A common assumption underlying the semantic feature and the functional core hypotheses of lexical development is that attributes abstracted from the referents of a word are sufficient to determine the extension of that word. The present paper begins by challenging this assumption. A contrastive hypothesis is instead advanced to explain the early lexical development of children, and the predictions of this hypothesis are shown to be consistent with available data on overextension. The paper concludes with a critical discussion of the semantic feature and the functional core hypotheses in which it is shown that neither of these hypotheses can account for the data on overextension.

There have been many studies examining the differences between infant-directed speech (IDS) and adult-directed speech (ADS). However, investigations asking whether mothers clarify vowel articulation in IDS have reached equivocal findings. Moreover, it is unclear whether maternal speech clarification has any effect on a child's developing language skills. This study examined vowel clarification in mothers’ IDS at 0;10–11, 1;6, and 2;0, as compared to their vowel production in ADS. Relationships between vowel space, vowel duration, and vowel variability and child language outcomes at two years were also explored. Results show that vowel space and vowel duration tended to be greater in IDS than in ADS, and that one measure of vowel clarity, a mother's vowel space at 1;6, was significantly related to receptive as well as expressive child language outcomes at two years of age.

In this study vocabulary development of a sample of 42 Italian children was evaluated through monthly administration of the Italian version of the CDI. Data collection started at 1;0–1;1 for 32 children and at 1;3–1;4 for the remaining subjects and continued until children's vocabulary reached 200 words. At fixed stages of vocabulary size (50, 100 and 200 words), individual differences in percentile scores and vocabulary composition were examined. Individual growth curves were analysed in order to verify the presence of a vocabulary spurt and the type of lexical items which contributed most to rapid acceleration in vocabulary growth.

Stylistic differences in vocabulary composition were examined regarding the ‘referential–expressive’ distinction, controlling vocabulary size. Data have shown that general trends in vocabulary development are quite similar to those obtained for other languages using CDI adaptations. Moreover, all children in this sample eventually exhibited a vocabulary spurt, even if some can be defined as ‘late spurters’. The type of lexical items which are learned during the spurt depend on both infant vocabulary size and referential score. About 28% of infants in this sample were defined ‘referential’ when their vocabulary size was about 50 words, but the stylistic differences disappeared at the 100- and 200-word stages.

Composition of vocabulary did not differ in relation to precocity in reaching different stages of vocabulary development. The only exception was that infants who reached the 50-word stage first also had a vocabulary with a lower proportion of function words.

The production of target consonant clusters at early stages of acquisition is analysed from a phonological representational perspective. The data stem from five normal monolingual German and four normal monolingual Spanish children at ages from 0;9 to 2;1, observed in naturalistic settings. At the beginning stages, target clusters are reduced to a single consonantal position, due to lack of branching of the syllabic constituents. This finding coincides with other results in the literature, which have in general been explained by means of universal principles. Nevertheless, there is an essential difference between the German and the Spanish data: German children tend to prefer the first consonant and Spanish children the second one. This difference can only be explained in terms of parameterization of syllabification, which in German takes place from left to right and in Spanish from right to left. At later stages, when clusters begin to be produced with two consonantal positions, they offer evidence for the beginning of branching of syllabic constituents, due to parameterization, and for the chronological order of the setting of the subsyllabic parameters. Our data offer evidence in favour of the following acquisitional hierarchy: CV > CVC > CVCC > CCVCC.

This study compared the receptive and expressive language profiles of verbally expressive children and adolescents with Down Syndrome (DS) and those with Fragile X syndrome (FXS) and examined the extent to which these profiles reliably differentiate the diagnostic groups. A total of twenty-four verbal participants with DS (mean age: 12 years), twenty-two verbal participants with FXS (mean age: 12 years), and twenty-seven participants with typical development (TD; mean age = 4 years) completed standardized measures of receptive and expressive vocabulary and grammar, as well as a conversational language sample. Study results indicate that there are distinct DS and FXS language profiles, which are characterized by differences in grammatical ability. The diagnostic groups were not differentiated based on vocabulary performance. This study supports the existence of unique language profiles associated with DS and FXS.

