The purpose of this research was to show how the syntactic and semantic components of the tense–aspect system interact during the acquisition process. Our methodology involved: (1) identifying predicates, (2) finding the initial occurrence of their tense–aspect morphology, and (3) observing the emergence of contrasts. Six children learning Polish and six children learning English, found in the CHILDES archives, were investigated. The average starting age of the children learning English was 1;11, and 1;8 for the children learning Polish. In the first analysis, we traced the same 12 verbs in both languages, and in the second analysis, we contrasted the acquisition patterns for a set of telic versus atelic predicates. We tracked the verbs/predicates from the starting age to 4;11 or the child's final transcript. In English, progressive aspect is the marked form, and in Polish, perfective aspect is the marked form. This typological distinction has a significant effect of the acquisition patterns in the two languages. We argue that children acquire a multi-dimensional system having deictic relations as one of the basic dimensions. This process can be best understood within a functional theoretical framework having a well-defined syntactic–semantic interface.

This paper examines the production of word-initial stops by two simultaneous trilingual sisters, aged 6;8 and 8;1, who receive regular input in Italian and English from multiple speakers, but in Spanish from only one person. The children's productions in each language were analyzed acoustically and compared to those of their main input providers. The results revealed consistent cross-linguistic differences by both children, including between Italian and Spanish stops, although these have identical properties in the speech of Italian- and Spanish-speaking adults. While the children's English stops were largely target-like, their Italian stops exhibited non-target-like realizations in the direction of English, suggesting interactions. Interestingly, their Spanish productions were largely unaffected by cross-linguistic interactions, with target-like voiceless stops, and voiced stops predominantly realized as spirants. These findings raise interesting questions about phonological development in multilingual settings and demonstrate that the number and type of input providers may crucially affect cross-linguistic interactions.

In many contexts, pronouns are interpreted as referring to the character mentioned first in the previous sentence, an effect called the ‘first-mention bias’. While adults can rapidly use the first-mention bias to guide pronoun interpretation, it is unclear when this bias emerges during development. Curiously, experiments with children between two and three years old show successful use of order of mention, while experiments with older children (four to five years old) do not. While this could suggest U-shaped development, it could also reflect differences in the methodologies employed. We show that children can indeed use first-mention information, but do so too slowly to have been detected in previous work reporting null results. Comparison across the present and previously published studies suggests that the speed at which children deploy first-mention information increases greatly during the preschool years.

Several theoretical and descriptive challenges are presented by children's phonological substitution errors which interact to yield the effect of a chain shift. Drawing on an archival study of the sound systems of five children (ages 3;5 to 4;0) with normal development and 47 children (ages 3;4 to 6;8) with phonological delay, one such chain shift, namely the replacement of target /Θ/ by [f] and the replacement of /s/ by [Θ/, was identified in the speech of six children from the two subgroups. Different derivational and constraint-based accounts of the chain shift were formulated and evaluated against the facts of change and the children's presumed perceptual abilities. An adequate account in either framework was found to require the postulation of underspecified and, in some instances, nonadult-like underlying representations. Such representations were able to reconcile within a single-lexicon model the presumed production/perception dilemma commonly associated with acquisition. Continuity was also preserved by limiting underlying change to just those lexical items which exhibited a change phonetically.

Infants are adept at learning statistical regularities in artificial language materials, suggesting that the ability to learn statistical structure may support language development. Indeed, infants who perform better on statistical learning tasks tend to be more advanced in parental reports of infants’ language skills. Work with adults suggests that one way statistical learning ability affects language proficiency is by facilitating real-time language processing. Here we tested whether 15-month-olds’ ability to learn sequential statistical structure in artificial language materials is related to their ability to encode and interpret native-language speech. Specifically, we tested their ability to learn sequential structure among syllables (Experiment 1) and words (Experiment 2), as well as their ability to encode familiar English words in sentences. The results suggest that infants' ability to learn sequential structure among syllables is related to their lexical-processing efficiency, providing continuity with findings from children and adults, though effects were modest.

The Agreement/Tense Omission Model (ATOM) predicts that English-speaking children will show similar patterns of provision across different tense-marking morphemes (Rice, Wexler & Hershberger, 1998). The aim of the present study was to test this prediction by examining provision rates for third person singular present tense and first and third person singular forms of copula BE and auxiliary BE in longitudinal data from eleven English-speaking children between the ages of 1 ; 10 and 3 ; 0. The results show, first, that there were systematic differences in the provision rates of the different morphemes; second, that there were systematic differences in the rate at which all of the three morphemes were provided with pronominal and lexical subjects; and, third, that there were systematic differences in the rate at which copula BE and auxiliary BE were provided with the third person singular pronominal subjects It and He and the first person singular subject pronoun I. These results replicate those of Wilson (2003), while controlling for some possible objections to Wilson's analysis. They thus provide further evidence against the generativist view that children's rates of provision of different tense-marking morphemes are determined by a single underlying factor, and are consistent with the constructivist view that children's rates of provision reflect the gradual accumulation of knowledge about tense marking, with much of children's early knowledge being embedded in lexically specific constructions.

