A speech act approach to the transition from pre-linguistic to linguistic communication is adopted in order to consider language in relation to behaviour generally and to allow for an emphasis on the USE of language rather than on its form. The structure of language is seen as non-arbitrary in that it reflects both attention structures (via predication) and action structures (via the fundamental case grammatical form of language). Linguistic concepts are first realized in action. A pilot study focusing on the regulation of JOINT attention and JOINT activity within the context of mutuality between mother and infant is discussed, with emphasis on ritualization in mutual play as a vehicle for understanding the development of the formal structures of language.

The achievement of labelling was investigated in a longitudinal study of one mother–infant dyad, using video-recordings of their free play in a period between 0; 8 and 1; 6. Analysis of joint picture-book reading revealed that this activity had very early on the structure of a dialogue. The child's lexical labels might be regarded as more adult-like substitutes for earlier communicative forms that he had utilized in the dialogue. These were smiling, reaching, pointing and babbling vocalizations, all of which were consistently interpreted by the mother as expressing the child's intention of requesting a label or providing one. Participating in a ritualized dialogue, rather than imitation, was found to be the major mechanism through which labelling was achieved.

The extant literature includes conflicting assertions regarding the influence of bilingualism on the rate of language development. The present study compared the language development of equivalently high-SES samples of bilingually and monolingually developing children from 1 ; 10 to 2 ; 6. The monolingually developing children were significantly more advanced than the bilingually developing children on measures of both vocabulary and grammar in single language comparisons, but they were comparable on a measure of total vocabulary. Within the bilingually developing sample, all measures of vocabulary and grammar were related to the relative amount of input in that language. Implications for theories of language acquisition and for understanding bilingual development are discussed.

This study compares the prosodie modifications in mothers' and fathers' speech to preverbal infants in French, Italian, German, Japanese, British English, and American English. At every stage of data collection and analysis, standardized procedures were used to enhance the comparability across data sets that is essential for valid cross-language comparison of the prosodie features of parental speech. In each of the six language groups, five mothers and five fathers were recorded in semi-structured home observations while speaking to their infant aged 0; 10–1;2 and to an adult. Speech samples were instrumentally analysed to measure seven prosodic parameters: mean fundamental frequency (f0), f0-minimum, f0-maximum, f0-range, f0-variability, utterance duration, and pause duration. Results showed cross-language consistency in the patterns of prosodic modification used in parental speech to infants. Across languages, both mothers and fathers used higher mean-f0, f0-minimum, and f0-maximum, greater f0-variability, shorter utterances, and longer pauses in infant-directed speech than in adult-directed speech. Mothers, but not fathers, used a wider f0-range in speech to infants. American English parents showed the most extreme prosodic modifications, differing from the other language groups in the extent of intonational exaggeration in Speech to infants. These results reveal common patterns in caretaker's use of intonation across languages, which may function developmentally to regulate infant arousal and attention, to communicate affect, and to facilitate speech perception and language comprehension. In addition to providing evidence for possibly universal prosodic features of speech to infants, these results suggest that language-specific variations are also important, and that the findings of the numerous studies of early language input based on American English are not necessarily generalisable to other cultures.

During the first eighteen months of life, infants acquire and refine a whole set of new motor skills that significantly change the ways in which the body moves in and interacts with the environment. In this review article, I argue that motor acquisitions provide infants with an opportunity to practice skills relevant to language acquisition before they are needed for that purpose; and that the emergence of new motor skills changes infants' experience with objects and people in ways that are relevant for both general communicative development and the acquisition of language. Implications of this perspective for current views of co-occurring language and motor impairments and for methodology in the field of child language research are also considered.

This study sought to determine why American parents from different socioeconomic backgrounds communicate in different ways with their children. Forty-seven parent–child dyads were videotaped engaging in naturalistic interactions in the home for ninety minutes at child age 2 ; 6. Transcripts of these interactions provided measures of child-directed speech. Children's vocabulary comprehension skills were measured using the Peabody Picture Vocabulary Test at 2 ; 6 and one year later at 3 ; 6. Results indicate that: (1) child-directed speech with toddlers aged 2 ; 6 predicts child vocabulary skill one year later, controlling for earlier toddler vocabulary skill; (2) child-directed speech relates to socioeconomic status as measured by income and education; and (3) the relation between socioeconomic status and child-directed speech is mediated by parental knowledge of child development. Potential mechanisms through which parental knowledge influences communicative behavior are discussed.

Verb learning is clearly a function of observation of real-world contingencies; however, it is argued that such observational information is insufficient to account fully for vocabulary acquisition. This paper provides an experimental validation of Landau & Gleitman's (1985) syntactic bootstrapping procedure; namely, that children may use syntactic information to learn new verbs. Pairs of actions were presented simultaneously with a nonsense verb in one of two syntactic structures. The actions were subsequently separated, and the children (MA = 2;1) were asked to select which action was the referent for the verb. The children's choice of referent was found to be a function of the syntactic structure in which the verb had appeared.

