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.

The acoustic-phonetic realizations of words can vary dramatically depending on a variety of within- and across-talker characteristics such as regional dialect, native language, age, and gender. Robust word learning requires that children are able to recognize words amidst this substantial variability. In the current study, perception of foreign-accented words was assessed in four- to seven-year-old children to test how one form of variability influences word recognition in children. Results demonstrated that children had less accurate word recognition than adults for both native- and foreign-accented words. Both adults and children were less accurate at identifying foreign-accented words compared to native-accented words with children and adults showing similar decrements. For children, age and lexicon size contributed to accurate word recognition.

Children's ability to learn and retain new words is fundamental to their vocabulary development. This study examined word retention in children learning a home language (L1) from birth and a second language (L2) in preschool settings. Participants were presented with sixteen novel words in L1 and in L2 and were tested for retention after either a 2-month or a 4-month delay. Results showed that children retained more words in L1 than in L2 for both of the retention interval conditions. In addition, children's word retention was associated with their existing language knowledge and their fast-mapping performance within and across language. The patterns of association, however, were different between L1 and L2. These findings suggest that children's word retention might be related to the interactions of various components that are operating within a dynamic system.

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.

The aim of the present study was to examine the contextual effects of social games on prelinguistic vocalizations. The two main goals were to (1) investigate the functions of vocalizations as symptoms of affective arousal and symbols of social understanding, and (2) explore form–function (de)coupling relations between vocalization types and game contexts. Seventy-one six-month-olds and sixty-four twelve-month-olds played with their mothers in normal and perturbed tickle and peek-a-boo games. The effects of infant age, game, game climax, and game perturbation on the frequency and types of infant vocalizations were examined. Results showed twelve-month-olds vocalized more mature canonical syllables during peek-a-boo and more primitive quasi-resonant nuclei during tickle than six-month-olds. Six- and twelve-month-olds increased their vocalizations from the set-up to climax during peek-a-boo, but they did not show such an increase during tickle. Findings support the symptom function of prelinguistic vocalizations reflecting affective arousal and the prevalence of form–function decoupling during the first year of life.

Understanding how linguistic cues map to the environment is crucial for early language comprehension and may provide a way for bootstrapping and learning words. Research has suggested that learning how plural syntax maps to the perceptual environment may show a trajectory in which children first learn surrounding cues (verbs, modifiers) before a full mastery of the noun morpheme alone. The Spanish plural system of simple codas, dominated by one allomorph -s, and with redundant agreement markers, may facilitate early understanding of how plural linguistic cues map to novel referents. Two-year-old Mexican children correctly identified multiple novel object referents when multiple verbal cues in a phrase indicated plurality as well as in instances when the noun morphology in novel nouns was the only indicator of plurality. These results demonstrate Spanish-speaking children's ability to use plural noun inflectional morphology to infer novel word referents which may have implications for their word learning.

This study investigated the integration of word- and phrase-level prominences in speech produced by twenty-five school-aged children (6;2 to 7;3) and twenty-five adults. Participants produced disyllabic number words in a straight count condition and in two phrasal conditions, namely, a stress clash and non-clash phrasal context. Duration and amplitude measures of syllable rhymes were used to assess the realization of lexical stress, and fundamental frequency (F0) measures were used to assess the realization of phrasal pitch accents across conditions. Results showed that the duration and F0 correlates varied independently of each other as a function of condition in child speech, but much less so in adult speech. The group differences were taken to indicate that six-year-old children have yet to develop prosodic structures with integrated prominence. Structural and pragmatic interpretations of the results are discussed.

Language processing plays a crucial role in language development, providing the ability to assign structural representations to input strings (e.g., Fodor, 1998). In this paper we aim at contributing to the study of children's processing routines, examining the operations underlying the auditory processing of relative clauses in children compared to adults. English-speaking children (6;0–8;11) and adults participated in the study, which employed a self-paced listening task with a final comprehension question. The aim was to determine (i) the role of number agreement in object relative clauses in which the subject and object NPs differ in terms of number properties, and (ii) the role of verb morphology (active vs. passive) in subject relative clauses. Even though children's off-line accuracy was not always comparable to that of adults, analyses of reaction times results support the view that children have the same structural processing reflexes observed in adults.

It is widely agreed that learning to read starts with the establishment of letter-to-phoneme correspondences. However, it is also widely agreed that prereaders do not have access to phoneme units. Here we show that the building of associations between letters and syllables, which we call the ‘syllabic bridge’, might be a faster and more direct way of learning spelling-to-sound correspondences in French. After a few minutes of exposure, prereaders are able to learn the statistical properties of letter co-occurrences. Statistical learning is boosted by explicit instructions about the associations between letter clusters and syllables. Building the syllabic bridge from available phonological syllables and frequent letter clusters may therefore be the first step in learning to read.

Typically, the point vowels [i,ɑ,u] are acoustically more peripheral in infant-directed speech (IDS) compared to adult-directed speech (ADS). If caregivers seek to highlight lexically relevant contrasts in IDS, then two sounds that are contrastive should become more distinct, whereas two sounds that are surface realizations of the same underlying sound category should not. To test this prediction, vowels that are phonemically contrastive ([i–ɪ] and [eɪ–ε]), vowels that map onto the same underlying category ([æ–] and [ε–]), and the point vowels [i,ɑ,u] were elicited in IDS and ADS by American English mothers of two age groups of infants (four- and eleven-month-olds). As in other work, point vowels were produced in more peripheral positions in IDS compared to ADS. However, there was little evidence of hyperarticulation per se (e.g. [i–ɪ] was hypoarticulated). We suggest that across-the-board lexically based hyperarticulation is not a necessary feature of IDS.

