We investigated how bilinguals choose words in a narrative task, contrasting the possibilities of a developmental delay vs. compensatory strategies. To characterize a developmental delay, we compared younger (three to five years) and older (seven to ten years) children's lexicalization of target words (Study 1). The younger children told shorter stories, omitting many of the target concepts. To characterize compensatory strategies, we compared late second language learning adults to (seven- to ten-year-old) monolingual children (Study 2). The adults often lexicalized the target concepts even when not producing the target words. Finally, we compared French–English bilingual children with French and English monolinguals, all seven to ten years old (Study 3). The bilinguals produced fewer target words than the monolinguals. However, when not producing the target words, the bilinguals often lexicalized the concepts, sharing more in common with the adults (Study 2) in their use of compensatory strategies than with the younger children (Study 1). This interpretation was further corroborated by comparisons across studies (Study 4).

The present study analyzes the effect of age and amount of input in the acquisition of European Portuguese as a heritage language. An elicited production task centred on mood choice in complement clauses was applied to a group of fifty bilingual children (six- to sixteen-year-olds) who are acquiring Portuguese as a minority language in a German dominant environment. The results show a significant effect of the age at testing and the amount of input in the acquisition of the subjunctive. In general, acquisition is delayed with respect to monolinguals, even though higher convergence with the monolingual grammar is observed after twelve years of age. Results also reveal that children with more exposure to the heritage language at home show faster acquisition than children from mixed households: the eight- to nine-year-old age boundary seems relevant for those speakers with more exposure, and the twelve- to thirteen-year-old age boundary for those with less exposure.

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.

Studies examining age of onset (AoO) effects in childhood bilingualism have provided mixed results as to whether early sequential bilingual children (eL2) differ from simultaneous bilingual children (2L1) and L2 children on the acquisition of morphosyntax. Differences between the three groups have been attributed to other factors such as length of exposure (LoE), language abilities, and the phenomenon to be acquired. The present study investigates whether four- to five-year-old German-speaking eL2 children differ from 2L1 children on the acquisition of wh-questions, and whether these differences can be explained by AoO, LoE, and/or knowledge of case marking. The 2L1 children outperformed the eL2 children in terms of accuracy; however, both bilingual groups exhibited similar error patterns. This suggests that 2L1 and eL2 bilingual children are sensitive to the same morphosyntactic cues, when comprehending wh-questions. Finally, children's performance on the different types of wh-questions was explained by a combination of knowledge of case marking, LoE, and AoO.

In this study, age of onset (AoO) was investigated in five- and six-year-old bilingual Frisian–Dutch children. AoO to Dutch ranged between zero and four and had a positive effect on Dutch receptive vocabulary size, but hardly influenced the children's accurate use of Dutch inflection. The influence of AoO on vocabulary was more prominent than the influence of exposure. Regarding inflection, the reverse was found. Accuracy at using Frisian inflection emerged as a significant predictor; this transfer effect was modulated by lexical overlap between the two languages. This study shows that ‘the sooner the better’ does not necessarily hold for language development. In fact, for the correct use of inflection, it does not matter whether children start at age zero or four. For rapidly learning words in a new language it may be helpful to first build a substantial vocabulary in the first language before learning a new language.

This study evaluates the effects of Age of Exposure to English (AoEE) and Current Input/Output on language performance in a cross-sectional sample of Spanish–English bilingual children. First- (N = 586) and third-graders (N = 298) who spanned a wide range of bilingual language experience participated. Parents and teachers provided information about English and Spanish language use. Short tests of semantic and morphosyntactic development in Spanish and English were used to quantify children's knowledge of each language. There were significant interactions between AoEE and Current Input/Output for children at third grade in English and in both grades for Spanish. In English, the relationship between AoEE and language scores were linear for first- and third-graders. In Spanish a nonlinear relationship was observed. We discuss how much of the variance was accounted for by AoEE and Current Input/Output.

This paper explores whether there is evidence for age and/or input effects in child L2 acquisition across three different linguistic domains, namely morphosyntax, vocabulary, and syntax–semantics. More specifically, it compares data from English-speaking children whose age of onset to L2 Dutch was between one and three years with data from children whose age of onset was between four and seven years in their acquisition of verb morphology, verb placement, vocabulary, and direct object scrambling. The main findings were that there were no significant differences between the two groups in any of these areas and, with the exception of scrambling, current amount of exposure was the only factor significantly related to children's scores. The paper discusses the theoretical significance of these findings with respect to the role of input in the language acquisition process and the claim that there is a critical period ending within (early) childhood.

