The aim of the study presented here was to examine variations in the forms and functions of agreement and refusal messages – which can be solely gestural, solely verbal, or combined gestural and verbal – by thirty children aged 1;4, 2;0, and 3;0 (ten in each age group) observed at home during an interaction with their mother. The results showed that even though verbal forms were the predominant ones as a whole, gestural forms were carried over into the linguistic period, and for the youngest children, constituted the sole means of agreeing and refusing. They also showed that the most frequently expressed function was assertion.

Studies of comprehension of the quantifiers all and more are reported. The subjects were children between the ages of three and five. There were two main conditions. In one of these the objects to which the quantifiers related were enclosed in containers which either were or were not filled by the objects. In the other no containers were present. These conditions yielded substantially different response patterns. The relation of the findings to those typically obtained from Piagetian conservation tasks is discussed; and the implications for theories of semantic development are considered.

Children typically acquire their native language naturally and spontaneously at a very young age. The emergence of early grammar can be predicted from children's vocabulary size and composition (Bates et al., 1994; Bates, Bretherton & Snyder, 1998; Bates & Goodman, 1997). One central question in language research is understanding what causes the changes in early language acquisition. Some researchers argue that the qualitative and quantitative shifts in word learning simply reflect the changing character of the child's cognitive maturity (for example, Gentner, 1982), while others argue that the trajectory of early language acquisition is driven by the child's growing familiarity with the language (Gillette, Gleitman, Gleitman & Lederer, 1999; Snedeker & Gleitman, 2004). These hypotheses are difficult to adjudicate because language acquisition in virtually all hearing children begins from birth and occurs simultaneously with cognitive development and brain maturation. The acquisition of sign languages, in contrast, is frequently delayed until older ages. In the USA, over 90% of deaf children are born to hearing parents who do not use sign language (Schein, 1989). As a result, deaf children are often exposed to sign language as a first language at a range of ages well beyond infancy (Mayberry, 2007). In rare cases, some deaf individuals are isolated from all linguistic input until adolescence when they start receiving special services and begin to learn sign language through immersion (Morford, 2003). Case studies of language acquisition in such extreme late first-language (L1) learners provide a unique opportunity to investigate first-language learning. The current study investigates three cases of young teens who are in the early stages of acquiring American Sign Language (ASL) as a first language, to determine what first-language acquisition in adolescence looks like.

It is often assumed that children go through a stage in which they systematically overapply irregular past tense patterns to inappropriate verbs, as in wipe-wope, bring-brang, trick-truck, walk-has walken. Such errors have been interpreted both as reflecting over-use of minor grammatical rules (e.g. ‘change i to a’), and as reflecting the operation of a connectionist pattern associator network that superimposes and blends patterns of various degrees of generality. But the actual rate, time course, and nature of these errors have never been documented. We analysed 20,000 past tense and participle usages from nine children in the CHILDES database, looking for overapplications of irregular vowel-change patterns, as in brang, blends, as in branged, productive suffixations of -en, as in walken, gross distortions, as in mail-membled, and double-suffixation, as in walkeded. These errors were collectively quite rare; children made them in about two tenths of one per cent of the opportunities, and with few stable patterns: the errors were not predominantly word-substitutions, did not occur predominantly with irregular stems, showed no consistency across verbs or ages, and showed no clear age trend. Most (though not all) of the errors were based closely on existing irregular verbs; gross distortions never occurred. We suggest that both rule-theories and connectionist theories have tended to overestimate the predominance of such errors. Children master irregular forms quite accurately, presumably because irregular forms are just a special case of the arbitrary sound-meaning pairings that define words, and because children are good at learning words.

Previous research has used cross-linguistic priming methodology with bilingual adults to explore the nature of their syntactic representations. The present paper extends the use of this methodology to bilingual children to investigate the relation between the syntactic structures of their two languages. Specifically, we examined whether the use of passives by the experimenter in one language primed the subsequent use of passives by the child in the other language. Results showed evidence of syntactic priming from Spanish to English: hearing a Spanish sentence containing a passive led to the increase in children's production of the parallel structure in English. However, there was no priming in the other direction: hearing an English sentence containing a passive did not increase children's use of the parallel structure in Spanish. These results provide evidence for both the integration of syntactic representations in bilingual children and the asymmetry of the relation between their two languages.

