One of the most widely used indices of language development is a measure of utterance length in morphemes (MLUm). This study examines the applicability of MLUm to the acquisition of Irish. MLUm was calculated for data from Cian, aged 1;11–3;0. Even when an attempt was made to ‘assume the maximum’ by counting all possible morphemes, the correlation between a morpheme MLU (MLUm) and a word count MLU (MLUw) was very high (0·99). This points to MLUw being as effective a measure of Irish development as MLUm, as well as being easier to apply and more reliable. MLUw was calculated for the two younger children in the study (Eibhlís 1;4–2;1 and Eoin 1;10–2;6). An examination of the relationship between the three children's MLUw values and their grammatical complexity as measured on ILARSP (the Irish adaptation of LARSP) indicates that MLUw is a useful preliminary index for early development in Irish. However, further data are necessary to check whether MLUw loses its predictive relationship with grammatical complexity after a certain point. The study emphasizes the caution necessary in applying MLU to languages whose acquisition has not hitherto been studied, and underlines the role of MLU as a preliminary measure, which must not be overinterpreted.

Spontaneous speech samples from children during the period of transition from one word to multi-word utterances in interaction with their French-speaking mothers were explored in order to study the appearance and development of functional changes in their use of language. Two types of such change were noted in the longitudinal records of four children when they were still essentially one-word speakers: the beginnings of references to the past, and the appearance of explanations and justifications, especially in communicative situations of request and refusal. The co-appearance of these behaviours is discussed in relation to two more general developmental changes: a detachment from the immediately perceptible situation linked to a further elaboration of the signifier-signified relation, and a socio-cognitive development leading to a view of the interlocutor as an alter ego, as a person whose psychological states may be different from the child's own.

Mothers' speech in an identification task was examined for ten mother–child pairs in which the child's age varied from 1; 9 to 4; 9. Stimuli were used from three domains, animals, clothes and furniture. These varied in familiarity, centrality (goodness of exemplar) and number of items. Basic-level category terms were found to be the most frequently used labels. Superordinate category terms were elicited by (a) an unfamiliar animal and (b) groups of items from the same domain. Information on category relations was provided in several ways: alternative labels, multiple labels and explicit statements of inclusion. Competencies required to learn the correct referent for category terms and differences among superordinate categories are discussed.

Grammatical inflections such as the English plural noun -s and third person singular verb -s are acquired at different points in time by young children. This finding is typically attributed to factors such as relative semantic salience or the distinction between lexical and functional categories. In this study input frequency, sentence position, and duration were examined as possible contributing factors. In both conversations with and stories aimed at young children, noun plural inflections were found to be more frequent than third singular verb inflections, especially in sentence-final position. Analysis of the speech of four mothers reading stories to their two-year-old children confirmed that duration differences also exist in the input. Because fricatives were lengthened in sentence-final position and plural nouns were much more likely to appear in these positions than were third singular verb forms, plural nouns were significantly longer than third singular inflections on average. The possible implications of these findings for language learnability theories and accounts of grammatical deficits in specific language impairment are discussed.

The fundamental frequency F0 patterns of maternal speech addressed to infants aged 0;3–0;4 were measured quantitatively. Speech samples were recorded when six Japanese-speaking mothers addressed an adult and their own infants. Japanese mothers speaking to adults use a relatively restricted F0 range, concentrated around the mother's F0, which tends to be near the low end of the total range used. These acoustic characteristics are not altered substantially when these same women speak to their infants in initial utterances to attract the infants' attention. If such attempts are unsuccessful, however, they are likely to make more exaggerated utterances, in which F0 shifts upward and the frequency range is significantly increased. Moreover, only when acoustic characteristics of maternal speech to infants are exaggerated, can the type of F0 contour of the infant's subsequent response be predicted to a significant extent from the mother's preceding utterance.

This study investigated the development of knowledge about the presuppositions of cognitive verbs that take sentential complements. The verbs included factives, which presuppose the truth of their complements, and nonfactives, which carry no such presupposition. Three tasks assessed children's ability to (a) assign truth values to complements according to the presuppositions of the main verbs; (b) select verbs to describe people's mental states; and (c) state the presuppositions of the verbs in definitions. The results indicated that the presuppositions of the factives know, forget, and remember and the nonfactive think are not learned until age 4. Believe, which has factive and nonfactive properties, is mastered after age 7. The children's performance differed across tasks due to variations in processing requirements.

A brief theoretical statement on definition is advanced, followed by a study of the development of definition in children aged 5;0–10;0. The empirical findings suggest that the emergence of superordinate terms in definition cannot be adequately accounted for simply by appeal to changes in underlying knowledge, or to selectional restrictions on the structure of the definiens. Rather, the development of definition can best be characterized as the gradual articulation of a conventional definitional form out of the more general forms of ordinary oral discourse. It is suggested that definitions are expressions of word meaning that reflect the unique requirements of a literate register, and that the increasing dominance of superordinate terms in definitions reflects in part the adoption of this conventional form of expression.

