Previous studies show that young monolingual children's ability to ‘fast map’ new word forms is closely associated with both their age and existing vocabulary knowledge. In this study we investigate potential relationships between age, fast mapping skills and existing vocabulary knowledge in both languages of developing bilingual preschool children. Participants were twenty-six typically developing children, ages 3 ; 0 to 5 ; 3. All children learned Hmong as their primary home language (L1) and English as a second language (L2). Fast mapping and vocabulary knowledge tasks were administered in L1 and L2. For vocabulary knowledge, scores were comparable in L1 and L2; for fast mapping, scores were somewhat greater in L1 than L2. In contrast to previous findings with monolingual children, fast mapping performance was not related to age or existing vocabulary knowledge in either Hmong or English. There were, however, significant positive and negative cross-language correlations between L1 fast mapping and L2 vocabulary.

Studies examining factors that influence when words are learned typically investigate one lexical category or a small set of words. We provide the first evaluation of the relation between input frequency and age of acquisition for a large sample of words. The MacArthur-Bates Communicative Development Inventory provides norming data on age of acquisition for 562 individual words collected from the parents of children aged 0 ; 8 to 2 ; 6. The CHILDES database provides estimates of frequency with which parents use these words with their children (age: 0 ; 7–7 ; 5; mean age: 36 months). For production, across all words higher parental frequency is associated with later acquisition. Within lexical categories, however, higher frequency is related to earlier acquisition. For comprehension, parental frequency correlates significantly with the age of acquisition only for common nouns. Frequency effects change with development. Thus, frequency impacts vocabulary acquisition in a complex interaction with category, modality and developmental stage.

Rapid acquisition of linguistic categories or constructions is sometimes regarded as evidence of innate knowledge. In this paper, we examine Polish children's early understanding of an idiosyncratic, language-specific construction involving the instrumental case – which could not be due to innate knowledge. Thirty Polish-speaking children aged 2 ; 6 and 3 ; 2 participated in a elicited production experiment with novel verbs that were demonstrated as taking nouns in the instrumental case as patients. Children heard the verbs in sentences with either masculine or feminine nouns (which take different endings in the instrumental case), and were tested with new nouns of the same and of the opposite gender. In both age groups, a substantial majority of children succeeded in generalizing from one gendered form of the instrumental case to the other (especially to the masculine), thus indicating that they have some kind of abstract understanding of the instrumental case in this construction. This relatively early abstract knowledge of an idiosyncratic construction casts doubt on the view that early acquisition requires innate linguistic knowledge.

Young children learning English are biased to attend to the shape of solid rigid objects when learning novel names. This study seeks further understanding of the processes that support this behavior by examining a previous finding that three-year-old children are also biased to generalize novel names for objects made from deformable materials by shape, even after the materials are made salient. In two experiments, we examined the noun generalizations of 72 two-, three- and four-year-old children with rigid and deformable stimuli. Data reveal that three-year-old, but not two- or four-year-old, children generalize names for deformable things by shape, and that this behavior is not due to the syntactic context of the task. We suggest this behavior is an overgeneralization of three-year-old children's knowledge of how rigid things are named and discuss the implications of this finding for a developmental account of the origins of the shape bias.

Segmental distributions of Korean infant-directed speech (IDS) and adult-directed speech (ADS) were compared. Significant differences were found in both consonant and vowel patterns. Korean-speaking mothers using IDS displayed more frequent labial consonantal place and less frequent coronal and glottal place and fricative manner. They showed more use of mid and low central vowels in IDS as well as more use of language-specific Korean phonemes. Mothers produced significantly more fortis and geminate and less lenis consonant phonemes in IDS than in ADS. Findings suggest that Korean mothers speaking to infants in the IDS speech style use sounds that more closely match infant production propensities as well as highlighting perceptually salient properties. IDS may serve to facilitate infant learning of ambient language phonological regularities.