Lexical gaps in vocabulary development have been acknowledged as a reason for language mixing in young bilingual children. In spite of this, most studies do not take into account whether young bilinguals have the lexical resources to make a choice between their two languages. Inferences are nevertheless still being made about whether or not young bilinguals differentiate between their two languages based on language choice. It is widely believed, however, that young bilinguals do not have the resources to make lexical choices at a pre-syntactic stage of development before age two. A bilingual case study of an infant acquiring Spanish and English from birth to age 1;10 is used to address this issue. Daily diary records and weekly video recordings in the two language contexts are used to construct the child's lexicon and to establish that translation equivalents that make possible language choice are available from the beginning of speech. The results are used to discuss the importance of translation equivalents in the bilingual lexicon for viable interpretations of language choice.

The capacity to perceive similarity between apparently dissimilar domains is widely regarded as crucial to creative thought; yet little is known about the development of this ‘metaphoric’ skill. To assess children's capacities to effect appropriate ‘metaphoric links’, and to discriminate among metaphors of varying appropriateness, a task probing verbal metaphoric skill was designed. Subjects ranging in age from 4 to 19 years were required to complete a simile and then to choose from a set of four similes the one most appropriate for a given literary context. The study documented a tendency, increasing with age, towards preference for an appropriate metaphor. Whereas primary school children preferred non-metaphoric endings and preadolescents favoured conventional metaphors, high school and college students showed significant appreciation of appropriate metaphors. In contrast, conventional metaphors predominated in the subjects' productions and appropriate metaphors were rarely produced by subjects of any age group. Unexpectedly, the highest percentages of appropriate metaphors were produced by the youngest subjects and the oldest subjects. Where these two groups differed was in the proclivity of young subjects to produce metaphors which were highly original but inappropriate or nonsensical. The various strategies used by subjects of different ages are described and the relations between metaphoric productions and preferences are considered.

When bilingual children enter formal reading education, host language proficiency becomes increasingly important. This study investigated the relation between socioeconomic status (SES), maternal language use, reading input, and vocabulary in a sample of 111 six-year-old children of first- and second-generation Turkish immigrant parents in the Netherlands. Mothers reported on their language use with the child, frequency of reading by both parents, and availability of children's books in the ethnic and the host language. Children's Dutch and Turkish vocabulary were tested during a home visit. SES was related to maternal language use and to host language reading input. Reading input mediated the relation between SES and host language vocabulary and between maternal language use and host language vocabulary, whereas only maternal language use was related to ethnic language vocabulary. During transition to formal reading education, one should be aware that children from low-SES families receive less host language reading input.

In this study it is argued that the omission of closed class morphemes and of unstressed syllables within words is related to their common characteristic, viz. that they are unstressed, rhythmically weak parts of utterances. Several strands of evidence indicate that it is unlikely that children are unable to perceive these elements in the input speech. The pattern of (non)realization of unstressed syllables within content words and the class of determiners, was analysed in two Dutch children from 1;6 to 2;11. It appeared that polysyllabic words were quite generally truncated in such a way that they fitted a trochaic (strong-weak) pattern, particularly in the early samples. Some observations with respect to the (non)realization of determiners are suggestive of an influence of an SW-constraint on the realization of noun phrases. These findings support the hypothesis that in the course of utterance preparation, words and phrases are mapped onto S(W) templates. Anecdotal evidence suggests that the dissolution of the SW-constraint coincides with the acquisition of specific aspects of stress assignment in Dutch, such as quantity sensitivity.

Bilingual children are a more heterogenous group than their monolingual counterparts with respect to the sources of variation in their language learning environments, as well as the wide individual variation in their language abilities. Such heterogeneity in both individual difference factors and language abilities argues for the importance of an individual differences approach in research on bilingual development. The main objective of this article is to provide a review and synthesis of research on the sources of individual differences in the second language (L2) and heritage language (HL) development of child bilinguals. Several child-internal and child-external individual difference factors are discussed with respect to their influence on children’s dual language abilities. In addition, the emergent research on individual differences in bilingual children with developmental language disorder is reviewed. Both the theoretical and applied relevance of individual difference approaches to bilingual development are discussed.