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.

Variations in the amount and nature of early language to which children are exposed have been linked to their subsequent ability (e.g. Huttenlocher, Haight, Bryk, Seltzer & Lyons, 1991; Hart & Risley, 1995). In three computational simulations, we explore how differences in linguistic experience can explain differences in word learning ability due to changes in the development of semantic category structure. More specifically, we manipulate the amount of language input, sentential complexity, and the frequency distribution of words within categories. In each of these simulations, improvements in category structure, are tightly correlated with subsequent improvements in word learning ability even when the nature of the input remains the same over time. These simulations suggest that variation in early language environments may result in differences in lexical proficiency by altering underlying cognitive abilities like categorization.

This paper presents a proposed strategy of phonology based on acquisition data from two children, one French and one English. Both children showed a process of FRONTING, where the sounds in the child's words are ordered from those produced at the front of the mouth to those produced in the back. While this first appears to be an uncommon strategy, an examination of its implied universals suggests that Fronting at some more basic level may represent a general phonological process. Specifically, Fronting suggests that a marked or unmarked relationship exists between the initial and final consonants of a CVC syllable dependent upon their adherence to Fronting. It is proposed that back consonants are less marked in syllable final position than initial position and vice versa for front consonants. Thus Jakobson's theory, based on markedness in initial consonants, is just part of a more general phenomenon of markedness in syllables. Data are given that suggest that such is the case.

The present research investigated whether children's referential choices for verb arguments are motivated by pragmatic features of discourse referents across different developmental stages, not only for children learning null argument languages but also for those learning overt argument languages. In Study 1, the form (null, pronominal, or lexical) and referential status (given or new) of verb arguments were systematically analysed in six English-speaking and six Japanese-speaking children and their mothers when the children were at 1;9 and 3;0. In Study 2, non-linguistic pragmatic correlates (pointing, reaching, moving, making a head motion, or purposeful gaze direction toward a referent) were analysed in addition to the form and referential status of arguments at each of four linguistic periods between MLU 1·00 and 4·00 in two English-speaking and two Japanese-speaking children and their mothers. The results revealed that, when both linguistic and non-linguistic referential behaviours were considered, the English-speaking children showed patterns consistent with language-universal as well as language-specific discourse-pragmatic principles by 2;0 (between MLU 2·00 and 2·99), whereas the Japanese-speaking children did not show these patterns even as late as 3;0 (MLU 4·00 and above). Results also indicated that the children who were exposed to more consistent discourse-pragmatic referential patterns from their input tended to show these patterns earlier than those exposed to inconsistent patterns. Together these findings suggest that both the referential status of discourse referents as well as parental input predict children's referential choices across typologically different languages.

Twenty mothers' provision of responsive, supportive behavioural directive, and intrusive behavioural and attentional directive speech was investigated during interactions with their children at ages 0 ; 10, 1 ; 1, 1 ; 5 and 1 ; 9 in two natural contexts, free play and bathtime. Issues examined included developmental change, contextual differences, consistency across contexts and stability over time. Analyses revealed increases in frequencies of maternal responsive and supportive directive utterances and decreases in maternal intrusive directives with age. Differences between contexts included more speech and supportive directiveness during play than bath. Responsiveness and intrusive attentional directiveness demonstrated considerable consistency and stability. Mothers provided greater responsiveness to girls than to boys, but more intrusive directives to boys than to girls. Mothers' production of supportive and intrusive directives was unrelated, and their rates of responsive speech were inversely associated with their rates of intrusive directive speech, highlighting the importance of distinguishing between supportive and intrusive directiveness.

A longitudinal diary-and-videotape study of the production of phonological segments by a Spanish–English bilingual child, age 1;1–3;9, revealed four stages in consonantal acquisition: presystematic variation, formation of a single system, separation into two systems corresponding to the two languages, and achievement of adult target values with later interference of one language in the other. Vocalic acquisition proceeded with widespread variation, followed by stabilization at target adult values, without any apparent intermediate unitary-system stage. Relevance of the data adduced here to the issue of whether bilingual children first function with a single system before acquiring two discrete languages is discussed. The issue of what it may mean to have one or two systems of phonology is addressed.

This study investigated overextensions in comprehension and production using a new method (the preferential-looking paradigm) in which children (N = 99, mean age (younger) = 1;9, mean age (older) = 2;3) were asked to find the referent that matched the label they were given. Both Real Referent (in which there was a match) and Anomalous (in which there was no match) trials were included, as well as nonverbal control trials. During the Real Referent trials, all children significantly preferred the matching puppet. During the Anomalous trials, children showed no preference with two of the labels (dog and cat); however, they did show a preference when ‘cow’ was requested but not available. There were no differences based on prior overextension performance in production. It is concluded that overextensions in production are not diagnostic of children's underlying semantic representations, and that anomalous trials in comprehension provide useful information concerning young children's lexical entries.

