Many children grow up hearing multiple languages, learning words in each. How does the number of languages being learned affect multilinguals' vocabulary development? In a pre-registered study, we compared productive vocabularies of bilingual (n = 170) and trilingual (n = 20) toddlers aged 17-33 months growing up in a bilingual community where…

Words that describe sensory perception give insight into how language mediates human experience, and the acquisition of these words is one way to examine how we learn to categorize and communicate sensation. We examine the differential predictions of the typological prevalence hypothesis and embodiment hypothesis regarding the acquisition of…

Previous studies have found correlations between parent input and child language outcomes, providing prima facie evidence for a causal relation. However, this could also reflect the effects of shared genes. The present study removed this genetic confound by measuring English vocabulary growth in 29 preschool-aged children (21 girls) aged…

The current study examined early grammatical marking in a relatively understudied language, Mandarin, by using the Mandarin version of MacArthur-Bates Communicative Development Inventory. Two waves of data collection included 338 monolingual children (17-36 months; 143 female) at Time 1 and 308 children (32-55 months; 139 female) at Time 2 and…

Purpose: Late talkers (LTs) are a group of children who exhibit delays in language development without a known cause. Although a hallmark of LTs is a reduced expressive vocabulary, little is known about LTs' processing of semantic relations among words in their emerging vocabularies. This study uses an eye-tracking task to compare 2-year-old LTs'…

There is consensus that the adult lexicon exhibits lexical competition. In particular, substantial evidence demonstrates that words with more phonologically similar neighbors are recognized less efficiently than words with fewer neighbors. How and when these effects emerge in the child's lexicon is less clear. In the current paper, we build on…

To examine whether children's acquisition of perspective-marking language supports development in their ability to reason about mental states, we conducted a longitudinal study testing whether proficiency with complement clauses around age 3 explained variance in false-belief reasoning 6 months later. Forty-five English-speaking 2- and 3-year-olds…

Background: As delays or disorders in early language and communication are the most prevalent symptom in children with disabilities, early screening is crucial to promote prevention, early diagnosis, and intervention. However, to the best of our knowledge, no screening tool is available for the joint assessment of early language and social…

We examined the size, content, and use of evaluative lexis by 26 English monolingual and 20 Spanish-English bilingual 30-month-old children in interaction with their mothers. We extracted the evaluative words, defined as words referring to cognition, volition, or emotion. Controlling for overall vocabulary skills as measured by the MacArthur-Bates…

Infants and toddlers experience the world in interaction with others. Likewise, social interactions are important in learning about math--concepts of number ("one," "two," "three"), space ("on top," "upside-down," "round"), and magnitude ("more," "big,"…

In children acquiring various languages, the early mastery of determiners strongly predicts syntactic development. What makes determiners important is not yet clear as there is a linguistic controversy regarding their syntactic behaviour. Some consider determiners to be similar to adjectives and to modify common nouns, while others consider the…

In bilingual language environments, infants and toddlers listen to two separate languages during the same key years that monolingual children listen to just one and bilinguals rarely learn each of their two languages at the same rate. Learning to understand language requires them to cope with challenges not found in monolingual input, notably the…

This paper examines the acquisition of demonstratives (e.g., "that," "there") from a cross-linguistic perspective. Although demonstratives are often said to play a crucial role in L1 acquisition, there is little systematic research on this topic. Using extensive corpus data of spontaneous child speech, the paper investigates…

In order for children to understand and reason about the world in an adult-like fashion, they need to learn that conceptual categories are organized in a hierarchical fashion (e.g., a dog is also an animal). While children learn from their first-hand observation of the world, social knowledge transmission via language can also play an important…

Purpose: This study was specifically designed to examine how verb variability and verb overlap in a morphosyntactic priming task affect typically developing children's use and generalization of auxiliary IS. Method: Forty typically developing 2- to 3-year-old native English-speaking children with inconsistent auxiliary IS production were primed…