The present study examined the composition of the early productive vocabulary of eight Korean- and eight English-learning children and the morpho-syntactic, semantic, and pragmatic characteristics of their caregivers' input in order to determine parallels between caregiver input and early lexical development. Vocabulary acquisition was followed using maternal diary and checklists for the Korean-learning children (from a mean age of 1;6 to 1;9) and for the English-learning children (from a mean age of 1;4 to 1;8). Results showed that both Korean- learning and English-learning children acquired significantly more nouns than verbs at the 50-word mark. However, Korean children learned significantly more verbs than did English-learning children. The relative ease with which Korean learners, as compared to English learners, acquired verbs parallels several differences in the linguistic and socio-pragmatic characteristics of the input addressed to them. Korean- speaking caregivers presented more activity-oriented utterances, more verbs, and more salient cues to verbs than did English-speaking caregivers. These data suggest that both general and language-specific factors shape the early lexicon.

The appearance of ‘filler syllables’ (called here PAEs, for Prefixed Additional Elements) in the late single-word period is analysed in relation to the emergence of grammatical morphemes, by confronting data from the longitudinal study of one child acquiring French, video- recorded between 1;3.2 and 2;2.6, with four hypotheses making different claims about the kind of language knowledge underlying their production: the DEVICES TO LENGTHEN SINGLE-WORD UTTERANCES, the SYNTACTIC SLOTS, the SELECTIVITY OF OCCURRENCE, and the ORGANIZATION OF SURFACE REGULARITIES hypotheses. The pattern of results concerning the first two to three months' production of PAEs points to the existence of a premorphological period in which PAEs result from the organization of phonoprosodic regularities of the language rather than being constrained by structural rules relative to syntactic slots or to the class of the word they precede. This premorphological period is followed by a protomorphological one in which incipient properties of grammatical morphemes and of word classes start to appear at the same time.

I would like to thank Katherine Demuth for all the hard work she has put in as an Associate Editor of the Journal over the last four years, and to welcome Daniel Dinnsen of Indiana University and Rosemarie Tracy of the University of Mannheim as new Associate Editors.

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This study assessed the long-term predictive validity of the MacArthur Communicative Development Inventories: Words and Sentences (CDI[ratio ]WS; Fenson, Dale, Reznick, Thal, Bates, Hartung, Pethick & Reilly, 1993) for children's expressive and receptive vocabulary development. Sixty-one New Zealand children (31 females) were assessed with a New Zealand version of the CDI[ratio ]WS at 1;7 and 2;1 and with the Expressive Vocabulary Test (Williams, 1997) and the Peabody Picture Vocabulary Test-III (Dunn & Dunn, 1997) at 2;8 and 3;4. Excellent reliability and good predictive validity was obtained for the NZ CDI[ratio ]WS even over a 21-month delay. Predictive validity of the NZ CDI[ratio ]WS for the PPVT-III was higher for children of mothers with less education. We discuss the implications of these results for use of the CDI[ratio ]WS with children from a broad range of cultural and educational backgrounds.

The phonological acquisition of 129 monolingual Putonghua-speaking children, aged 1; 6 to 4; 6, is described. Putonghua (Modern Standard Chinese) syllables have four possible elements: tone, syllable-initial consonant, vowel, and syllable-final consonant. The children's errors suggested that Putonghua-speaking children mastered these elements in the following order: tones were acquired first; then syllable-final consonants and vowels; and syllable-initial consonants were acquired last. Phonetic acquisition of the 21 syllable-initial consonants was complete by 3; 6 for 75% of children. By 4; 6 the children were using the syllable-initial consonants correctly on two thirds of occasions (with the exception of four affricates). Simple vowels emerged early in development. However, triphthongs and diphthongs were prone to systematic errors. Tone errors were rare, perhaps because of their role in distinguishing lexical meaning. In contrast, acquisition of ‘weak stress’ and ‘rhotacized feature’ was incomplete in the oldest children assessed. Phonological processes used by the children were identified. Two of these processes, syllable-initial consonant deletion and backing, would be considered atypical error patterns in English. Existing theories of phonological acquisition (e.g. concepts of markedness, functional load, feature hierarchies) cannot account for some of the patterns revealed. A satisfactory explanation of the findings requires more attention to the specific characteristics of the linguistic system the children are learning. It is proposed that the saliency of the components in the language system determines the order of acquisition.

