This study measured longitudinal change in six parameters of infant utterances (i.e. number of sounds, CV syllables, supraglottal consonants, and repetitions per utterance, temporal duration, and seconds per sound), investigated previously unexplored characteristics of repetition (i.e. number of vowel and CV syllable repetitions per utterance) and analyzed change in vocalizations in relation to age and developmental milestones using multilevel models. Infants (N=18) were videotaped bimonthly during naturalistic and semi-structured activities between 0 ; 3 and the onset of word use (M=11·8 months). Results showed that infant utterances changed in predictable ways both in relation to age and in relation to language milestones (i.e. reduplicated babble onset, word comprehension and word production). Looking at change in relation to the milestones of language development led to new views of babbling, the transition from babbling to first words, and processes that may underlie these transitions.

The objectives were to explore the often reported noun advantage in children's language acquisition using a picture naming paradigm and to explore the variables that affect picture naming performance. Participants in Experiment 1 were aged three and five years, and in Experiment 2, five years. The stimuli were action and object pictures. In Experiment 1, action pictures produced more errors than object pictures for the three-year-olds, but not the five-year-olds. A qualitative analysis of the errors revealed a somewhat different pattern of errors across age groups. In Experiment 2 there was no robust difference in accuracy for the actions and objects but naming times were longer for actions. Across both experiments, imageability was a robust predictor of object naming performance, while spoken frequency was the most important predictor of action naming. The results are discussed in terms of possible differences in the manner in which nouns and verbs are acquired.

Caregiver speech is not a static collection of utterances, but occurs in conversational exchanges, in which caregiver and child dynamically influence each other's speech. We investigate (a) whether children and caregivers modulate the prosody of their speech as a function of their interlocutor's speech, and (b) the influence of the initiator of the conversation on durational characteristics of the exchange. We analyzed naturalistic conversations from 13 mother–infant/toddler dyads aged 12–30 months across full-day recordings of 3–5 days per dyad using LENA and automated analytic tools. We found small, but significant, effects of mothers and their children influencing each other's speech, particularly in pitch measures. We also found longer utterances and shorter response latencies for the initiator of a conversation. While mothers show more mature conversational capabilities (more entrainment, shorter response latencies), our findings converge with prior research to highlight the active role of young children in the conversational exchange.

The first 50 words of three blind children were collected and analysed using procedures used by Nelson (1973) on 18 sighted children. The early vocabulary of the blind children paralleled that of the sighted children in the age and speed of acquisition, and in the underlying characteristics of what the children chose to label. These reflect a sensorimotor organization in which self-action and perceptual change are the salient variables. The early words of the blind children differed from those of sighted children in the percentage of words in each of Nelson's grammatical categories. This suggests differences in how the children use language. These differences are discussed as a function of the children's lack of vision and their particular language learning context.

The evidence for the Contrastive Hypothesis (Clark 1980, 1983a, b, 1987, Barrett 1978, 1982) is reviewed. An examination of data from the acquisition of object words, relational words and superordinate terms reveals little support for this hypothesis that young children automatically assume that every two words in their lexicons contrast. Further, theoretical problems with the positions that children assign words to semantic fields as they are acquiring them and that innovations are used to fill lexical gaps make these stances untenable.

In this study, we use corpus analysis and computational modelling techniques to compare two recent accounts of the OI stage: Legate & Yang's (2007) Variational Learning Model and Freudenthal, Pine & Gobet's (2006) Model of Syntax Acquisition in Children. We first assess the extent to which each of these accounts can explain the level of OI errors across five different languages (English, Dutch, German, French and Spanish). We then differentiate between the two accounts by testing their predictions about the relation between children's OI errors and the distribution of infinitival verb forms in the input language. We conclude that, although both accounts fit the cross-linguistic patterning of OI errors reasonably well, only MOSAIC is able to explain why verbs that occur more frequently as infinitives than as finite verb forms in the input also occur more frequently as OI errors than as correct finite verb forms in the children's output.

Multivariate genetic analysis was used to examine the genetic and environmental aetiology of the interrelationships of diverse linguistic skills. This study used data from a large sample of 4½-year-old twins who were tested on measures assessing articulation, phonology, grammar, vocabulary, and verbal memory. Phenotypic analysis suggested two latent factors: articulation (2 measures) and general language (the remaining 7), and a genetic model incorporating these factors provided a good fit to the data. Almost all genetic and shared environmental influences on the 9 measures acted through the two latent factors. There was also substantial aetiological overlap between the two latent factors, with a genetic correlation of 0·64 and shared environment correlation of 1·00. We conclude that to a large extent, the same genetic and environmental factors underlie the development of individual differences in a wide range of linguistic skills.