The study of language acquisition underwent a major revolution in the late 1950s as a result of the dissemination of technology permitting high-quality tape-recording of children in the family setting. This new technology led to major breakthroughs in the quality of both data and theory. The field is now at the threshold of a possible second major breakthrough stimulated by the dissemination of personal computing. Researchers are now able to transcribe tape-recorded data into computer files. With this new medium it is easy to conduct global searches for word combinations across collections of files. It is also possible to enter new codings of the basic text line. Because of the speed and accuracy with which computer files can be copied, it is now much easier to share data between researchers. To foster this sharing of computerized data, a group of child language researchers has established the Child Language Data Exchange System (CHILDES). This article details the formation of the CHILDES, the governance of the system, the nature of the database, the shape of the coding conventions, and the types of computer programs being developed.

The speech of two mothers to their infants at several points between three and eighteen months of age was analysed. Simplicity of the speech, as measured by MLU, was about the same at all ages, and none of the other features of the mothers' speech style showed any abrupt change at the time the children started to talk. The changes that did occur started much earlier, at about seven months. These findings are incompatible with the explanation that mothers speak simply and redundantly in response to cues of attention and comprehension from the child listener. It is suggested that the mothers interacted with their infants using a conversational model, and that the changes in the mothers' speech reflect their children's growing ability to function as conversational partners.

Lists of the first 50 words comprehended and produced by eight infants between 0; 9 and 1; 8 were compared. Comprehension development began earlier (around 0; 9) and reached the 50-word level (age 1; 1) earlier than production development (ages 1; 0 and 1; 6 respectively) and rate of word acquisition for comprehension was twice that of production, confirming the hypothesis that comprehension precedes production for lexical development. Word-class analysis revealed differences in the proportion and type of action words in comprehension and production vocabularies. It is suggested that action is central to lexical development but is expressed differently in comprehension, where action words are used to initiate actions, and production, where non-action words accompany the child's actions.

A new method to assess language comprehension in infants and young children is introduced in three experiments which test separately for the comprehension of nouns, verbs, and word order. This method requires a minimum of motor movement, no speech production, and relies on the differential visual fixation of two simultaneously presented video events accompanied by a single linguistic stimulus. The linguistic stimulus matches only one of the video events. In all three experiments patterns of visual fixation favour the screen which matches the linguistic stimulus. This new method may provide insight into the child's emerging linguistic capabilities and help resolve longstanding controversies concerning language production versus language comprehension.

Several recent studies have demonstrated strong relationships between lexical acquisition and subsequent developments within the domain of morphosyntax. A connectionist model of the acquisition of a morphological System analogous to that of the English past tense (Plunkett & Marchman, 1993) suggests that growth in vocabulary size may relate to the onset of over-regularization errors. However, this model suggests that the relationships between vocabulary size and morphosyntactic development are non-linear. Incremental increases in the number of verbs to be learned result in qualitative shifts in the treatment of both previously learned and novel forms, but only after the size of the lexicon exceeds a particular level (i.e. reaches a ‘critical mass’). In this paper we present parental report data from an extensive study of English-speaking children aged 1;4 to 2;6 using the MacArthur Communicative Development Inventory: Toddler form (N = 1130). These data corroborate several findings from previous studies, including the early usage of unmarked verb stems and the correct production of irregular past tense forms. Further, we demonstrate support for the ‘critical mass’ view of the onset of over-regularization errors, focusing on continuity among lexical and morphological developments. In our view, these data suggest that these linguistic milestones may be paced by similar, if not identical mechanisms.

This research examines whether infants actively seek information from a speaker regarding the referent of the speaker's utterance. Forty-eight infants (in three age groups: 1;2–1;3, 1;4–1;5, and 1;6–1;7) heard novel labels for novel objects in two situations: follow-in labelling (the experimenter looked at and labelled the toy of the infant's focus) vs. discrepant labelling (the experimenter looked at and labelled a different toy than that of the infant's focus). Subsequently, half of the infants were asked comprehension questions (e.g. ‘Where's the peri?’). The other half were asked preference questions (e.g. ‘Where's the one you like?’), to ensure that their comprehension performance was not merely the result of preferential responding. The comprehension results revealed developmental change in both (a) infants' ability to establish new word-object mappings (infants aged 1;2–1;3 failed to establish stable word-object links even in follow-in labelling), and (b) infants' ability to pinpoint the correct referent during discrepant labelling (only infants aged 1;6–1;7 succeeded). Thus the period between 1;2 and 1;7 represents a time of change in infants' ability to establish new word-object mappings: infants are becoming increasingly adept at acquiring new labels under minimal learning conditions.

