When linguistic information alone does not clarify a speaker's intended meaning, skilled communicators can draw on a variety of cues to infer communicative intent. In this paper, we review research examining the developmental emergence of preschoolers’ sensitivity to a communicative partner's perspective. We focus particularly on preschoolers’ tendency to use cues both within the communicative context (i.e. a speaker's visual access to information) and within the speech signal itself (i.e. emotional prosody) to make on-line inferences about communicative intent. Our review demonstrates that preschoolers’ ability to use visual and emotional cues of perspective to guide language interpretation is not uniform across tasks, is sometimes related to theory of mind and executive function skills, and, at certain points of development, is only revealed by implicit measures of language processing.

Language exerts a powerful influence on our concepts. We review evidence documenting the developmental origins of a precocious link between language and object categories in very young infants. This collection of studies documents a cascading process in which early links between language and cognition provide the foundation for later, more precise ones. We propose that, early in life, language promotes categorization at least in part through its status as a social, communicative signal. But over the first year, infants home in on the referential power of language and, by their second year, begin teasing apart distinct kinds of names (e.g. nouns, adjectives) and their relation to distinct kinds of concepts (e.g. object categories, properties). To complement this proposal, we also relate this evidence to several alternative accounts of language's effect on categorization, appealing to similarity (‘labels-as-features’), familiarity (‘auditory overshadowing’), and communicative biases (‘natural pedagogy’).

Perceptual representations of objects and approximate magnitudes are often invoked as building blocks that children combine to acquire the positive integers. Systems of numerical perception are either assumed to contain the logical foundations of arithmetic innately, or to supply the basis for their induction. I propose an alternative to this framework, and argue that the integers are not learned from perceptual systems, but arise to explain perception. Using cross-linguistic and developmental data, I show that small (~1–4) and large (~5+) numbers arise both historically and in individual children via distinct mechanisms, constituting independent learning problems, neither of which begins with perceptual building blocks. Children first learn small numbers using the same logic that supports other linguistic number marking (e.g. singular/plural). Years later, they infer the logic of counting from the relations between large number words and their roles in blind counting procedures, only incidentally associating number words with approximate magnitudes.

In order to understand how language abilities emerge in typically and atypically developing infants and toddlers, it is important to embrace complexity in development. In this paper, we describe evidence that early language development is an experience-dependent process, shaped by diverse, interconnected, interdependent developmental mechanisms, processes, and abilities (e.g. statistical learning, sampling, functional specialization, visual attention, social interaction, motor ability). We also present evidence from our studies on neurodevelopmental disorders (e.g. Down syndrome, fragile X syndrome, Williams syndrome) that variations in these factors significantly contribute to language delay. Finally, we discuss how embracing complexity, which involves integrating data from different domains and levels of description across developmental time, may lead to a better understanding of language development and, critically, lead to more effective interventions for cases when language develops atypically.

This study compares the use of the variable (q), which is realized as rural [q] and urban [ʔ], in the speech of twenty-two parents and their twenty-one children from the village of Oyoun Al-Wadi in Syria. The study shows that children acquire the general gendered linguistic pattern of the community but do not replicate the linguistic frequencies that exist in their immediate environment. Boys and girls exhibit different linguistic behavior. Boys deviate from the non-local caregivers' proportions and approach men's local linguistic behavior, although their local variant proportions remain lower; girls, even those with local mothers, approach the women's supralocal variant proportions. The study shows that sociolinguistic variation is not acquired from adults from a very early age; it is acquired later in life after accepting and ascertaining the gendered linguistic differences and appropriateness norms.