Children are thought to learn second languages (L2s) using primarily implicit mechanisms, in contrast to adults, who primarily rely on explicit language learning. This difference is usually attributed to cognitive maturation, but adults also receive more explicit instruction than children, which may influence their learning strategies. This study crosses instruction condition with age, teaching forty children aged 5;3 to 7;11 and forty adults an artificial mini-language under implicit or explicit training conditions. Participants produced novel sentences and judged sentence grammaticality equally well in either condition, but both children and adults in the explicit training condition developed greater awareness of the mini-language's structures – and greater awareness was associated with better performance for both age groups. Results show that explicit instruction affects children and adults in the same way, supporting the hypothesis that age differences in implicit vs. explicit L2 learning are not exclusively caused by maturation, but also influenced by instruction.

This study examined accuracy in production and grammaticality judgements of verb morphology by eighteen Chinese-speaking children learning English as a second language (L2) followed longitudinally from four to six years of exposure to English, and who began to learn English at age 4;2. Children's growth in accuracy with verb morphology reached a plateau by six years, where 11/18 children did not display native-speaker levels of accuracy for one or more morphemes. Variation in children's accuracy with verb morphology was predicted by their English vocabulary size and verbal short-term memories primarily, and quality and quantity of English input at home secondarily. This study shows that even very young L2 learners might not all catch up to native speakers in this time frame and that non-age factors play a role in determining individual variation in child L2 learners’ long-term outcomes with English morphology.

We report a longitudinal comprehension study of (long) passive constructions in two native-Spanish child groups differing by age of initial exposure to L2 English (young group: 3;0–4;0; older group: 6;0–7;0), where amount of input, L2 exposure environment, and socioeconomic status are controlled. Data from a forced-choice task show that both groups comprehend active sentences, not passives, initially (after 3·6 years of exposure). One year later, both groups improve, but only the older group reaches ceiling on both actives and passives. Two years from initial testing, the younger group catches up. Input alone cannot explain why the younger group takes five years to accomplish what the older group does in four. We claim that some properties take longer to acquire at certain ages because language development is partially constrained by general cognitive and linguistic development (e.g. de Villiers, 2007; Long & Rothman, 2014; Paradis, 2008, 2010, 2011; Tsimpli, 2014).

Production studies show that both Russian-speaking children with specific language impairment (SLI) and bilingual children for whom Russian is a non-dominant language have difficulty distinguishing between the near-synonymous connectives i ‘and’ and a ‘and/but’. I is a preferred connective when reference is maintained, whereas a is normally used for reference shift. We report an eye-tracking experiment comparing connective processing by Russian-speaking monolinguals with typical language development (TLD) with that of Russian–Dutch bilinguals and Russian-speaking monolinguals with SLI (age 5–6). The results demonstrate that the processing profiles of monolinguals with TLD and bilinguals are similar: both groups use connective semantics immediately for predicting further discourse. In contrast, children with SLI do not show sensitivity to these semantic differences. Despite similar production profiles, bilinguals and monolinguals with SLI are clearly different in connective processing. We discuss the implications of these results for the possible causes of the errors in the two populations.

Past research suggests that bilingualism positively affects children's performance in false belief tasks. However, researchers have yet to fully explore factors that are related to better performance in these tasks within bilingual groups. The current study includes an assessment of proficiency in both languages (which was lacking in past work) and investigates the relationship between proficiency and performance in a variety of mental state tasks (not just false belief). Furthermore, it explores whether the relationship between language proficiency and performance in mental state tasks differs between bilingual and monolingual groups. Twenty-six Spanish–English bilingual and twenty-six English monolingual preschool-age children completed seven mental state tasks. Findings provide evidence that high proficiency in English is related to better performance in mental state tasks for monolinguals. In contrast, high proficiency in both English and Spanish is related to better performance in mental state tasks for bilinguals.

The present study examined early vocabulary development in fifty-nine French monolingual and fifty French–English bilingual infants (1;4–1;6). Vocabulary comprehension was assessed using both parental report (MacArthur-Bates Communicative Development Inventory; CDI) and the Computerized Comprehension Task (CCT). When assessing receptive vocabulary development using parental report, the bilinguals knew more words in their L1 versus their L2. However, young bilinguals were as accurate in L1 as they were in L2 on the CCT, and exhibited no difference in speed of word comprehension across languages. The proportion of translation equivalents in comprehension varied widely within this sample of young bilinguals and was linked to both measures of vocabulary size but not to speed of word retrieval or exposure to L2. Interestingly, the monolinguals outperformed the bilinguals with respect to accuracy but not reaction time in their L1 and L2. These results highlight the importance of using multiple measures to assess early vocabulary development.