In this paper we report on a visual world eye-tracking experiment that investigated the differing abilities of adults and children to use referential scene information during reanalysis to overcome lexical biases during sentence processing. The results showed that adults incorporated aspects of the referential scene into their parse as soon as it became apparent that a test sentence was syntactically ambiguous, suggesting they considered the two alternative analyses in parallel. In contrast, the children appeared not to reanalyze their initial analysis, even over shorter distances than have been investigated in prior research. We argue that this reflects the children's over-reliance on bottom-up, lexical cues to interpretation. The implications for the development of parsing routines are discussed.

Comprehension of metaphor in preschoolers was studied through an elicited repetition task. Subjects were 52 children aged 3;0 to 5;2. Repetition performance on metaphors was compared to repetitions of semantically well-formed literal sentences as well as semantically anomalous sentences, all matched for length, vocabulary and sentence structure. Accuracy on literal and metaphoric stimuli was comparable, and both were significantly better than performance on anomalous sentences. There were no effects for age or sex. It was shown that the metaphors were not semantically anomalous to the children and that they were processed on a par with literal language. The argument is advanced from a review of the literature that imitation implicates understanding of the material imitated. If metaphor is thus shown to emerge early in the child's linguistic repertory, figurative language, it may be argued, occupies a more central position in linguistic theory than it has been accorded.

Deficits in pragmatic language are central to autism spectrum disorder (ASD). Here we investigate common ground, a pragmatic language skill in which speakers adjust the contents of their speech based on their interlocutor's perceived knowledge, in adolescents with ASD and typical development (TD), using an experimental narrative paradigm. Consistent with prior research, TD participants produced shorter narrations when they shared knowledge with an interlocutor, an effect not observed at the group level in ASD. This effect was unrelated to general skills such as IQ or receptive vocabulary. In ASD, the effect was correlated with age and symptom severity: older and less severely affected participants did shorten their narratives. Several metrics (including explicit references to common ground, speech disfluencies, and communicative quality ratings) suggested that, although adolescents with ASD did not show implicit reductions in their narrative length, they were aware of common ground, and communicated differently in its presence.

Young children's competence in using and responding to clarification requests may reflect their desire to achieve goals through the direction of others rather than knowledge that messages must be understood by another mind. This possibility was addressed by examining miscommunication episodes between children aged 2;6 and their parents in videotaped free play sessions. Although the children generally responded appropriately in form to parental clarification requests, they responded more often to and resolved successfully more of those following their own requests than those following their assertions. Thus, the results support the idea that young children are frequently motivated to repair their utterances when they have not achieved some overt behaviour desired from others. These findings are discussed in the light of the conversational experience two-year-olds bring to clarification situations.

A longitudinal diary-and-videotape study of the production of phonological segments by a Spanish—English bilingual child, age 1;6–4;6, revealed a consistent separation of the phonological systems of the two languages from the earliest period, with minimal interference at later times. These results are in contrast to results obtained from another child in a similar study (Schnitzer & Krasinski, 1994). The relevance of these data to the issue of whether bilingual children first use a single system before acquiring two discrete languages is discussed, as is the general question of how to interpret the early phonological production of bilinguals.

Twenty-four infants at 1 ; 1 and their mothers were videotaped for 18 minutes while playing. Infants' pointing, reaching and object-extending gestures were coded in three communicative intent contexts: proto-declarative, or commenting; proto-imperative, or requesting; and ambiguous. Mothers' responses to infants' gestures were coded as object labels, action labels, internal state labels and non-labeling utterances. Infants most often pointed in the proto-declarative and used object extensions in the proto-imperative context. Infants produced pointing and reaching equivalently in the ambiguous context. Mothers' responses included object labels more often in response to points than object extensions. In contrast, mothers provided action labels most often in response to object extensions. Mothers produced large proportions of internal state labels, although the type varied by gesture. Results suggest mothers' labels following infants' gestures may serve as a mechanism for vocabulary acquisition and internal state understanding.

Is parental report of comprehension valid for individual words? If so, how well must an infant know a word before their parents will report it as ‘understood’? We report an experiment in which parental report predicts infant performance in a referent identification task at 1 ; 6. Unlike in previous research of this kind (i.e. Houston-Price, Mather & Sakkalou, 2007), infants saw items only once, and image pairs were taxonomic sisters. The match between parental report and infant behaviour provides evidence of the item-level accuracy of both measures of lexical comprehension, and informs our understanding of how British parents interpret standardized Communicative Development Inventories (CDIs).