To explore the relationship of language use and speech adaptation to role and context the spontaneous speech of a boy aged 5; 6 was recorded in three different situations: playing alone, playing with a friend of the same age, and playing with his mother. Several analyses were made of the speech transcripts to examine the relationship between context and language use. The nature of play episodes was also investigated. The findings suggest that role play has an important function in the development of a child's ability to communicate effectively, and that a child's awareness of his own role and the expectations he has concerning social interactions lead to modification in language use.

The objective of this work was to analyze morphosyntactic development in a wide sample of children with Down syndrome (DS) (n = 92) and children with typical development (TD) (n = 92) with a mental age (MA) of 20 to 29 months. Children were individually matched for gender and MA (Analysis 1) and for vocabulary size (Analysis 2). Information about morphosyntax was obtained using an adaptation of the CDI for children with DS. In both analyses, the number of children with DS and with TD who combined words was similar. Analysis 1 showed that children with DS produced shorter utterances, with less morphosyntactic complexity and less morphological suffixes than children with TD, despite having the same mental age. The developmental pattern was similar, although slower in children with DS. Analysis 2 showed that the performance of children with DS was lower than the performance of children with TD in relation to morphosyntactic complexity and morphological suffixes.

Expressive vocabulary data gathered during a systematic diary study of one male child's early language development are compared to data that would have resulted from longitudinal administration of the MacArthur Communicative Development Inventories spoken vocabulary checklist (CDI). Comparisons are made for (1) the number of words at monthly intervals (9;10.15 to 2;0.15), (2) proportion of words by lexical class (i.e. noun, predicate, closed class, ‘other’), (3) growth curves. The CDI underestimates the number of words in the diary study, with the underestimation increasing as vocabulary size increases. The proportion of diary study words appearing on the CDI differed as a function of lexical class. Finally, despite the differences in vocabulary size, logistic curves proved to be the best fitting model to characterize vocabulary development as measured by both the diary study and the CDI. Implications for the longitudinal use of the CDI are discussed.

I first outline three major developments in child language research over the past forty years: the use of computational modelling to reveal the structure of information in the input; the focus on quantifying productivity and abstraction; and developments in the explanation of systematic errors. Next, I turn to what I consider to be major outstanding issues: how the network of constructions builds up and the relationship between social and cognitive development and language learning. Finally, I briefly consider a number of other areas of importance to a psychologically realistic understanding of children's language development.

This is a naturalistic study of the development of language in Hebrew-speaking children with Williams syndrome (WS) and children with Down syndrome (DS), whose MLU extended from 1·0 to 4·4. Developmental curves over the entire span of data collection revealed minor differences between children with WS, children with DS, and typically developing (TD) controls of similar MLU. Development within one calendar year showed remarkable synchrony among the variables. However, age of language onset and pace of acquisition departed significantly from normal timing. It is argued that in view of the centrality of genetic timing and the network properties of cognition, normal schedules are crucial determinants of intact development. Consequently, with respect to neurodevelopmental syndromes, the so-called ‘language delay’ is indicative of deviance that is likely to impact development in critical ways.

Previous research has rarely compared the contributions of different underlying abilities to phonological acquisition. In this study, the auditory-visual speech perception, oro-motor and rule abstraction skills of 62 typically developing two-year olds were assessed and contrasted with the accuracy of their spoken phonology. Measures included auditory-visual speech perception, production of isolated and sequenced oro-motor movements, and verbal and non-verbal rule abstraction. Abilities in all three domains contributed to phonological acquisition. However, the use of atypical phonological rules was associated with lower levels of phonological accuracy and a linear regression indicated that this measure of rule abstraction had greater explanatory power than the measures of input processing and output skill.

This study investigates the contributions of semantic, phonological, and orthographic factors to morphological awareness of 413 Chinese-speaking students in Grades 2, 4, and 6, and its relationship with reading comprehension. Participants were orally presented with pairs of bimorphemic compounds and asked to judge whether the first morphemes of the words shared a meaning. Morpheme identity (same or different), whole-word semantic relatedness (high or low), orthography (same or different), and phonology (same or different) were manipulated. By Grade 6, children were able to focus on meaning similarities across morphemes while ignoring the distraction of form, but they remained influenced by whole-word semantic relatedness. Children's ability to overcome the distraction of phonology consistently improved with age, but did not reach ceiling, whereas the parallel ability for orthography reached ceiling at Grade 6. Morphological judgment performance was a significant unique predictor of reading comprehension when character naming and vocabulary knowledge were accounted for.