This study examines pragmatic factors that bias English-speaking children to produce more of the nouns and fewer of the verbs that they know. If nouns are favoured for production, parents should elicit more nouns than verbs in child speech. If verb comprehension is favoured over verb production, parents should more often prompt children to produce an action than to produce a verb. Data from 44 parent–child (age 1;8) dyads in the New England directory of the CHILDES data base were analysed. Children produced more nouns than verbs but mothers produced more verbs than nouns. Speech act analyses indicate that mothers elicited noun production but rarely prompted children to produce verbs. Mothers more often prompted children to produce an action than to produce a verb, and verbs occurred most often in maternal speech acts used to elicit children's actions. Moreover, children comprehended many more verbs than they produced. These data suggest that production measures underestimate the frequency and significance of verb-learning in early lexical development.

Cultural, linguistic, and developmental evidence was taken into consideration in constructing the HCDI, a Hebrew adaptation of the MCDI. The HCDI was then administered to a stratified sample of Israeli mothers of 253 toddlers aged 1; 6 to 2; 0 (M = 1; 8·18). Hebrew results are presented and compared with scores from the original MCDI sample (Fenson, Dale, Reznick, Bates, Thal & Pethick, 1994). The HCDI is a reliable and sensitive measure of lexical development and emergent grammar, capturing wide variability among Israeli toddlers. In comparison with English, the relation between vocabulary size and age, as well as the shape of the growth curves for nouns, predicate terms, and closed class words relative to size of lexicon, were strikingly similar. These results indicate that conclusions concerning cross-linguistic similarities can be best documented by using parallel methods of measurement. The HCDI results support the claim that early lexical development in Hebrew and in English follow remarkably similar development patterns, despite the typological differences between the two target languages.

Early morphosyntax is very rich and uniform in young French-speaking children. The present study aims to give a thorough analysis of the morphosyntax produced at the outset of multi-word speech, with a classification of free language produced at 2;0 by 27 French-speaking children. The corpus was fully tagged by an automatic part-of-speech tagger. A classification performed with words taken in isolation shows a clear difference between the categories used in single-word utterances and those used in multi-word utterances. A classification performed with word sequences reveals surprisingly adult-like sequences of syntactic categories and words; the non-adult combinations are few in a French child's language. The very successful use of the tagger demonstrates the morphosyntactic coherence of the child's speech. When compared with adult language, the quantitative results, and more precisely the data concerning regularity and error types, contribute to the documentation of all the specificities of the emerging morphosyntax in normally developing French children.

Early acquisition of nouns and verbs across languages is a key issue for a number of recent studies that question the reality of the ‘noun-bias’ and wonder about the reasons why it exists as they explore the role of cognitive vs. more language-specific input factors. Addressing this issue, the present study investigates how the noun and verb word classes develop in the free speech of a French child between the ages of 1;2 and 2;6, from the perspective of semantic and grammatical development. The analyses indicate that, in French acquisition, nouns clearly predominate over verbs until age 1;8 at least, but that verbs are produced in the early stages. Concrete object names among nouns and concrete action verbs among verbs were found to be the most prevalent categories, but they were not the earliest to appear and their distribution revealed an asymmetry in the conceptual packaging of nouns and verbs. Verb grammaticalization, assessed through inflection and auxiliary use, lagged somewhat behind noun grammaticalization, assessed through determiner use. This result supports the hypothesized noun–verb grammatical asynchrony. Verb grammaticalization seems to be related to the production of concrete action verbs, and noun grammaticalization to that of concrete object nouns, indicating interactions between semantic and grammatical development. These findings, discussed in a cross-linguistic perspective, suggest that both conceptual and grammatical packaging are important and interacting factors in noun and verb development, and argue in favour of a constructivist approach to language acquisition.

Previous research has focused on evaluating the nouns and verbs in parents' input through type/token ratios. This research offers an additional means of evaluating parent speech by first examining the frequencies of individual nouns, verbs and descriptors and second examining the learning task presented to children. Study 1 examines 25 transcripts from the CHILDES database of English-speaking parents' speech to children at five developmental levels ranging from 0;11 to 2;11 in age. Study 2 examines 50 transcripts from the CHILDES database of Mandarin-speaking caregivers' speech to children ranging from 1;9 to 2;3 in age. The results suggest that the patterns of frequency for individual nouns and individual verbs are different, but that the frequency patterns for nouns and the frequency patterns for verbs are similar in English and Mandarin. Further, this research suggests that in both languages the nouns in parents' input are similarly organized: the most frequent nouns spoken to children tend to name solid objects that share a similar shape. In contrast verbs' meanings in both languages tend to include more variable conceptual relations.

