Previous research has shown that children go through a stage in which they know that the number words each refer to a distinct numerosity, yet do not know WHICH numerosity each number word picks out (Wynn, 1992). How do children attain this level of knowledge? We explore the possibility that particular properties of how number words are used within sentences inform children of the semantic class to which they belong. An analysis of transcripts of the spontaneous speech of three one- and two-year-old children and their parents (from the CHILDES database; MacWhinney & Snow, 1990) suggests that the relevant cues are available as input in parents' speech to children, and that children generally honour these properties of number words in their own speech. Implications of this proposal for word learning more generally are discussed.

This paper examines naturalistic samples of adult-to-child speech to determine if variations in the input are consistent with reported variations in the proportions of nouns and verbs in children's early vocabularies. It contrasts two PRO-DROP languages, Italian and Mandarin, with English. Naturalistic speech samples from six 2;0 English-, six 1;11 Italian-, and ten 1;10 Mandarin-speaking children and their caregivers were examined. Adult-to-child speech was coded for the type frequency, token frequency, utterance position, and morphological variation of nouns and verbs as well as the types and placements of syntactic subjects and the pragmatic focus of adult questions. Children's spontaneous productions of nouns and verbs and their responses to adult questions were also examined. The results suggest a pattern consistent with the children's spontaneous production data. Namely, the speech of English-speaking caregivers emphasized nouns over verbs, whereas that of Mandarin-speaking caregivers emphasized verbs over nouns. The data from the Italian-speaking caregivers were more equivocal, though still noun-oriented, across these various input measures.

Although much research has investigated children's use of metaphoric language, methodological concerns raise questions about the conclusions, and it remains unclear whether preschoolers can produce metaphors. These studies employed a new methodology to test children's ability to produce metaphors incorporated into metaphoric compounds. In two studies, 59 children aged 2;8–4;3, 63 children aged 4;4–6;1, and 34 adults participated in elicited production tasks. In Study 1, subjects in the COMPOUND condition corrected a puppet's incorrect compound labels for pictures that had metaphoric resemblances to other objects (e.g. ‘leaf-bug’ for a bug shaped like a stick). Subjects in the NON-METAPHORIC condition heard incorrect compounds describing pictures without obvious metaphoric resemblance (e.g. ‘leaf-bug’ for a round black beetle). Children in the REVERSAL condition heard compounds with nouns reversed (e.g. ‘bug-leaf’ for the stick-bug) to discover whether children distinguished between the literal and metaphoric labels. Study 2 provided an additional test of children's metaphoric–literal distinction. Results showed that children as young as 3;0 produced intentional, appropriate metaphors incorporated into compound nouns when the stimuli and puppet's labels primed recognition of metaphoric similarity and compound production. Moreover, children showed evidence of a distinction between literal and metaphoric labels. The data show that preschool children have an early ability to use metaphoric language but that significant developmental change occurs between the ages of 3;0 and 5;0 as well as beyond 5;0. Additionally, metaphoric language in preschoolers is not limited to single-word renamings.

This study examines individual growth rates in definitional skill over a period of three to six years, for 68 low-income children. Children were asked to define words once a year at school, from kindergarten (youngest administration at 5;3) through fourth grade (oldest administration at 10;10). A plateau was observed between age nine and ten both for percent formal definitions (characterized by presence of a superordinate) and for the quality of formal definitions. The plateau was lower than the theoretical ceiling for these measures. However, the children appear to have attained ‘adult levels’ of definitional skill: forty-seven fourth-graders (aged 9;1 to 10;10) performed higher, on average, than their own mothers when giving definitions. These results support the notion that definitional skill is related to being part of an academic culture: low-income mothers, whose formal schooling is complete, generally do not give oral definitions to simple nouns as well as do their nine- to ten-year-old children.

This paper examines two issues concerning the acquisition of grammatical morphemes: (1) How is the acquisition of grammatical morphemes influenced by prosodic and phonological characteristics of the language being learned? and (2) What sorts of prosodic and phonological properties do grammatical morphemes have that might aid children in applying particular segmentation strategies? To address these issues, we compared the acquisition of grammatical morphemes in a pair of morphosyntactically similar but prosodically different languages, namely Taiwan Mandarin Chinese (TMC) and Taiwanese (TW). We analyse the patterns of realization and omission of a highly frequent subset of grammatical morphemes in six children's speech, recorded between the ages 1;6 and 2;3. The results from the between-language comparisons suggest that rhythmic characteristics of languages can affect segmentation by providing different kinds of prosodic handles for children to grasp at.

This paper considers cross-linguistic findings concerning the early development of formal, arbitrary, grammatical systems in normal hearing and deaf children and in children with congenital brain abnormalities. The paper reviews evidence showing an early acquisition of grammatical forms. Such learning is typically dissociated from the development of the relevant semantics. Form–function correspondences were not required for the development of morphological paradigms and for certain aspects of formal syntax. This finding held across all the populations studied.