Previous studies suggest that age of acquisition affects the outcomes of learning, especially at the morphosyntactic level. Unknown is how syntactic development is affected by increased cognitive maturity and delayed language onset. The current paper studied the early syntactic development of adolescent first language learners by examining word order patterns in American Sign Language (ASL). ASL uses a basic Subject–Verb–Object order, but also employs multiple word order variations. Child learners produce variable word order at the initial stage of acquisition, but later primarily produce canonical word order. We asked whether adolescent first language learners acquire ASL word order in a fashion parallel to child learners. We analyzed word order preference in spontaneous language samples from four adolescent L1 learners collected longitudinally from 12 months to six years of ASL exposure. Our results suggest that adolescent L1 learners go through stages similar to child native learners, although this process also appears to be prolonged.

This study examines pragmatic differentiation in early trilingual development through a longitudinal analysis of language choice in a developing Tagalog–Spanish–English trilingual child. The child's patterns of language choice with different language users are analyzed at age 1 ; 10 and 2 ; 4 to examine: (1) whether evidence for pragmatic differentiation can be found even before age two and in simultaneous interactions with distinct language users; (2) whether lexical gaps determine the child's choice of one language over another; and (3) whether her patterns of language choice are affected by the interlocutors language use and their responses to mixing. The results indicate that the child was capable of selecting the appropriate language according to the interlocutors' language from the earliest sessions. However, switches to inappropriate languages were common due to vocabulary gaps, the interlocutors' acceptance of mixing and the possibilities determined by the existence of multiple lexical resources and multiple language users.

How do children develop the mapping between prosody and other levels of linguistic knowledge? This question has received considerable attention in child language research. In the present study two experiments were conducted to investigate four- to five-year-old Mandarin-speaking children's sensitivity to prosody in ambiguity resolution. Experiment 1 used eye-tracking to assess children's use of stress in resolving structural ambiguities. Experiment 2 took advantage of special properties of Mandarin to investigate whether children can use intonational cues to resolve ambiguities involving speech acts. The results of our experiments show that children's use of prosodic information in ambiguity resolution varies depending on the type of ambiguity involved. Children can use prosodic information more effectively to resolve speech act ambiguities than to resolve structural ambiguities. This finding suggests that the mapping between prosody and semantics/pragmatics in young children is better established than the mapping between prosody and syntax.

Voice onset time (VOT) characteristics of stops in initial clusters in American English words produced by children and adults were studied. Words were spoken in isolation and in sentence context by eleven three-and four-year-old children, and by a male and female adult. Spectrograms were made and VOT duration measurements taken. Three experienced listeners transcribed the isolated words and sentences. Analyses showed that overall timing characteristics were similar for children and adults. Speakers differed in their [±voice] boundary and there was no absolute time distinction between [±voice] stops; [+voice] stops showed less variability than [−voice]. VOT generally increased from labial to dental to velar clusters, and was shorter in sentence context and longer in clusters than in singletons. Children's VOT averages were generally, but not significantly, longer than adults' in all contexts, and coarticulation constraints affected the accuracy with which children produced the stop and liquid portion of a particular cluster.

Evidentials are grammatical source-of-knowledge markers. In Bulgarian they provide information about authorship – whether the speaker has personally acquired the information or not – and modality – whether perceptual or cognitive mechanisms were involved in the information's generation. In two experiments, Bulgarian kindergarteners and third-graders (ages 6 and 9, N=96) had to decide which one of two utterances containing different evidentials to believe. Experiment 1 showed that children draw on modality information in their decisions: Third-graders favored perceptual over cognitive and kindergartners cognitive over perceptual sources. Experiment 2 showed that third-graders can also draw on the authorship information carried by evidentials: they favored first- over second-hand information. The discussion focuses on understanding the development of children's use of evidentials.

As Ravid & Tolchinsky (2002) have indicated in their article, literacy has profound effects upon the development of language in school-age children, adolescents, and adults. Once children are able to read proficiently – typically by eight or nine years – their ability to acquire increasingly sophisticated aspects of language can expand greatly. The convergence of language and literacy is readily apparent upon examining the lexicon, a language domain that is subject to unlimited growth through the lifespan. For this reason, I would like to elaborate on the role of literacy in relation to lexical development beyond the preschool years, focusing on processes that facilitate the learning of word meanings. In this commentary, it will be shown that there is an ongoing reciprocal relationship between lexical development and literacy in which unfamiliar words are first encountered in print and learned through various metalinguistic strategies. Subsequently, this increased knowledge of words leads to improved comprehension of text, which in turn, leads to further expansion of the lexicon (Sternberg & Powell, 1983).