Vocabulary growth from 2;0 to 3;0 was studied in 28 late talkers using expressive vocabulary inventories reported bimonthly on the Language Development Survey (LDS). Group milestones were 18 words at 2;0, 89 words at 2;6, and 195 words at 3;0. A sub-group of 11 children (Group 1) showed a rapid vocabulary spurt between 2;2 and 2;8, reached the 150–180 word mark by 2;6, and attained the LDS ceiling of about 300 words by 2;10. In contrast, the 17 children in Group 2 still had a mean vocabulary of fewer than 30 words at 2;6, had less of a vocabulary spurt when they did start acquiring words, and attained the 150–180 vocabulary mark at 3;0. All 3;0 language outcome measures were significantly predicted by LDS vocabulary size from 2;2 to 2;4.

This study investigates structural and pragmatic aspects of caregiver input in English and Korean that relate to the early development of nouns and verbs. Twenty mothers in each language were asked to interact with their one-and-a-half-year-old children in two contexts: book-reading and toy-play. Overall, English-speaking mothers use more nouns than verbs, and focus more on objects than on actions. In contrast, Korean-speaking mothers provide a balanced treatment of nouns and verbs, and focus on objects and actions to a similar degree. A significant context effect indicates that whereas English-speaking mothers emphasize nouns in both contexts, Korean-speaking mothers do so only in the Books context. In the Toys context, they provide more verbs and focus more on actions. These data suggest that systematic comparisons of caregiver input within and across different contexts provide a richer and more accurate account of the variability that can occur across languages and cultures.

The aim of the present study is to investigate the relationship between language comprehension and language production in Swedish children. This was done longitudinally with 10 children with specific language impairment (SLI), aged 4;0 to 6;3 at Time I, and 10 children with unimpaired language development, aged 3;1 to 3;7 at Time I. The target structure was subordination, more precisely relative clauses. The children's comprehension was tested with picture pointing, act-out and oral response tests. Their production was tested with elicited imitation and sentence completion tests. Data were collected twice, with an interval of six months. The results from the unimpaired children at Time I showed a difference between comprehension and production. At Time II these children scored higher on production than on comprehension. The children with SLI scored significantly higher on comprehension than on production at Time I. In half of the SLI group there was a clear development between the two data collection sessions, diminishing the dissociation. On neither testing did the children with SLI differ significantly from the unimpaired children in comprehension. At both testings, however, the children with SLI had significantly more responses where they did not insert the complementizer in relative clauses. The results indicate that the relationship between comprehension and production is different at different stages in development. They also show that structures involving dependency relations are particularly difficult to produce for children with SLI.

This paper reports the findings of a cross-sectional study that investigated the acquisition of relative clauses by 27 Tamil-speaking children, who ranged in age from 2;11 to 6;6. A picture-cued production task was used to elicit relative clauses from the child subjects. An analysis of the subjects' responses revealed that children below the age of 5;0 relativized significantly less often than the older children; furthermore, when they did produce relative clauses, they exhibited a strong preference for the tag relative and produced significantly fewer participial relatives than the older children. The findings also indicated that the younger children produced a significantly greater number of pragmatically inappropriate responses than the older children. It is argued that the observed age-related differences in Tamil children's relativizations very likely stem from performance factors and that the younger children are probably not inferior to the older children with respect to their grammatical and pragmatic competence.

This paper presents an experiment that examined two related questions. First, it examined the effects of animacy on the production of different syntactic structures and word orders by Catalan-speaking children. Secondly, it explored the relationship between age and the production of different syntactic structures by these children. The results of a picture description experiment run with eighty Catalan-speaking children aged 4; 11 to 11; 11 show that participants tended to produce more object- dislocated descriptions when the patient was animate than when the patient was inanimate. The results also show that while the dislocation of object clauses is a construction already consolidated at 5; 0, the passive structure is a construction still not fully acquired at 11; 0. A comparison between the results obtained in the present experiment with existing results from similar experiments with English-speaking children shows that there is a cross-language difference in the age at which children start producing passive clauses. We argue that frequency of exposure to a particular syntactic structure is an important factor that contributes to the acquisition of that syntactic structure. We also suggest that the effects of animacy on the production of object-dislocated descriptions can be explained by means of conceptual and lexical accessibility.