This study investigated the degree to which cue validity, as estimated from textual analyses, predicts the actual strength of grammatical cues as they are used by speakers of Hebrew. An experiment was conducted to determine the differential strengths of the linguistic cues employed by Hebrew speakers when assigning the role of patient in sentences. Monolingual Hebrew-speaking subjects 4, 5, 7, and 9 years old, as well as adults, were tested using a sentence-picture verification task. Six cues were included in the study: word order, the accusative object marker, the reflexive noun phrase and three verbal derivations. By presenting subjects with sentences which set these cues in competition with one another, a measure of the strength of each cue was obtained. The results of a regression analysis revealed strong positive correlations between estimated cue validities and actual cue strengths for all but the youngest age groups. These results were interpreted as suggesting that cue validity is highly predictive of actual cue strengths. In addition, the strengths of the six cues varied as a function of the subject's age. Two additional factors were hypothesized to account for the performance of the older subjects: increased sensitivity to the reliability of cues and discourse-based constraints.

This report describes a perceptual study on the ability of mothers to perceptually differentiate cry samples elicited by three different stimulus situations. In some instances mothers were evaluating cries produced by their own infant; in other cases they judged those produced by infants with whom they were unfamiliar. The results of the investigation indicated that the eighteen mothers were generally unable to successfully match the cry samples with the three cry-evoking situations. Further, no differential advantage was found when mothers were judging samples produced by their own infant.

Although preschoolers typically accept the basic level label for an object (e.g. dog) and tend to resist all others (e.g. collie, animal), this tendency is not inviolable. Under certain circumstances, children accept more than one label per object. In this experiment, with 20 three- and 20 four-year-old children, we extended this body of research in three ways. We examined (1) children's production of multiple, hierarchically related labels; (2) the pragmatic consequences of the inherent asymmetry of inclusion relations; and (3) the influence of morphology (modifier + noun constructions vs. simple lexemes) at the subordinate level. Children labelled objects most frequently at the basic level, but also readily produced many non-basic level terms. Children, like adults, may prefer to label objects at the basic level, but they exhibit no general prohibition against also labelling at other, non-basic levels. Their performance challenges the notion that the ability to label objects flexibly at multiple levels is beyond the young child's capacity.

Language in autism has been the subject of intense interest, because communication deficits are central to the disorder, and because autism serves as an arena for testing theories of language acquisition. High-functioning older children with autism are often considered to have intact grammatical abilities, despite pragmatic impairments. Given the heterogeneity in language skills at younger ages, this assumption merits further investigation. Participants with autism (n=21, aged nine to seventeen years), matched on chronological age, receptive vocabulary and IQ, to 22 typically developing individuals, completed a grammaticality judgment task. Participants with autism were significantly less sensitive than controls, specifically for third person singular and present progressive marking. Performance interacted with sentence length, with lower sensitivity to errors occurring at the end of the longest stimulus sentences. Performance sensitivity was associated with onset of single word and phrase speech, and with severity of autistic symptomatology. Implications of findings are discussed.

Do infants and young children (two-year-olds) possess an implicit theory of mind which is revealed through their communicative interactions or are they simply treating their interlocutors as objects to manipulate in service to their own material ends? Shatz & O'Reilly (1990) criticized a paper by Golinkoff (1986) for claiming that infants were attempting to communicate as opposed to simply manipulate their listeners. This paper takes exception to that argument. It reviews additional evidence which indicates that infants in the second year of life are capable of communicating for the sake of the ‘meeting of minds’. The alternative – treating young children's communications as only the firing off of conversational routines for the purpose of attaining material ends – seriously underestimates infants' knowledge of the communicative process.

On some views of language, when one uses a term to describe or label an object, a contrast is always implied. However, there is an important difference between nouns and adjectives in their contrastive use: adjectives imply a contrast between members of a single noun category, whereas nouns do not imply a contrast between members of a single adjective category. For example, describing a car as new suggests a contrast with other cars. However, labelling it as a car does not as clearly imply a contrast with other new objects. There is no logical necessity for this distinction – it is not captured by the literal meanings of words. Yet it is a conceptual distinction implicit in the use of these terms. In two studies, we tested preschool children's appreciation for this conceptual distinction, using both familiar and unfamiliar words. In Study I, 4-year-olds (but not 3-year-olds) were able to disambiguate the meanings of simple nouns and adjectives by assuming that the adjectives, unlike the nouns, implied a contrast between category members. In Study II, children selected pictures to match totally novel adjectives and nouns (e.g. the fep one, the skub). Relying on part of speech alone, they interpreted these unfamiliar nouns and adjectives differently. Implications for children's use of referential language and word-learning strategies are discussed.