This paper focuses on the aspects of the lexicon in 66 prematurely born very-low-birth-weight and 87 full-term Finnish children at 2;0, studied using the Finnish version of the MacArthur Communicative Developmental Inventory. The groups did not differ in vocabulary size. Furthermore, the female advantage in vocabulary size was not seen in preterm children. The overall shapes of the trajectories for the main lexical categories as a function of vocabulary size were highly similar in both groups and followed those described in the literature. However, there were significant differences in the percentage of nouns and grammatical function words between the two groups. The results suggest that prematurity ‘cuts off’ the female advantage in vocabulary development. Furthermore, it also seems that there are differences between prematurely born and full-term children in the composition of the lexicon at 2;0. The findings support the universal sequence in the development of lexical categories.

This longitudinal study assessed three acoustic components of maternal infant-directed speech (IDS) – pitch, affect, and vowel hyperarticulation – in relation to infants’ age and their expressive vocabulary size. These three individual components were measured in IDS addressed to infants at 7, 9, 11, 15, and 19 months (N = 18). All three components were exaggerated at all ages in mothers’ IDS compared to their adult-directed speech. Importantly, the only significant predictor of infants’ expressive vocabulary size at 15 and 19 months was vowel hyperarticulation, but only at 9 months and beyond, not at 7 months, and not pitch or affect at any age. These results set apart vowel hyperarticulation in IDS to infants as the critical IDS component for vocabulary development. Thus IDS, specifically the degree of vowel hyperarticulation therein, is a vehicle by which parents can provide the most optimal speech quality for their infants’ linguistic and communicative development.

The types of gesture+speech combinations children produce during the early stages of language development change over time. This change, in turn, predicts the onset of two-word speech and thus might reflect a cognitive transition that the child is undergoing. An alternative, however, is that the change merely reflects changes in the types of gesture+speech combinations that their caregivers produce. To explore this possibility, we videotaped 40 American child–caregiver dyads in their homes for 90 minutes when the children were 1;2, 1;6, and 1;10. Each gesture was classified according to type (deictic, conventional, representational) and the relation it held to speech (reinforcing, disambiguating, supplementary). Children and their caregivers produced the same types of gestures and in approximately the same distribution. However, the children differed from their caregivers in the way they used gesture in relation to speech. Over time, children produced many more REINFORCING (bike+point at bike), DISAMBIGUATING (that one+point at bike), and SUPPLEMENTARY combinations (ride+point at bike). In contrast, the frequency and distribution of caregivers' gesture+speech combinations remained constant over time. Thus, the changing relation between gesture and speech observed in the children cannot be traced back to the gestural input the children receive. Rather, it appears to reflect changes in the children's own skills, illustrating once again gesture's ability to shed light on developing cognitive and linguistic processes.

This study aimed to investigate early lexical and grammatical development and their relations in a sample of very immature healthy preterms, in order to assess whether their linguistic development was typical, at risk or atypical. The effects of biological factors and parental level of education on preterms' linguistic development were also investigated. Seventy-three Italian preterms and 22 Italian fullterms (control sample) were assessed at 2;6 with an Italian test of repetition of sentences (TRF). Their mothers completed the Italian version of the MacArthur questionnaire (PVB). Our results showed that most of the preterm sample displayed a typical development, compared with the fullterms, with lexicon and grammar within the normal range and a normal relation between these competencies. However, preterms characterized by an extremely low birthweight (ELBW), a very low gestational age and male gender were at risk, with slight delays in the lexicon and grammar, but still retaining the normal relation between the two.

