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.

The phonetic characteristics of canonical babbling produced by Korean- and English-learning infants were compared with consonant and vowel frequencies observed in infant-directed speech produced by Korean- and English-speaking mothers. For infant output, babbling samples from six Korean-learning infants were compared with an existing English babbling database (Davis & MacNeilage, 1995). For ambient language comparisons, consonants and vowels in ten Korean and ten English infant-directed speech (IDS) samples were analyzed. The two infant groups demonstrated similar consonant patterns, but showed different vowel patterns from one another. For both languages, infant vowel patterns were related to those of ambient language IDS. Ambient language patterns were manifested in infant vowel output, perhaps because vowels are more perceptually and motorically available in the input and output capacities of babbling infants.

In this work, we examine a context in which a conflict arises between two roles that infant-directed speech (IDS) plays: making language structure salient and modeling the adult form of a language. Vowel devoicing in fluent adult Japanese creates violations of the canonical Japanese consonant–vowel word structure pattern by systematically devoicing particular vowels, yielding surface consonant clusters. We measured vowel devoicing rates in a corpus of infant- and adult-directed Japanese speech, for both read and spontaneous speech, and found that the mothers in our study preserve the fluent adult form of the language and mask underlying phonological structure by devoicing vowels in infant-directed speech at virtually the same rates as those for adult-directed speech. The results highlight the complex interrelationships among the modifications to adult speech that comprise infant-directed speech, and that form the input from which infants begin to build the eventual mature form of their native language.

The early development of vocalic and consonantal production in Mandarin-learning infants was studied at the transition from babbling to producing first words. Spontaneous vocalizations were recorded for 24 infants grouped by age: G1 (0 ; 7 to 1 ; 0) and G2 (1 ; 1 to 1 ; 6). Additionally, the infant-directed speech of 24 caregivers was recorded during natural infant–adult interactions to infer language-specific effects. Data were phonetically transcribed according to broad categories of vowels and consonants. Vocalic development, in comparison with reports for children of other linguistic environments, exhibited two universal patterns: the prominence of [ɛ] and [ə], and the predominance of low and mid vowels over high vowels. Language-specific patterns were also found, e.g. the early appearance and acquisition of low vowels [ɑ]. Vowel production was similar in G1 and G2, and a continuum of developmental changes brought infants' vocalization closer to the adult model. Consonantal development showed two universal patterns: labials and alveolars occurred more frequently than velars; and nasals developed earlier than fricatives, affricates and liquids. We also found two language-specific patterns: alveolars were more prominent than labials and affricates developed early. Universal and language-specific characteristics in G1 continued to be prominent in G2. These data indicate that infants are sensitive to the ambient language at an early age, and this sensitivity influences the nature of their vocalizations.

The present study investigates children's bias when interpreting novel noun–noun compounds (e.g. kig donka) that refer to combinations of novel objects (kig and donka). More specifically, it investigates children's understanding of modifier–head relations of the compounds and their preference for HAS or LOCATED relations (e.g. a donka that HAS a kig or a donka that is LOCATED near a kig) rather than a FOR relation (e.g. a donka that is used FOR kigs). In a forced-choice paradigm, two- and three-year-olds preferred interpretations with HAS/LOCATED relations, while five-year-olds and adults showed no preference for either interpretation. We discuss possible explanations for this preference and its relation to another word learning bias that is based on perceptual features of the referent objects, i.e. the shape bias. We argue that children initially focus on a perceptual stability rather than a pure conceptual stability when interpreting the meaning of nouns.

The aim of this study was to determine whether children with specific language impairment (SLI) are sensitive to completion cues in their comprehension of tense. In two experiments, children with SLI (ages 4 ; 1 to 6 ; 4) and typically developing (TD) children (ages 3 ; 5 to 6 ; 5) participated in a sentence-to-scene matching task adapted from Wagner (2001). Sentences were in either present or past progressive and used telic predicates. Actions were performed twice in succession; the action was either completed or not completed in the first instance. In both experiments, the children with SLI were less accurate than the TD children, showing more difficulty with past than present progressive, regardless of completion cues. The TD children were less accurate with past than present progressive requests only when the past actions were incomplete. These findings suggest that children with SLI may be relatively insensitive to cues pertaining to event completion in past tense contexts.

Parent report has proven a valid and cost-effective means of evaluating early child language. Norming datasets for these instruments, which provide the basis for standardized comparisons of individual children to a population, can also be used to derive norms for the acquisition of individual words in production and comprehension and also early gestures and symbolic actions. These lexical norms have a wide range of uses in basic research, assessment and intervention. In addition, cross-linguistic comparisons of lexical development are greatly facilitated by the availability of norms from diverse languages. This report describes the development of CLEX, a new web-based cross-linguistic database for lexical data from adaptations of the MacArthur-Bates Communicative Development Inventories. CLEX provides tools for a range of analyses within and across languages. It is designed to incorporate additional language datasets easily, and to permit users to define mappings between lexical items in pairs of languages for more specific cross-linguistic comparisons.

Adults distinguish between ironic remarks directed at targets (sarcasm) and ironic remarks not directed at specific targets. We investigated the development of children's appreciation for this distinction by presenting these speech acts to 71 five- to six-year-olds and 71 nine- to ten-year-olds. Five- to six-year-olds were beginning to understand the non-literal meanings of sarcastic speakers and ironic speakers but did not distinguish ironic and sarcastic speakers' intentions. Nine- to ten-year-olds were more accurate at understanding sarcastic and ironic speakers and they distinguished these speakers' intentions, rating sarcastic criticisms as more ‘mean’ than ironic criticisms. These results show that children can determine the non-literal meanings of sarcasm and irony by six years of age but do not distinguish the pragmatic purposes of these speech acts until later in middle childhood.