Pronunciation variation is under-studied in infant-directed speech, particularly for consonants. Regressive place assimilation involves a word-final alveolar stop taking the place of articulation of a following word-initial consonant. We investigated pronunciation variation in word-final alveolar stop consonants in storybooks read by forty-eight mothers in adult-directed or infant-directed style to infants aged approximately 0;3, 0;9, 1;1, or 1;8. We focused on phonological environments where regressive place assimilation could occur, i.e., when the stop preceded a word-initial labial or velar consonant. Spectrogram, waveform, and perceptual evidence was used to classify tokens into four pronunciation categories: canonical, assimilated, glottalized, or deleted. Results showed a reliable tendency for canonical variants to occur in infant-directed speech more often than in adult-directed speech. However, the otherwise very similar distributions of variants across addressee and age group suggested that infants largely experience statistical distributions of non-canonical consonantal pronunciation variants that mirror those experienced by adults.

Eight children aged 4;1–8;1 and their primary caregivers participated in a study designed to evaluate their use of the onset cluster /str-/ in both read and conversational speech. The cluster is currently undergoing a reported sound change in many varieties of English, with the initial /s/ being retracted to [ʃ]. The study compared the initial fricative of the cluster in both the children and their mothers. Acoustic analysis was carried out in order to categorize tokens as either [s] or [ʃ] using spectral peak analysis. Results found that children as young as 5;1 were starting to exhibit the usage patterns of their mothers. The distribution of the novel variant suggests that the children may be learning this form via a process of lexical diffusion rather than by rule. Implications for the study of dialect acquisition and phonological acquisition in general are discussed.

In this paper, we ask whether children are sensitive to the needs of their interlocutor, and, if so, whether they – like adults – modify acoustic characteristics of their speech as part of a communicative goal. In a production task, preschoolers participated in a word learning task that favored the use of clear speech. Children produced vowels that were longer, more intense, more dispersed in the vowel space, and had a more expanded F0 range than normal speech. Two perception studies with adults showed that these acoustic differences were perceptible and were used to distinguish normal and clear speech styles. We conclude that preschoolers are sensitive to aspects of the speaker–hearer relationship calling upon them to modify their speech in ways that benefit their listener.

Previous studies on the role of vowel harmony in word segmentation are based on artificial languages where harmonic cues reliably signal word boundaries. In this corpus study run on the data available at CHILDES, we investigated whether natural languages provide a learner with reliable segmentation cues similar to the ones created artificially. We observed that in harmonic languages (child-directed speech to thirty-five Turkish and three Hungarian children), but not in non-harmonic ones (child-directed speech to one Farsi and four Polish children), harmonic vowel sequences are more likely to appear within words, and non-harmonic ones mostly appear across word boundaries, suggesting that natural harmonic languages provide a learner with regular cues that could potentially be used for word segmentation along with other cues.

Young children are skilled language learners. They apply their skills to the language input they receive from their parents and, in this way, derive patterns that are statistically related to their input. But being an excellent statistical learner does not explain why children who are not exposed to usable linguistic input nevertheless communicate using systems containing the fundamental properties of language. Nor does it explain why learners sometimes alter the linguistic input to which they are exposed (input from either a natural or an artificial language). These observations suggest that children are prepared to learn language. Our task now, as it was in 1974, is to figure out what they are prepared with – to identify properties of language that are relatively easy to learn, the resilient properties, as well as properties of language that are more difficult to learn, the fragile properties. The new tools and paradigms for describing and explaining language learning that have been introduced into the field since 1974 offer great promise for accomplishing this task.

Previous research shows that two-year-olds' third person singular -s and plural -s are produced more accurately in utterance-final compared to utterance-medial position. However, only the third person singular is affected by coda complexity. This study explores these effects with possessive -s. Acoustic analysis of twelve two-year-olds' elicited imitations examined the use of simple versus complex codas (e.g. Sue's vs. Doug's) both utterance-medially and utterance-finally. Morpheme production was surprisingly robust across contexts, though coda clusters were often simplified to a lengthened -s morpheme utterance-medially (e.g., Dou's [dɐz]). The findings raise many questions about the development of speech planning processes across populations.

In many of the world's languages grammatical aspect is used to indicate how events unfold over time. In English, activities that are ongoing can be distinguished from those that are completed using the morphological marker -ing. Using naturalistic observations of two children in their third year of life, we quantify the availability and reliability of the imperfective form in the communicative context of the child performing actions. On average, 30% of verbal descriptions refer to child actions that are grounded in the here-and-now. Of these utterances, there are two features of the communicative context that reliably map onto the functions of the imperfective, namely, that events are construed as ongoing and from within. The findings are discussed with reference to how the context in which a child hears aspectual language may limit the degrees of freedom on what these constructions mean.

Several models of language acquisition have emerged in recent years that rely on computational algorithms for simulation and evaluation. Computational models are formal and precise, and can thus provide mathematically well-motivated insights into the process of language acquisition. Such models are amenable to robust computational evaluation, using technology that was developed for Information Retrieval and Computational Linguistics. In this article we advocate the use of such technology for the evaluation of formal models of language acquisition. We focus on the Traceback Method, proposed in several recent studies as a model of early language acquisition, explaining some of the phenomena associated with children's ability to generalize previously heard utterances and generate novel ones. We present a rigorous computational evaluation that reveals some flaws in the method, and suggest directions for improving it.