The main objective of this paper is to describe the trajectory of Danish children's early lexical development relative to other languages, by comparing a Danish study based on the Danish adaptation of The MacArthur-Bates Communicative Development Inventories (CDI) to 17 comparable CDI-studies. The second objective is to address the feasibility of cross-linguistic CDI-comparisons. The main finding is that the developmental trend of Danish children's early lexical development is similar to trends observed in other languages, yet the vocabulary comprehension score in the Danish children is the lowest across studies from age 1 ; 0 onwards. We hypothesize that the delay is related to the nature of Danish sound structure, which presents Danish children with a harder task of segmentation. We conclude that CDI-studies are an important resource for cross-language studies, but reporting of studies needs to be standardized and the availability of published data improved in order to make comparisons more straightforward.

This paper presents a large-scale cross-sectional study of Danish children's early language acquisition based on the Danish adaptation of the MacArthur-Bates Communicative Development Inventories (CDI). Measures of validity and reliability imply that the Danish adaptation of the American CDI has been adjusted linguistically and culturally in appropriate ways which makes it suitable for tapping into Danish children's language acquisition. The study includes 6,112 randomly selected children in the age of 0 ; 8 to 3 ; 0, and results related to the development of early gestures, comprehension and production of words as well as grammatical skills, are presented.

Two recent papers (de Villiers & Johnson, 2007; Johnson, de Villiers & Seymour, 2005) have claimed that children have difficulty with verbal -s until five–six-years-old. This contrasts with perceptual studies showing evidence for sensitivity to the grammatical properties of verbal -s as young as 1; 4. These apparently conflicting findings can be reconciled by differentiating between early perceptual grammatical knowledge and later semantic comprehension.

This article reviews the proliferation of terms that have been coined to denote the language environment of the young child. It is argued that terms are often deployed by researchers without due consideration of their appropriateness for particular empirical studies. It is further suggested that just three of the dozen or more available terms meet the needs of child language researchers in most instances: child-directed speech, infant-directed speech and exposurelanguage. The phenomena denoted by these terms are then considered. The term register is generally borrowed for this purpose from sociolinguistics. However, close inspection of this concept reveals that the notion of register needs to be constrained, in specified ways, in order to be of any real value within the field of child language research.

The Macarthur-Bates Communicative Development Inventories (CDI) have been used widely to document early communicative development. The paper reports on a large community sample of 1,447 children recruited from low, middle and high socioeconomic (SES) areas across metropolitan Melbourne, Australia. Regression analyses were conducted to determine the extent to which communicative behaviours reported at 0 ; 8 and 1 ; 0 predicted vocabulary development at 1 ; 0 and 2 ; 0. In support of previous findings with smaller, often less representative samples, gesture and object use at 1 ; 0 were better predictors of 2 ; 0 vocabulary than were gesture and object use at 0 ; 8. At 1 ; 0, children from the lower SES groups were reported to understand more words than children from the higher SES groups, but there were no SES differences for words produced at 1 ; 0 or 2 ; 0. The findings add to our understanding of the variability in the development of early communicative behaviours.

Children with word finding difficulties (CwWFDs) are slower and less accurate at naming monomorphemic words than typically developing children (Dockrell, Messer & George, 2001), but their difficulty in naming morphologically complex words has not yet been investigated. One aim of this paper was to identify whether CwWFDs are similar to typically developing children at producing inflected (morphologically complex) words. A second aim was to investigate whether the dual-mechanism model could account for the use of morphology in a sample of CwWFDs, exemplifying the notion that regular inflections are part of a rule-based system and computed on-line, while irregular inflections are retrieved directly from the associative system (Pinker, 1999). The inflectional knowledge of a group of CwWFDs was compared against a group of language age-matched typically developing peers in three experiments. In Experiment 1 children produced the past tenses of high- and low-frequency regular and irregular English verbs. In Experiment 2 children generalized their knowledge of the past tense system onto nonsense verbs and in Experiment 3 children produced past tenses of verbs used in either a denominal or a verb root context. In each of these three studies, the CwWFDs performed similarly to matched typical children, suggesting that they do not have a selective problem with morphosyntactic features of words. The findings provide mixed support for the dual-mechanism model.