The current reliance on linguistic data for inferences about the concept–word relationship has led to serious questions being raised regarding the existence and facilitative role of prelinguistic categories in early word learning. In three experiments a multiple habituation paradigm was used to examine the ability of 7- and 9-month-old prelinguistic infants to form a natural, basic-level object category. In Experiment 1, 9-month-old infants appeared to form a category of bird, but only when habituated to prototypical exemplars as opposed to poor exemplars. Discriminability between prototypical habituation exemplars and test stimuli was demonstrated in Experiment 2. In Experiment 3, 7-month-olds did not form a category of bird when habituated to prototypes. These findings constitute independent evidence for the existence of a linguistically relevant nonlinguistic category prior to the onset of word comprehension. Moreover, formation of prelinguistic categories appears to be facilitated by exposure to prototypes. Such goodness-of-exemplar effects suggest a structural similarity between infants' prelinguistic categories and early semantic categories. Finally, nonlinguistic categorization of natural basic-level objects, as represented in line drawings, appears to emerge between 0;7 and 0;9.

This longitudinal study of how preverbal infants communicate with their mothers utilized the situation in which the infant was seated in a highchair at lunchtime. This situation predisposed infants to use communication as a means, since they were often unable to achieve their goals without assistance. It was found that infants' communicative attempts were often unsuccessful; the present study focussed on how infants and mothers worked to establish the infants' intents after communication failures. In the preverbal negotiation of failed messages infants direct communicative behaviours to their mothers which their mothers fail to comprehend immediately, NEGOTIATIONS occur when mothers help infants make their intents clear. Negotiation episodes have four components: the infant's initial signal, the mother's comprehension failure, infant repairs and episode outcome. Changes in these components provide much information about how infants' communicative skills evolve during the transition to a linguistically based communication system. Negotiation episodes are contrasted with episodes called IMMEDIATE SUCCESSES in which the mother readily comprehends the intent behind the infant's signal, and MISSED ATTEMPTS in which the mother fails to pick up on the infant's signal. Taken together these three types of communicative episode reveal a degree of persistence and creativity on the part of the preverbal infant that is surprising in the light of prior research. Such episodes further reveal that the course of preverbal communication is NOT smooth.

Considerable interest has been generated concerning linguistic and cognitive factors influencing the onset of early combinatorial speech. The present diary study provides evidence that, for some children, the transition between the single-word and two-word stages may be governed by phonological constraints. The presence of a phonological selection strategy and consonant harmony rule in one child's developing phonological system is described. Evidence is presented suggesting that this consonant harmony constraint operated across morpheme boundaries. This had the effect not only of delaying the onset of two-word utterances, but also of influencing the selection of words that could occur in word combinations. The implications of these findings for explaining individual variation in the transition from single-word to combinatorial speech are discussed.

The effects of five factors on the sensitivity of 36 women to infant cries were studied. The variables were listener experience (none, one month, four months), age of crying infant (one month, four months), type of cry (tired, angry, hungry), cry typicality (prototypical, moderately typical) and cry length (fixed, variable). A five-way analysis of variance was performed after scores were converted to the signal detection measure of sensitivity, d′. In addition to several main effects, significant age of infant × typicality × cry type, typicality × listener experience, and typicality × cry length interactions were found. The finding of an influence of cry length provided a possible explanation for the discrepancy in results in the infant cry literature, since the better discriminated single cries of variable length were typical of those cry signals used in studies reporting successful discrimination, and the poorly discriminated 15 sec fixed-length cry sequences were typical of those used in the studies failing to find discrimination of infant cries.

One child's lexical development was followed from 1; 1 to 1; 7 to look for possible causes of early word overextensions. Lexical acquisition was observed for comprehension and production through the use of a parental diary and systematic language sampling. In addition, 16 nonsense words were taught in 10 experimental sessions over a two-month period to control for phonological effects. The results isolated six distinct factors behind early word overextensions. It is concluded that overextensions should not constitute the primary data for the construction of theories of semantic acquisition.

Two young children were studied from the period when their expressive lexicons were approximately 30 words until they showed productive two-word positional patterns in their speech. Word combinations meeting the criteria for positional productive, positional associative and groping patterns were identified and the period during which the words appearing in these patterns were acquired was then determined. Words used in positional productive patterns had generally emerged in the children's speech before those used in associative or groping patterns. When several words that could play a particular semantic role (e.g. actor) were already well established in the child's lexicon, positional productive patterns that were somewhat broader in scope appeared as early as lexically based patterns.

