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 environmental context of verbs addressed by adults to young children is claimed to be uninformative regarding the verbs' meaning, yielding the Syntactic Bootstrapping Hypothesis that, for verb learning, full sentences are needed to demonstrate the semantic arguments of verbs. However, reanalysis of Gleitman's (1990) original data regarding input to a blind child revealed the context of single-word parental verbs to be more transparent than that of sentences. We tested the hypothesis that English-speaking children learn their early verbs from parents' single-word utterances. Distribution of single-word transitive verbs produced by a large sample of young children was strongly predicted by the relative token frequency of verbs in parental single-word utterances, but multiword sentences had no predictive value. Analysis of the interactive context showed that objects of verbs are retrievable by pragmatic inference, as is the meaning of the verbs. Single-word input appears optimal for learning an initial vocabulary of verbs.

The present study applies a multidimensional methodological approach to the study of the acquisition of morphosyntax. It focuses on evaluating the degree of productivity of an infrequent subject–verb agreement pattern in the early acquisition of French and considers the explanatory role played by factors such as input frequency, semantic transparency of the agreement markers, and perceptual factors in accounting for comprehension of agreement in number (singular vs. plural) in an experimental setting. Results on a pointing task involving pseudo-verbs demonstrate significant comprehension of both singular and plural agreement in children aged 2;6. The experimental results are shown not to reflect input frequency, input marker reliability on its own, or lexically driven knowledge. We conclude that toddlers have knowledge of subject–verb agreement at age 2;6 which is abstract and productive despite its paucity in the input.

This paper investigates whether three-year-olds are able to process attributive adjectives (e.g., soft pillow) as they hear them and to predict the noun (pillow) on the basis of the adjective meaning (soft). This was investigated in an experiment by means of the Visual World Paradigm. The participants saw two pictures (e.g., a pillow and a book) and heard adjective–noun combinations, where the adjective was either informative (e.g., soft) or uninformative (e.g., new) about the head-noun. The properties described by the target adjectives were not visually apparent. When the adjective was uninformative, the looks at the target increased only upon hearing the noun. When the adjective was informative, however, the looks at the target increased upon hearing the adjective. Three-year-olds were as fast as adult controls in predicting the upcoming noun. We conclude that toddlers process adjective–noun phrases incrementally and can predict the noun based on the prenominal adjective.

The study characterizes developmental trends in early Hebrew clause-combining (CC) by analyzing the interplay between linguistic form and communicative function in different interactional settings. Analysis applied to all utterances produced by three children aged 2;0–3;0 who combined two or more clauses, either self-initiated or on the basis of adult input. Ten types of CC were analyzed for marking by connectives (e.g. the Hebrew equivalents of ‘and’, ‘that’, ‘so’). Four shared consecutive developmental phases emerged: non-marking; partial marking by ‘and’ and ‘that’; use of ‘but’ and ‘because’, favored significantly in interlocutor-supported contexts; marking of adverbial relations and more varied use of še- ‘that’. These CC processes are interpreted as reflecting general properties of language development, in the form of gradually increasing specification of form–function relations under the impact of interlocutor–child interactive support combined with Hebrew-particular typological factors.

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.

The present study investigated children's early use of verb inflection in Japanese by comparing a generativist account, which predicts that the past tense will have a special default-like status for the child during the early stages, with a constructivist input-driven account, which assumes that children's acquisition and use of inflectional forms reflects verb-specific distributional patterns in their input. Analysis of naturalistic data from four Japanese children aged 1;5 to 2;10 showed that there was substantial by-verb variation in the use of inflectional forms from the earliest stages of verb use, and no general preference for past tense forms. Correlational and partial correlational analyses showed that it was possible to predict the proportional frequency with which the child produced verbs in past tense versus other inflectional forms on the basis of differences in the proportional frequency with which the verb occurred in past tense form in the child's input, even after controlling for differences in the rate at which verbs occurred in past tense form in input averaged across the caregivers of the other children in the sample. When taken together, these results count against the idea that the past tense has a special default-like status in early child Japanese, and in favour of a constructivist input-driven account of children's early use of verb inflection.

Constraints on linguistic variation are consistent across adult speakers, yielding probabilistic and systematic patterns. Yet, little is known about the development of such patterns during childhood. This study investigates Spanish subject pronoun expression in naturalistic data from 154 monolingual children in Mexico, divided into four age groups: 6–7, 8–9, 10–11, 12+. Results from logistic regressions examining five predictors of pronoun expression in 6,481 verbs show that children's usage is structured and patterned. The study also suggests a developmental progression: as children get older, they become sensitive to more constraints. I conclude by suggesting that children learn patterns of variation by attuning to distributional tendencies in the input, and that the more frequent the patterns are, the easier they are to detect and learn.

Early spontaneous gesture, specifically deictic gesture, predicts subsequent vocabulary development in typically developing (TD) children. Here, we ask whether deictic gesture plays a similar role in predicting later vocabulary size in children with Down Syndrome (DS), who have been shown to have difficulties in speech production, but strengths in spontaneous gesture and baby sign use. We compared the gestures and baby signs produced by twenty-three children with DS (Mage = 2;6) and twenty-three TD children (Mage = 1;6), in relation to their expressive spoken vocabulary size one year later. Children with DS showed significant deficits in gesture production, particularly for deictic gestures, but strengths in baby sign production, compared to their typically developing peers. More importantly, it was the baby signs produced by children with DS, but not deictic gestures, that predicted their spoken vocabulary size one year later. Our results further highlight the important role baby signs can play in language development in children with developmental disorders.