The English orthography is morphophonemic: spellings encode both morphemes and phonemes. Questions of the starting point and extent of young children's understanding of the link between morphemes and spelling are important for theories of spelling development. We conducted two experiments to address these issues. In Experiment 1, 65 six- to eight-year-old English-speaking children spelled just the first sections of inflected, derived and control words. Their spelling of these first segments was better in inflected and derived words than in control words. The findings were replicated in Experiment 2 with 78 six- to eight-year-old children spelling a greater number of items. These two studies converge on the conclusion that, in specific testing situations, six- to eight-year-old children appreciate the role of root morphemes in the spelling of both inflected and derived words. These results are discussed in relation to current models of spelling development.

The influence of frequency of occurrence in input upon early lexical acquisition was examined within an experimental paradigm. Twelve children (1; 0·21 to 1; 3·15) were presented with 16 contrived lexical concepts, each involving a nonsense word and four referents, over ten experimental sessions. Within each concept two exemplars were presented frequently and two were presented infrequently. Overall the children named more frequently presented exemplars than infrequently presented exemplars. However, when the absolute number of presentations was held constant, distributed (infrequent) presentations led to greater acquisition than massed (frequent) presentations.

An experiment on children between 2; 0 and 7; 0 showed that they initially interpret the same X to mean ‘same kind’ in contexts where it actually means ‘same one’. This led to a critical evaluation of Piaget's implicit contention that young children are using determiners anaphorically. Stress is placed on the linguistic rather than conceptual component of children's behaviour in experiments involving questions of the type: Is it the same X? It is argued that language is not only the tool of intelligence for representing ongoing cognitive development, but that it is also a problem area for children within its own right. It is suggested that the importance of young children's processing procedures on the linguistic environment has hitherto been underestimated in Piaget's interactive epistemology.

This study investigated different accounts of children's acquisition of non-subject wh-questions. Questions using each of 4 wh-words (what, who, how and why), and 3 auxiliaries (BE, DO and CAN) in 3sg and 3pl form were elicited from 28 children aged 3;6–4;6. Rates of non-inversion error (Who she is hitting?) were found not to differ by wh-word, auxiliary or number alone, but by lexical auxiliary subtype and by wh-word+lexical auxiliary combination. This finding counts against simple rule-based accounts of question acquisition that include no role for the lexical subtype of the auxiliary, and suggests that children may initially acquire wh-word+lexical auxiliary combinations from the input. For DO questions, auxiliary-doubling errors (What does she does like?) were also observed, although previous research has found that such errors are virtually non-existent for positive questions. Possible reasons for this discrepancy are discussed.

The past and present state of the empiricism–nativism issue is analysed. Empiricist philosophical doctrine (‘no innate ideas’) distinguished idea from structure or mechanism. However, Chomsky's conception of innate linguistic universals erased this distinction. The elimination left would-be empiricists without a coherent and defensible position. I argue that the issue remains alive primarily because of tension between two scientific tasks that face students of development. One is to discover what is cognitively and linguistically primitive, a task that encourages nativism. However, nativism is ultimately unsatisfactory because it systematically neglects the other task, which is to account for development, including the emergence of postulated innate primitives. To account for such primitives, it is necessary to relate them to particular central nervous System structures in such a way as to explain how the structure has the particular cognitive effects that define the primitive. That is likely to be difficult, and I show how the study of learning – much neglected in recent years – can help by reducing the number and type of innate primitives whose origin must be explained in that way.

In the linguistics field, liaison in French is interpreted as an indicator of interactions between the various levels of language organization. The current study examines the same issue while adopting a developmental perspective. Five experiments involving children aged two to six years provide evidence for a developmental scenario which interrelates a number of different issues: the acquisition of phonological alternations, the segmentation of new words, the long-term stabilization of the word form in the lexicon and the formation of item-based constructions. According to this scenario, children favour the presence of initial CV syllables when segmenting stored chunks of speech of the type word1-liaison-word2 (les arbres ‘the trees’ is segmented as /le/+/zarbr/). They cope with the variation of the liaison in the input by memorizing multiple exemplars of the same word2 (/zarbr/, /narbr/). They learn the correct relations between the word1s and the word2 exemplars through exposure to the well-formed sequence (un+/narbr/, deux+/zarbr/). They generalize the relation between a word1 and a class of word2 exemplars beginning with a specific liaison consonant by integrating this information into an item-based schema (e.g. un+/nX/, deux+/zX/). This model is based on the idea that the segmentation of new words and the development of syntactic schemas are two aspects of the same process.

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.

The notion of competence as it applies to child language is critically assessed in the light of evidence collected from a number of linguistic performances which share the same word-order rule. These performances – production, comprehension, judgment and correction – parallel Moravcsik's (1969) formulation of Chomsky's criteria for tacit knowledge of a rule, i.e. competence. It was found that these criteria are not all satisfied until the child is four or five years old, as the performances appear at very different points in time. Alternative criteria for tacit knowledge are suggested, with specific models of each performance replacing a general model of competence for early child speech.