While recent studies suggest children can use cross-situational information to learn words, these studies involved minimal referential ambiguity, and the cross-situational evidence overwhelmingly favored a single referent for each word. Here we asked whether 2·5-year-olds could identify a noun's referent when the scene and cross-situational evidence were more ambiguous. Children saw four trials in which a novel word occurred with four novel objects; only one object consistently co-occurred with the word across trials. The frequency of distracter objects varied across conditions. When all distracter referents occurred only once (no-competition), children successfully identified the noun's referent. When a high-probability competitor referent occurred on three trials, children identified the target referent if the competitor was absent on the third trial (short-competition) but not if it was present until the fourth trial (long-competition). This suggests that although 2·5-year-olds’ cross-situational learning scales up to more ambiguous scenes, it is disrupted by high-probability competitor referents.

The MacArthur-Bates Communicative Development Inventories (CDIs) are a widely used family of parent-report instruments for easy and inexpensive data-gathering about early language acquisition. CDI data have been used to explore a variety of theoretically important topics, but, with few exceptions, researchers have had to rely on data collected in their own lab. In this paper, we remedy this issue by presenting Wordbank, a structured database of CDI data combined with a browsable web interface. Wordbank archives CDI data across languages and labs, providing a resource for researchers interested in early language, as well as a platform for novel analyses. The site allows interactive exploration of patterns of vocabulary growth at the level of both individual children and particular words. We also introduce wordbankr, a software package for connecting to the database directly. Together, these tools extend the abilities of students and researchers to explore quantitative trends in vocabulary development.

Children have to figure out the lexicalization of meaning components in learning verb semantics (e.g. Behrens, 1998; Gentner, 1982; Tomasello & Brooks, 1998). The meaning of an English state-change verb (e.g. break) is divided into two portions (i.e. cause and result), respectively encoded with a separate verb in a Mandarin resultative verb compound (RVC). The majority of Mandarin monomorphemic verbs do not specify any realization of a state change (like hunt), or only imply it (like wash) (Talmy, 2000). This study examines the acquisition of the constructional meaning of RVCs and the semantic division of labor between the component verbs. Four groups of Mandarin-learning children (aged 2;6, 3;6, 4;6, and 6;1) participated in an elicitation experiment. The results reveal that, although transparency in form facilitates their learning of the state-change meanings of RVCs, Mandarin children have difficulties in unpacking the meanings of individual verbs, revealing language-specific learning issues.

To better understand how toddlers integrate multiple learning strategies to acquire verbs, we compared sensorimotor recruitment and comparison learning because both strategies are thought to boost children's access to scene-level information. For sensorimotor recruitment, we tested having toddlers use dolls as agents and compared this strategy with having toddlers observe another person enact verbs with dolls. For comparison learning, we compared providing pairs of: (a) training scenes in which animate objects with similar body-shapes maintained agent/patient roles with (b) scenes in which objects with dissimilar body-shapes switched agent/patient roles. Only comparison learning boosted verb comprehension.

One strategy that children might use to sort words into grammatical categories such as noun and verb is distributional bootstrapping, in which local co-occurrence information is used to distinguish between categories. Words that can be used in more than one grammatical category could be problematic for this approach. Using naturalistic corpus data, this study asks whether noun and verb uses of ambiguous words might differ prosodically as a function of their grammatical category in child-directed speech. The results show that noun and verb uses of ambiguous words in sentence-medial positions do differ from one another in terms of duration, vowel duration, pitch change, and vowel quality measures. However, sentence-final tokens are not different as a function of the category in which they were used. The availability of prosodic cues to category in natural child-directed speech could allow learners using a distributional bootstrapping approach to avoid conflating grammatical categories.

This paper investigates English-speaking children's acquisition of raising constructions (e.g. John seems to Mary to be happy) and finds an asymmetric effect of NP type on their comprehension: an improvement in performance is observed when a lexical NP is raised across a pronominal experiencer (e.g. John seems to her to be happy) compared to when a pronoun is raised across a lexical NP experiencer (e.g. He seems to Mary to be happy). These results are consistent with a processing-based approach to intervention effects, which reduces children's difficulty with raising to a performance limitation, rather than a grammatical deficit.