Studies based on naturalistic data are a core tool in the field of language acquisition research and have provided thorough descriptions of children's speech. However, these descriptions are inevitably confounded by differences in the relative frequency with which children use words and language structures. The purpose of the present work was to investigate the impact of sampling constraints on estimates of the productivity of children's utterances, and on the validity of error rates. Comparisons were made between five different sized samples of wh-question data produced by one child aged 2;8. First, we assessed whether sampling constraints undermined the claim (e.g. Tomasello, 2000) that the restricted nature of early child speech reflects a lack of adultlike grammatical knowledge. We demonstrated that small samples were equally likely to under- as overestimate lexical specificity in children's speech, and that the reliability of estimates varies according to sample size. We argued that reliable analyses require a comparison with a control sample, such as that from an adult speaker. Second, we investigated the validity of estimates of error rates based on small samples. The results showed that overall error rates underestimate the incidence of error in some rarely produced parts of the system and that analyses on small samples were likely to substantially over- or underestimate error rates in infrequently produced constructions. We concluded that caution must be used when basing arguments about the scope and nature of errors in children's early multi-word productions on analyses of samples of spontaneous speech.

Nativist and constructivist accounts differ in their characterization of children's knowledge of grammatical categories. In this paper we present research on the process of acquisition of a particular grammatical system, gender agreement in the Spanish noun phrase, in children under three years of age. The design of the longitudinal study employed presents some variations in relation to classical studies. The aim was to obtain a large corpus of NP data which would allow different types of analysis of the children's productions to be carried out. Intra-individual variability in early NP types was analyzed and measured, and an elicitation task for adjectives was used. Results show that the acquisition of NP and gender agreement is a complex process which advances as the children gradually integrate different pieces of evidence: phonological, distributional and functional. The reduction of variability as the grammatical process advances is a key feature for its explanation.

Macken & Barton (1980) noted an asymmetry in their young Spanish-learning children's word-initial stop productions, as compared with English-learning children's, namely, ‘the Spanish-learning children acquire “lead” voicing…after age four’, whereas ‘English-learning children acquire “long lag” stops…by about 2;6’. ‘One possible explanation’, they propose, ‘is that lead voicing is inherently difficult to produce or at least more difficult to learn than long lag…’. The purpose of this Note is to present data suggesting that young children learning French, which also employs phonetically pre-voiced stops for its phonemically voiced category, also show an asymmetry in their word-initial stop productions. Furthermore, this asymmetry supports the notion, proposed by Macken & Barton, that lead voicing is somehow ‘more difficult’ for these young children to learn to produce. However, the actual ‘strategy’ used by the French-learning children to circumvent this presumed difficulty is different from that used by Macken & Barton's Spanish-learning children. This difference supports the notion that children have a certain degree of latitude in finding their way through the maze of psycholinguistic development (Kiparsky & Menn 1977).

This paper investigates developmental changes, as well as inter-linguistic and inter-individual variations, in the expansion and composition of French children's early lexicons. Two studies were conducted using children's naturalistic productions: a longitudinal study of one child between 1;2 and 2;6, and a cross-sectional study of two groups (12 children each) aged 1;8 and 2;6. Analyses indicate that lexical productivity (measured in types, tokens, and new words) strongly increased with age, whereas lexical diversity showed almost no developmental progression. Nouns and para-lexical elements (including interjections, fillers or formulas) were predominant until 1;8 and decreased over time, while predicates and grammatical words increased. As compared to English, French development was characterized by less frequent nouns, initially more frequent predicates, and a remarkable expansion of grammatical words. Inter-individual variability in lexical productivity, in lexical diversity, and in the proportions of different categories was more marked at 1;8 than at 2;6. Lexical profiles found at 1;8 suggest the existence of more diversified organizational patterns than those captured in the referential-expressive distinction.

The study was designed to investigate 2-month-old infant preferential attention to a feature found to be characteristic of mothers' speech to their infants. A modified infant-control auditory preference paradigm was employed to assess infants' differential attention to synthetically generated and naturally produced rising and falling intonation contours. Analysis of these data revealed that the infants attended more to the rising naturally produced intonation contour. A reverse pattern of greater attention to the falling contour was found with the synthetically generated stimuli. In addition, inspection of the results permitted the conclusion that the infant-control preference paradigm was a viable method for assessing the 2-month-old infant's preferential attention to auditory stimuli. The results are discussed in terms of their relevance to the study of the infant's developing language reception abilities.

Some authors have suggested that definitional skills include metalinguistic components (Watson, 1985; Snow, 1990; McGhee-Bidlack, 1991). The present study therefore empirically investigated relations between the ability to define words and level of metalinguistic awareness in 280 Italian children (with ages ranging from 5 to 11 years) and in two groups of 40 adults each (with low and high educational levels, respectively). We used a definitional task presenting 24 terms (nouns, verbs, and adjectives, which were either concrete or abstract) and a task examining 6 different aspects of metalinguistic awareness. Our aim was to demonstrate that metalinguistic skills can positively predict the formal quality of definitions and to identify various aspects of metalinguistic skills that might be directly related to definitional skills. Results showed better performance on both tasks as a function of age and educational level; they also confirmed the important roles of metalinguistic ability and educational level in producing well-structured formal definitions.