Ostensive definitions of words are ambiguous as to their referent. In a study of 40 mother–infant dyads engaged in looking at picture-books, it was found that 95% of ostensive definitions referred to the whole object depicted, rather than to its parts, attributes or actions. On the rare occasions when mothers named parts of objects, they avoided misunderstanding of the level of reference either by naming the part immediately after naming the whole, or by including a reference to the whole in the definition of the part. What's that? questions are not used to request labelling of the part.

TURNABOUTS, which both respond to and require a response from the other (either verbal or nonverbal), were produced more than twice as often by mothers as by their children at 2; 2 and 2; 6, in videotaped dialogues during semi-structured play. The 27 mothers showed stable individual differences in this aspect of their turn-taking, across situations and across time. Children tended to take a reciprocal role rather than an imitative one within the immediate situation: if a mother produced many mands, her child produced few. At 2; 10 the children were tested for language comprehension, puzzle-solving and conversational engagement with an investigator. Mothers' mands at the earlier ages appeared to have a negative effect upon these measures, even when social class differences were controlled; but causal interpretations were complicated by the fact that language production measures also predicted the 2; 10 cognitive measures.

Children's narratives consist of event clauses and contextualizing or ‘evaluative’ clauses. Bamberg & Damrad-Frye (1991) and Bamberg (1994) claimed that young children make limited use of evaluative clauses because they are less able to adopt a global perspective on the narrative. In an earlier study, Karmiloff-Smith (1985) demonstrated that the narratives of younger children have coherence only at a local level. However, Wellman & Bartsch (1988) showed that young children could produce evaluative-like causal explanations if given a specific prompt. The present study on 160 young children aged five, seven, nine and eleven years examined their production of evaluatives in narratives of a story presented as a video sequence with no spoken dialogue, to ensure that the children's production was not simply a re-working of verbal input. Results indicated that prompts greatly facilitated children's production of evaluatives and that they could adopt a global perspective on the story when formulating evaluatives.

These results indicate that limitations in the narratives of young children are more plausibly explained by contextual factors influencing language production and by constraints on working memory than by children's presumed lack of understanding of the structure of events or their inferences about the minds of the characters.

Derived nominals are abstract nouns derived from verbs and adjectives by nominalization. This study traces the route taken by Hebrew-speaking children in the acquisition of Hebrew derived nominals (HDNs) of two types: action nominals which conform in structure to the small set of obligatory verb patterns (binyanim) (e.g. ktiva ‘writing’) and deverbal nouns, which belong to separate nominal patterns (e.g. maga ‘touch’). One hundred native speakers of Hebrew (children aged 5, 8, 11 and 15, and adults) were tested on comprehension and production of HDNs. The test items were grouped by binyan patterns and by morphological regularity. Results showed that acquisition of HDNs starts at about age 8 and is not complete by age 15, and that task type, binyan pattern and morphological regularity all affect ease of acquisition. We consider the strategies employed in the course of acquisition of HDNs and offer an explanation for this late acquisition which requires a vast amount of prior integrated knowledge.

In this longitudinal investigation of the emerging grammar of seven children, differences in linguistic acquisition were observed. The syntactic analyses applied to the corpora included examination of emerging complexity, observance of word order constraints and subject-predicate specification among others. These analyses revealed two distinct styles of syntactic acquisition. These linguistic styles appeared to be sex- and speed-related with specific ties to particular utterance types and grammatical-relational specification. The observed styles of syntactic acquisition were differentiated by these differences so that the differences themselves constituted the style characteristics.

Two-year-olds learn language quickly but how they exploit adult input remains obscure. Twenty-nine children aged 2;6 to 3;2, divided into three treatment groups, participated in an intervention experiment consisting of four sessions 1 week apart. Pre- and post-intervention sessions were identical for all children: children heard a wh-question and attempted to repeat it; a ‘talking bear’ answered. That same format was used for the two intervention sessions for children in a quasicontrol condition (Group QC). Children receiving modelling (Group M) heard a question twice before repeating it; those receiving implicit correction (Group IC) heard a question, attempted to repeat it, and heard it again. All groups improved in supplying and inverting an auxiliary for target questions with trained auxiliaries. Only experimental children generalized to auxiliaries on which they had not been trained. Very little input, if concentrated but varied, and presented so that the child attends to it and attempts to parse it, is sufficient for the rapid extraction and generalization of syntactic regularities. Children can learn even more efficiently than has been thought.