Results are reported for stylistic and developmental aspects of vocabulary composition for 1, 803 children and families who participated in the tri-city norming of a new parental report instrument, the MacArthur Communicative Development Inventories. We replicate previous studies with small samples showing extensive variation in use of common nouns between age o;8 and 1;4 (i.e. ‘referential style’), and in the proportion of vocabulary made up of closed-class words between 1;4 and 2;6 (i.e. ‘analytic’ vs. ‘holistic’ style). However, both style dimensions are confounded with developmental changes in the composition of the lexicon, including three ‘waves’ of reorganization: (1) an initial increase in percentage of common nouns from 0 to 100 words, followed by a proportional decrease; (2) a slow linear increase in verbs and other predicates, with the greatest gains taking place between 100 and 400 words; (3) no proportional development at all in the use of closed-class vocabulary between 0 and 400 words, followed by a sharp increase from 400 to 680 words. When developmental changes in noun use are controlled, referential-style measures do not show the association with developmental precocity reported in previous studies, although these scores are related to maternal education. By contrast, when developmental changes in grammatical function word use are controlled, high closed-class scores are associated with a slower rate of development. We suggest that younger children may have less perceptual acuity and/or shorter memory spans than older children with the same vocabulary size. As a result, the younger children may ignore unstressed function words until a later point in development while the older children tend to reproduce perceptual details that they do not yet understand. Longitudinal data show that early use of function words (under 400 words) is not related to grammatical levels after the 4OO-word point, confirming our ‘stylistic’ interpretation of early closed-class usage. We close with recommendations for the unconfounding of stylistic and developmental variance in research on individual differences in language development, and provide look-up tables that will permit other investigators to pull these aspects apart.

In a previous issue of this Journal, MacWhinney & Snow (1985) laid out the basic sketch for an international system for exchanging and analysing child language transcript data. This system – the Child Language Data Exchange System (CHILDES) – has developed three major tools for child language research: (1) the CHILDES database of transcripts, (2) the CHAT system for transcribing and coding data, and (3) the CLAN programs for analysing CHAT files. Here we sketch out the current shape of these three major tools and the organizational form of the CHILDES system. A forthcoming book (MacWhinney, in press) documents these tools in detail.

It is commonly thought that children learning two languages simultaneously during infancy go through a stage when they cannot differentiate their two languages. Virtually all studies of infant bilingual development have found that bilingual children mix elements from their two languages. These results have been interpreted as evidence for a unitary, undifferentiated language system (the unitary language system hypothesis). The empirical basis for these claims is re-examined and it is argued that, contrary to most extant interpretations, bilingual children develop differentiated language systems from the beginning and are able to use their developing languages in contextually sensitive ways. A call for more serious attention to the possible role of parental input in the form of mixed utterances is made.

The present study was conducted to assess the effect of didactic techniques used during storybook reading on young children's acquisition of new vocabulary introduced in storybooks. Thirty children for each group of three- and four-year-old children were read one storybook individually. The study included three storybook reading conditions: single-reading, repeated-reading and questioning. In both the repeated-reading and the questioning conditions, the storybook was read three times. Children in the questioning condition were asked, during each reading of the storybook, to label target items with the novel words. Listening to multiple readings of a storybook facilitated children's acquisition of expressive and receptive vocabulary, whereas answering questions during the multiple readings was more helpful to the acquisition of expressive than receptive vocabulary. These findings suggest that, under certain conditions, didactic techniques used by adults have differential effects on preschoolers' receptive and expressive vocabulary.

Universally, object names make up the largest proportion of any word type found in children's early lexicons. Here we present and critically evaluate a set of six lexical principles (some previously proposed and some new) for making object label learning a manageable task. Overall, the principles have the effect of reducing the amount of information that language-learning children must consider for what a new word might mean. These principles are constructed by children in a two-tiered developmental sequence, as a function of their sensitivity to linguistic input, contextual information, and social-interactional cues. Thus, the process of lexical acquisition changes as a result of the particular principles a given child has at his or her disposal. For children who have only the principles of the first tier (REFERENCE, EXTENDIBILITY, and OBJECT SCOPE), word learning has a deliberate and laborious look. The principles of the second tier (CATEGORICAL SCOPE, NOVEL NAME – NAMELESS CATEGORY’ or N3C, and CONVENTIONALITY) enable the child to acquire many new labels rapidly. The present unified account is argued to have a number of advantages over treating such principles separately and non-developmentally. Further, the explicit recognition that the acquisition and operation of these principles is influenced by the child's interpretation of both linguistic and non-linguistic input is seen as an advance.

The transition from slow to rapid word-learning was examined in a longitudinal study of 18 children. Beginning at age 1;2, mothers kept a diary of children's words. Diary entries were discussed during phone calls to the home every 2½ weeks. A chronological record of nouns and other word classes was coded from the diary records.

Thirteen children evidenced a prolonged period of up to three months during which rate of acquisition markedly increased. Almost threequarters of the words learned during this period were nouns. Five children evidenced more gradual word-learning, and acquired a balance of nouns and other word classes. These results suggest that the terms ‘vocabulary spurt’ and ‘naming explosion’ best describe children who focus their early linguistic efforts on a single strategy: learning names for things. Other children may attempt to encode a broad range of experience with a more varied lexicon, a strategy that results in more gradual lexical growth.

Analysing the gradual learning process through which a child becomes bilingual from early infancy, three stages can be distinguished: (1) the child has one lexical system which includes words from both languages; (2) the child distinguishes two different lexicons but applies the same syntactic rules to both languages; (3) the child has two linguistic codes, differentiated both in lexicon and in syntax, but each language is exclusively associated with the person using that language. Only at the end of this stage, when the tendency to categorize people in terms of their language decreases, can one say that a child is truly bilingual.