Verb-marking errors such as "she play football" and "daddy singing" are a hallmark feature of English-speaking children's speech. We investigated the proposal that these errors are input-driven errors of commission arising from the high relative frequency of subject + unmarked verb sequences in well-formed child-directed…

We examined how noun frequency and the typicality of surrounding linguistic context contribute to children's real-time comprehension. Monolingual English-learning toddlers viewed pairs of pictures while hearing sentences with typical or atypical sentence frames ("Look at the…" vs. "Examine the…"), followed by nouns that were…

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…

Sometime before their second birthday, many children have a period of rapid expressive vocabulary growth called the vocabulary spurt. Theories of the underlying mechanisms differ: Accumulator models emphasize the accumulation of experience with words over time to yield a spurtlike pattern, while cognitive models attribute the spurt to cognitive…

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…

Recent research has demonstrated that individual differences in infant attention to faces and voices of women speaking predict language outcomes in childhood. These findings have been generated using two new audiovisual attention assessments appropriate for infants and young children, the Multisensory Attention Assessment Protocol (MAAP) and the…

Hearing words in sentences facilitates word recognition in monolingual children. Many children grow up receiving input in multiple languages -- including exposure to sentences that 'mix' the languages. We explored Spanish-English bilingual toddlers' (n = 24) ability to identify familiar words in three conditions: (i) single word…

Currently, no culturally and linguistically adapted autism screening tools are available in South Africa. The aim was to determine the reliability and concurrent validity of the adapted English and Northern Sotho-translated Modified Checklist for Autism in Toddlers--Revised with Follow-up (M-CHAT-R/F). Reliability was confirmed with near-perfect…

Purpose: Measuring the growth of young children's vocabulary is important for researchers seeking to understand language learning as well as for clinicians aiming to identify early deficits. The MacArthur-Bates Communicative Development Inventories (CDIs) are parent report instruments that offer a reliable and valid method for measuring early…

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…