It is hypothesized that the autonomous nature of these formal paradigms accounts for their priority in learning cross-linguistically.

This study examines mealtimes of preschoolers' families to determine whether rare words are used in informative ways so that a child could learn their meanings. Is there an association between informative use of rare words and the child's later vocabulary? Each use of rare words in 160 transcripts was coded for whether it was informative or uninformative. Each informative exchange was coded for type of strategy used to provide support: physical or social context, prior knowledge, and semantic support. There were 1,631 exchanges around rare words. About two-thirds of these exchanges were informative uses from which the child could learn the word's meaning. The most frequent strategy used was semantic support, accounting for two-thirds of strategies used. The frequency of use of rare words was positively correlated with age-five and age-seven PPVT scores.

This study investigated whether and when children establish various semantic relations between old and new words. Fifty two-year-olds were taught labels for objects previously referred to by an overextended term. We found that children were more likely to learn a new label when (a) it referred to a new object that was perceptually dissimilar, rather than similar, to a known one, and (b) when linguistic information indicated it had an inclusion, rather than a mutually exclusive, relation to a known label. Children were more likely to interpret a new label as mutually exclusive to a known one when their referents were perceptually dissimilar. These findings are discussed in light of theories of lexical development, particularly with regard to conceptualizations of constraints on the acquisition of word meaning.

Reports that infants imitate the vocal pitch characteristics of adult caregivers (e.g. Lewis, 1936/1951) include Lieberman's (1967; Lieberman, Ryalls & Rabson, 1982) claim that infants differentially adjust their vocal pitch or fundamental frequency (f0) towards that of their caregivers, resulting in higher mean pitch when interacting with mothers than when interacting with fathers. However, a recent cross-sectional study of infants at ages 0;8 to 0;9 and 1;0 failed to find evidence of differential pitch adjustment toward male and female caregivers (Siegel, Cooper, Morgan & Brennesie-Sarshad, 1990). A more sensitive test of Lieberman's claims would be to use a longitudinal design, with spontaneous recording sessions repeated over many months. The current study presents data from a longitudinal case study of an infant recorded at ages 0;3, 0;7, 0;10, 1;3 and 1;5 interacting with each of her parents in spontaneous play sessions and in isolated play. The infant in our study did not demonstrate significant adjustment of her vocal pitch in the direction of either parent. However, we did find evidence for consistent adjustment by the parents, in accord with the literature on infant-directed speech and mother–infant dyadic interactions, which suggest that the parents adjusted their behaviour to suit the infant more than vice versa.

Williams syndrome (WS), a rare neurodevelopmental disorder, is of special interest to developmental psycholinguists because of its uneven linguistico-cognitive profile of abilities and deficits. One proficiency manifest in WS adolescents and adults is an unusually large vocabulary despite serious deficits in other domains. In this paper, rather than focus on vocabulary size, we explore the processes underlying vocabulary acquisition, i.e. how new words are learned. A WS group was compared to groups of normal MA-matched controls in the range 3–9 years in four different experiments testing for constraints on word learning. We show that in construing the meaning of new words, normal children at all ages display fast mapping and abide by the constraints tested: mutual exclusivity, whole object and taxonomic. By contrast, while the WS group showed fast mapping and the mutual exclusivity constraint, they did not abide by the whole object or taxonomic constraints. This suggests that measuring only the size of WS vocabulary can distort conclusions about the normalcy of WS language. Our study shows that despite equivalent behaviour (i.e. vocabulary test age), the processes underlying how vocabulary is acquired in WS follow a somewhat different path from that of normal children and that the atypically developing brain is not necessarily a window on normal development.

In a recent note, Marcus (1995) suggests that the rate of overregularization of English irregular plural nouns is not substantively different from that of English irregular past tense verbs. This finding is claimed to be in conflict with the predictions of connectionist models (Plunkett & Marchman, 1991, 1993) which are said to depend solely on the dominance of regular over irregular forms in determining overregulation errors. However, these conclusions may be premature given that Marcus averaged overregulation rates across irregular nominal forms that varied in token frequency and across samples representing a broad range of children's ages. A connectionist view would predict an interplay between type frequency and other item level factors, e.g. token frequency, as well as differences in the developmental trajectories of the acquisition of nouns and verbs. In this response, we briefly review longitudinal parental report data (N=26) which indicate that children are significantly more likely to produce noun overregularizations than verb overregularizations across a prescribed age period (1;5 to 2;6). At the same time, these data also show that children are familiar with proportionately more irregular nouns than irregular verbs. These findings are consistent with the predictions of Plunkett & Marchman (1991, 1993) in that the larger regular class affects the frequency of noun errors but also that familiarity with individual irregular nouns tends to reduce the likelihood of overregularizations. In contrast to the conclusion of Marcus (1995), the connectionist approach to English inflectional morphology provides a plausible explanation of the phenomenon of overregularization in both the English plural and past tense systems.