English-speaking children make pronoun case errors producing utterances where accusative pronouns are used in nominative contexts (me do it). We investigate whether complex utterances in the input (Let me do it) might explain the origin of these errors. Longitudinal naturalistic data from seventeen English-speaking two- to four-year-olds was searched for 1psg accusative-for-nominative case errors and for all 1psg preverbal pronominal contexts. Their caregivers' data was also searched for 1psg preverbal pronominal contexts. The data show that the children's proportional use of me-for-I errors correlated with their caregivers' proportional use of me in 1psg preverbal contexts. Furthermore, the verbs that children produced in me-error utterances appeared in complex sentences containing me in the input more often than verbs that did not appear in me-for-I errors in the children's speech. These findings are discussed in the context of current explanations for children's case marking errors.

Children's acquisition of noun pluralization patterns in Hebrew was studied longitudinally and cross-sectionally. The data show that, through the period of acquisition (age 2–3), children make maximal use of the available morphophonological clues for pluralization; they determine their choice of the plural morpheme according to the nature of the final syllable of the noun singular. They seem totally insensitive to the semantic notion of gender which governs the choice of plurals for animate nouns, as well as to a syntactic notion of gender which in Hebrew determines noun–adjective agreement.

Parent report instruments adapted from the MacArthur-Bates Communicative Development Inventories (CDI) examined vocabulary development in children aged 0 ; 8 to 2 ; 6 for two Chinese languages, Mandarin (n=1694) and Cantonese (n=1625). Parental reports suggested higher overall scores for Mandarin- than for Cantonese-speaking children from approximately 1 ; 4 onward. Factors relevant to the difference were only-child status, monolingual households and caregiver education. In addition to the comparison of vocabulary scores overall, the development of noun classifiers, grammatical function words common to the two languages, was assessed both in terms of the age and the vocabulary size at which these terms are acquired. Whereas age-based developmental trajectories again showed an advantage for Beijing children, Hong Kong children used classifiers when they had smaller vocabularies, reflecting the higher frequencies and greater precision of classifier use in adult Cantonese. The data speak to the importance of using not just age, but also vocabulary size, as a metric by which the acquisition of particular linguistic elements can be examined across languages.

Pragmatic development requires the ability to use linguistic forms, along with non-verbal cues, to focus an interlocutor's attention on a referent during conversation. We investigate the development of this ability by examining how the use of demonstratives is learned in Turkish, where a three-way demonstrative system (bu, şu, o) obligatorily encodes both distance contrasts (i.e. proximal and distal) and absence or presence of the addressee's visual attention on the referent. A comparison of the demonstrative use by Turkish children (6 four- and 6 six-year-olds) and 6 adults during conversation shows that adultlike use of attention directing demonstrative, şu, is not mastered even at the age of six, while the distance contrasts are learned earlier. This language specific development reveals that designing referential forms in consideration of recipient's attentional status during conversation is a pragmatic feat that takes more than six years to develop.

The validity of MLU and a measure of syntactic complexity were tested against LARSP on spontaneous speech samples from 87 children, ranging in age from 1;6 to 4;9. Change in some LARSP clausal measures was found across MLU stages up to MLU 4.5. For the measure of syntactic complexity, no such ceiling was found for the clausal connectivity score in LARSP or for average clausal complexity in LARSP. Neither MLU nor the measure of syntactic complexity indexed LARSP phrasal complexity. It is concluded that MLU is a valid measure of clausal complexity up to 4·5 and that our measure of syntactic complexity is more valid at more advanced stages.

This study evaluated the age-relationship, intra-sample reliability and grammatical validity of MLU-like measures of utterance length in the free speech of 21 normally developing children aged 1;8 to 2;8 with MLU between 1·05 and 3·06. Contrary to a previous study by Klee & Fitzgerald (1985). it was found that measures of utterance length hold a good relation with age, are reliable and predict grammatical development well in the age and MLU range considered. It is argued that there are identifiable points in the developmental evolution of MLU and MLU-like indices beyond which their reliability and validity have serious problems. Below these points, they constitute sound measures of syntactic development.