below chance with maar ‘but’. In the pronoun interpretation task the youngest children performed at or near chance with both connectives, but show gradual improvement with age. Task complexity may partially explain the results but in general, they are consistent with previous experiments showing contrastive connective comprehension is acquired very late compared to their correct production. Further, the pronoun interpretation task may give a more accurate picture of understanding.

The MacArthur-Bates Communicative Development Inventories (CDIs) are a widely used family of parent-report instruments for easy and inexpensive data-gathering about early language acquisition. CDI data have been used to explore a variety of theoretically important topics, but, with few exceptions, researchers have had to rely on data collected in their own lab. In this paper, we remedy this issue by presenting Wordbank, a structured database of CDI data combined with a browsable web interface. Wordbank archives CDI data across languages and labs, providing a resource for researchers interested in early language, as well as a platform for novel analyses. The site allows interactive exploration of patterns of vocabulary growth at the level of both individual children and particular words. We also introduce wordbankr, a software package for connecting to the database directly. Together, these tools extend the abilities of students and researchers to explore quantitative trends in vocabulary development.

This longitudinal study assessed three acoustic components of maternal infant-directed speech (IDS) – pitch, affect, and vowel hyperarticulation – in relation to infants’ age and their expressive vocabulary size. These three individual components were measured in IDS addressed to infants at 7, 9, 11, 15, and 19 months (N = 18). All three components were exaggerated at all ages in mothers’ IDS compared to their adult-directed speech. Importantly, the only significant predictor of infants’ expressive vocabulary size at 15 and 19 months was vowel hyperarticulation, but only at 9 months and beyond, not at 7 months, and not pitch or affect at any age. These results set apart vowel hyperarticulation in IDS to infants as the critical IDS component for vocabulary development. Thus IDS, specifically the degree of vowel hyperarticulation therein, is a vehicle by which parents can provide the most optimal speech quality for their infants’ linguistic and communicative development.

Both the input directed to the child, and the child's ability to process that input, are likely to impact the child's language acquisition. We explore how these factors inter-relate by tracking the relationships among: (a) lexical properties of maternal child-directed speech to prelinguistic (7-month-old) infants (N = 121); (b) these infants' abilities to segment lexical targets from conversational child-directed utterances in an experimental paradigm; and (c) the children's vocabulary outcomes at age 2;0. Both repetitiveness in maternal input and the child's speech segmentation skills at age 0;7 predicted language outcomes at 2;0; moreover, while these factors were somewhat inter-related, they each had independent effects on toddler vocabulary skill, and there was no interaction between the two.

This study set out to examine whether shyness, an aversion to novelty and unfamiliar social situations, can affect the processes that underlie early word learning. Twenty-four-month-old children (n =32) were presented with sets of one novel and two familiar objects, and it was found that shyer children were less likely to select a novel object as the referent of a novel label. Furthermore, not-shy children then showed evidence of retaining these novel mappings, but shy children did not. These findings suggest that shy children's aversion to novelty and to the unfamiliar context can impact on their word learning.

Research has shown that observing iconic gestures helps typically developing children (TD) and children with specific language impairment (SLI) learn new words. So far, studies mostly compared word learning with and without gestures. The present study investigated word learning under two gesture conditions in children with and without language impairment. Twenty children with SLI (age four), twenty age-matched TD children, and twenty language-matched TD children were taught words that were presented with either iconic or non-iconic gestures. Results showed that children of all groups benefited more successfully from observing iconic gestures for word learning. The iconic gesture advantage was similar across groups. Thus, observing iconic gestures prompts richer encoding and makes word learning more efficient in TD and language impaired children.