The ability to compute non-adjacent regularities is key in the acquisition of a new language. In the domain of phonology/phonotactics, sensitivity to non-adjacent regularities between consonants has been found to appear between 7 and 10 months. The present study focuses on the emergence of a posterior–anterior (PA) bias, a regularity involving two non-adjacent vowels. Experiments 1 and 2 show that a preference for PA over AP (anterior–posterior) words emerges between 10 and 13 months in French-learning infants. Control experiments show that this bias cannot be explained by adjacent or positional preferences. The present study demonstrates that infants become sensitive to non-adjacent vocalic distributional regularities between 10 and 13 months, showing the existence of a delay for the acquisition of non-adjacent vocalic regularities compared to equivalent non-adjacent consonantal regularities. These results are consistent with the CV hypothesis, according to which consonants and vowels play different roles at different linguistic levels.

This study investigates the development of metalinguistic skills, particularly ambiguity detection, and whether training accelerates this development for prereaders in kindergarten (5;5–6;6). It is the first to compare homophone detection with lexically ambiguous sentence detection in which the same homophones appear. The experimental group received ambiguity detection training; the control group received vocabulary training. Results showed that there is a spontaneous development of homophone detection abilities at the end of kindergarten, and training may accelerate this trajectory. The development of lexical ambiguity detection is not apparent in kindergarteners. However, explicit training improves this trajectory significantly. The knowledge of both meanings of a homophone is not sufficient to report both meanings of a sentence that contains that homophone. We propose that detecting the dual meanings of an ambiguous sentence involves sentence processing operations and an ability to think flexibly about language that may be enhanced with training.

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.

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).

Fathers’ child-directed speech across two contexts was examined. Father–child dyads from sixty-nine low-income families were videotaped interacting during book reading and toy play when children were 2;0. Fathers used more diverse vocabulary and asked more questions during book reading while their mean length of utterance was longer during toy play. Variation in these specific characteristics of fathers’ speech that differed across contexts was also positively associated with child vocabulary skill measured on the MacArthur-Bates Communicative Development Inventory. Results are discussed in terms of how different contexts elicit specific qualities of child-directed speech that may promote language use and development.

We investigated 16- and 20-month-olds' flexibility in mapping phonotactically illegal words to objects. Using an associative word-learning task, infants were presented with a training phase that either highlighted or did not highlight the referential status of a novel label. Infants were then habituated to two novel objects, each paired with a phonotactically illegal Czech word. When referential cues were provided, 16-, but not 20-month-olds, formed word–object mappings. In the absence of referential cues, infants of both ages failed to map the novel words. These findings illustrate the complex interplay between infants' developing sound system and their word learning abilities.

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 study uses a structural priming technique with young Spanish speakers to test whether exposure to a rare syntactic form in Spanish (fue-passive) would increase the production and comprehension of that form. In Study 1, 14 six-year-old Spanish speakers described pictures of transitive scenes. This baseline study revealed that fue-passives were virtually non-existent in children's spontaneous speech. Using the priming technique in Study 2, an additional 56 Spanish-speaking children were exposed to fue-passive or active picture descriptions; we varied whether children repeated the modeled form. With repetition, production of fue-passives increased past baseline usage. When not asked to repeat, comprehension and production of fue-passives was no different than chance. Results extend the existing literature by experimentally testing input effects on the production and comprehension of infrequently used constructions, further corroborating the relation between input frequency and language skill. Findings are consistent with the view that an implicit learning mechanism guides language learning.

Young children are slow to master conventional intonation patterns in their yes/no questions, which may stem from imperfect understanding of the links between terminal pitch contours and pragmatic intentions. In Experiment 1, five- to ten-year-old children and adults were required to judge utterances as questions or statements on the basis of intonation alone. Children eight years of age or younger performed above chance levels but less accurately than adult listeners. To ascertain whether the verbal content of utterances interfered with young children's attention to the relevant acoustic cues, low-pass filtered versions of the same utterances were presented to children and adults in Experiment 2. Low-pass filtering reduced performance comparably for all age groups, perhaps because such filtering reduced the salience of critical pitch cues. Young children's difficulty in differentiating declarative questions from statements is not attributable to basic perceptual difficulties but rather to absent or unstable intonation categories.

This study is about the role of elicited verbal imitation in toddler word learning. Forty-eight toddlers were taught eight nonwords linked to referents. During training, they were asked to imitate the nonwords. Naming of the referents was tested at three intervals (one minute later [uncued], five minutes, and 1–7 days later [cued]) and recognition at the last two intervals. Receptive vocabulary, nonword repetition, and expressive phonology were assessed. The accuracy of elicited imitation during training predicted naming at one and five minutes, but not 1–7 days later. Neither nonword repetition nor expressive phonology was associated with naming over time but extant vocabulary predicted performance at all time intervals. We hypothesize that elicited imitation facilitates word learning in its earliest stages by supporting encoding of the word form into memory and allowing practice of the articulatory-phonological plan. At later stages, vocabulary facilitates integration of the word form into the lexical network.