The relation of lexical and grammatical knowledge is at the core of many controversies in linguistics and psycholinguistics. Recent empirical findings that the two are highly correlated in early language development have further energized the theoretical debate. Behavioural genetics provides an illuminating new tool to explore this question, by addressing the question of whether the empirical correlation simply reflects the fact that environments which facilitate one aspect of language growth also facilitate the other, or whether the same underlying acquisition mechanisms, influenced by the same genes, are responsible for the correlation. We explored this issue in a study of 2898 pairs of two-year-old twins born in England and Wales. Language development was assessed by their parents using an adapted version of the MacArthur Communicative Development Inventory which assesses vocabulary and grammar. Moderate heritabilities were found for both. As in previous studies, measures of vocabulary and sentence complexity were substantially correlated (r = 0·66). Behaviour-genetic modelling of the relation of vocabulary and grammar produced an estimated value of 0·61 for the genetic correlation, a measure of the overlap of the genetic effects that contribute to the two aspects of language development. In contrast, a measure of nonverbal cognitive development, the PARCA, was only weakly correlated at both the phenotypic level and at the level of genetic correlations with the language measures. Thus, although the distinction between verbal and nonverbal skills has a genetic basis underlying the phenotypic dissociation, there is little evidence either genetically or phenotypically for a dissociation between vocabulary and grammar within language.

The development of specified tense and number morphology in child Catalan and Spanish is found to correlate with the onset of overt subject use. The data come from four monolingual child Catalan-speakers (from the Serrà & Solé corpus) and one monolingual child Spanish-speaker (from the Linaza corpus) who were studied longitudinally from 1:0 to 3; 6, approximately. The simultaneous emergence of tense and number morphology on one hand and overt subjects on the other in the children's speech is taken as evidence that a particular aspect of Universal Grammar, Case Theory, determines the possible co-occurrences of verbal inflections and subject types in developing grammatical systems. Parallels in verbal inflectional development are found in other child languages, while such parallels are not found in regard to subject use. Possible modifications to Case Theory, which would allow a unified account of the cross-linguistic developmental patterns of subject use, are considered. The possibility of explaining the early absence of overt subjects in these null subject languages as the result of an early sentence processing deficit is explored and rejected. The children's knowledge of whether their language is a null subject or overt subject language even before acquiring adult-like verbal inflection is taken as further evidence for what has been called ‘early convergence’ on parameter settings.

Two experiments examined phonological priming in children and adults, using a cross-modal picture-word interference task. Pictures of familiar objects were presented on a computer screen, while interfering words (IWs) were presented over headphones. In terms of their relation to target pictures, IWs were either phonologically related, unrelated, neutral (the word go), or identical. Ninety children (30 aged 4;11 to 5;11, 30 aged 6;11 to 7;11, and 30 aged 9;5 to 11;9) and 30 adults were instructed to name the pictures as quickly as possible while ignoring the IWs. In Experiment 1, related IWs shared onset consonants with the names of the pictures. Across ages, participants named pictures faster with related IWs than with unrelated IWs. In Experiment 2, related IWs rhymed with the targets. Here, only the youngest children (five to seven-year-olds) named pictures faster with related IWs than with unrelated IWs. The results indicate that priming effects reach a peak during a time when articulatory information is being consolidated in the output phonological buffer. The disappearance of the rhyme priming effect with age may reflect the gradual emergence of the onset as an organizing structure in speech production. This increased prominence of the onset can be viewed as one component of a just-in-time, incrementalist approach to speech production that allows adults to speak more fluently than children.

The aim of this study was to explain why children have difficulty with homonymy. Two experiments were conducted with forty-eight children (Experiment 1) and twenty-four children (Experiment 2). Three- and four-year-old children had to either select or judge another person's selection of a different object with the same name, avoiding identical objects and misnomers. Older children were successful, but despite possessing the necessary vocabulary, younger children failed these tasks. Understanding of homonymy was strongly and significantly associated to understanding of synonymy, and more importantly, understanding of false belief, even when verbal mental age, chronological age, and control measures were partialled out. This indicates that children's ability to understand homonymy results from their ability to make a distinction characteristic of representation, a distinction fundamental to both metalinguistic awareness and theory of mind.

Expressive language outcomes measured by MLU and the Index of Productive Syntax (IPSyn) at ages 3;0 and 4;0 were investigated in 34 late talkers with normal receptive language identified between 2;0 to 2;7 and 16 typically developing comparison children matched on age, SES, and nonverbal ability. Late talkers made greater gains than comparison children between 3;0 and 4;0 in both MLU and IPSyn raw score. However, when age-standardized z-scores were analysed, the late talkers were about 2·5 standard deviations below comparison children on both measures at both ages. At 3;0, 41% of the late talkers had MLUs above the 10th percentile based on Scarborough's (1990) benchmark sample; by 4;0, 71% did so. Using the IPSyn, a more stringent measure, 34% scored above the 10th percentile at 3;0 and only 29% did so at 4;0. MLU was significantly correlated with the IPSyn at both ages for the late talkers, but only at 3;0 for the comparison children. A converging set of regression analyses indicated no group differences in the predictive relationship between MLU and IPSyn, suggesting that the late talkers were delayed on both measures but not deviant in their development.