Observational/correlational research has established that children in stage 5 object permanence development use words that refer to the visible movement of objects, while it is not until stage 6 that they use words referring to the invisible movement of objects (e.g. gone). It is not clear, however, whether the cognitive competence evidenced by performance in the object permanence task is a prerequisite for these linguistic productions or whether they both emerge simultaneously from some underlying representation. The current study used a lexical training paradigm to teach object words, visible movement words, and invisible movement words to children at stage 5 and stage 6 object permanence development. Stage 6 children learned all three types of words equally well. Stage 5 children learned object and visible movement words, especially in comprehension, but did not learn the invisible movement word. These results indicate that the cognitive structures underlying performance in the object permanence task are genuine prerequisites for learning these types of words.

Mothers talked to their infants via a video system designed so that each partner saw a full-face, life-size image of the other on a screen before them, perfect eye-to-eye contact being possible. They were presented either with live, real-time video sequences of their infants, where communication was therefore potentially mutually responsive, or else with the same sequence replayed some minutes later. The mother's babytalk differed consistently between live and replay sequences. Since the infants' acts were identical in form in the two conditions, the only difference being the infant's potential responsiveness to the mother, these results are evidence for the infant's active role in contributing to the nature of interactions with adults.

The ability of children aged 0;1 to 2;6 to initiate and maintain topics of conversation is explored using videotaped data of mother–child interaction collected at home. An analysis of both verbal and non-verbal behaviours suggests that initially children attract attention exclusively to themselves as topics of conversation. The emergence of manipulative skills from 0; 5 and the development of deictic gestures from around the end of the first year facilitate the initiation of topics concerned with items in the physical environment. Finally, with the development of language, reference to intangibles becomes possible. In maintaining topics, children are initially capable of extended sequences only within the context of routines, but by 2;6 are able to maintain coherent topics independently. The implications of the analysis presented for understanding the role of prelinguistic communication in language development are discussed against the background of a modular framework.

Research is reported which investigated the ability of 4-month-old hearing infants to discriminate between gestures, derived from American Sign Language (ASL), that differ solely in terms of contrasts along underlying movement dimensions. Using an habituation–dishabituation task, it is shown that young infants can make such discriminations for global movement contrasts as well as contrasts along a single movement dimension. Thus, at four months, infants possess certain prerequisite perceptual abilities for the analysis of the signs of a visually specified language. Partial failure to dishabituate to another movement contrast, however, suggests that readiness to utilize the information in gestural events may vary depending on the movement in question. Results are contrasted to infant speech perception findings and implications for further research in the development of sign perception are discussed.

Mother–child (two-year-old) object labelling was studied in three natural discourse settings: (1) routine, caretaking; (2) free play; and (3) novel. Object labelling was found to be considerably more varied in these natural discourse settings than in experimental situations. While basic level tokens predominated in the free play context, they were significantly less prevalent in the routine and novel contexts. Additionally, subordinate level term usage was more common in the routine and novel contexts. The relation between mother and child labelling was also investigated and results indicated that context may be more important in determining level of labels than maternal modelling. Analyses of the discourse uses of non-basic level terms revealed that mothers were organizing the social-interactive context in ways that may facilitate child category formation.

This study provides longitudinal observations of young children's behaviours while viewing television in their own homes, over a time when the children were actively involved in the process of language acquisition. Sixteen children were observed for a period ranging from 0; 6 to 0;8. At the beginning, their ages ranged from 0; 6.15 to 5.15; at the end, from 1; 2.15 to 3;0. The observations yielded documentation of an overwhelming and consistent occurrence of language-related behaviours among children and parents in the viewing situation. The categories of child and adult talk are reported, with description and examples of each category. The categories are compared with those reported for parent–child interactions outside the viewing experience, – in particular joint book-reading. A model of television as a talking picture book is proposed. It is argued that television has the potential to serve as a facilitator of children's language acquisition.

This study examined topic discourse skills in 30 pre-operational level children interacting with their mothers in a free play situation. For each interaction, topic initiations/shadings were analysed for here-and-now, fantasy, and displacement topics. All turns (initiations, shadings and maintenance) involving these topic categories were also coded for communicative intent. Results indicated that children initiated/shaded more fantasy topics than their mothers, who initiated/shaded more displacement topics. Topic maintenance was significantly greater for fantasy and here-and-now topics than for displacement. Mothers initiated/shaded and maintained topics primarily by requests for all three topic categories. Children used more informatives to initiate/shade these topics, and maintained fantasy and displacement topics primarily by responses to mothers' questions. The results suggested a complex picture of children's management of discourse as it relates to topic and mothers' continuing role in facilitating their children's discourse skills.

Young children's productions of novel words serving as names of objects and actions were compared. Although the object and action names were matched according to consonant and syllable structure, accurate production of newly emerging consonants was greater for the object words for each of the measures used: spontaneous production and unsolicited imitation during the word exposure sessions, and responses to production probes administered during and following the exposure sessions. These findings are attributed to the fact that action words have greater semantic complexity than object words, and that the increased processing requirements involved in referring to actions reduce the capacity to use newly developing sounds in these words.

Twenty-month-old children learned to recognize nonsense labels for five novel object concepts and were tested on generalization to variants of these concepts. Children were presented with either one or three examples of each object type during learning sessions. Results showed that receptive learning of names for object concepts was significantly related to a number of possible manipulations specific to each object type and to labelling by children. Children's generalization choices were consistent with adults' ranking of similarity of variants to concept prototypes. Children who learned less well were more likely to generalize to new instances of an object concept and to a greater number of variants if they had been exposed to three rather than one example during training sessions. Results also support the hypothesis that differentiation of objects in interaction is important to the formation of an object concept at this age.

This study assesses the role of frequency of input in the acquisition of the present perfect by Scottish and American children. Two questions were addressed: (1) Do adults speaking Scottish English use the present perfect more frequently in speech to children than those speaking American English? (2) If there is a difference in the frequency of input, how does this affect the course of development of this structure in the language of Scottish vs. American children? Cross-sectional data were collected from 12 Scottish and 12 American children aged 3; 0 to 6; 4 and from adults interacting with them in naturalistic settings. The data led to the conclusions that (1) Scottish adults use the present perfect construction in their speech to children much more frequently than American adults do; (2) Scottish children use the present perfect construction in their speech long before their American counterparts; and (3) frequency of input does play a major role in the timing and order of acquisition of the present perfect. However, its role appears to be an interactive one, in which it conspires with factors such as semantic, syntactic, and cognitive simplicity to make some forms easier to learn than others.

The conclusion that information regarding the grammatically of children's speech is unavailable in parental input has recently been challenged (Moerk 1983 a, b, Hirsh-Pasek, Treiman & Schneiderman 1984). The present study expanded on this research by broadening the definition of ‘negative feedback’ and by describing individual styles of mother–child dialogues. The purpose was to investigate whether mothers of four 2-year-old children responded differentially to their children's well-formed or ill-formed utterances with explicit and implicit feedback. The middle-class, English-speaking, mother–child dyads were recorded in a naturalistic context at home during play and eating activities. Explicit and implicit feedback were different in terms of the proportion of responses available to the child and their relation to well-formed and ill-formed utterances. The style of response was similar for most analyses across the four mothers.

With the expectation that an examination of language between toddler twins in their home environment would reveal characteristics unique to the subjects' twin status, 31 hours of crib-talk between identical twin girls and diary records of their speech were examined. It was found that the subjects developed conventional syntax and vocabulary, but adapted them in ways which appropriately expressed their twin status. Three salient examplesinclude their use of a double name for themselves as a team, their use of singular verbs in reference to themselves together, and their use of the singular pronoun me in pronominal reference to themselves as a team.

This paper reports on a cross-sectional acoustical investigation of the development of the voicing contrast in Thai word-initial stops. Voice onset time (VOT) productions associated with three bilabial stops (/b p ph/), three alveolar stops (/d t th/), and two velar stops (/k kh/) were measured in seven 3-year-old children, seven 5-year-old children, seven 7-year-old children, and seven adults. Within each age group, differences in mean VOT between homorganic stop consonants indicated that 3-year-olds have acquired all voicing contrasts except /b/ vs. /p/ and /d/ vs. /t/. By age five, children have acquired all voicing contrasts. However, as measured by differences in mean VOT across age groups, 5-year-olds still do not produce /b/ or/d/ in an adult-like manner. Issues concerning the order of acquisition and nature of development of stop consonants are discussed.