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…

Purpose: This study examines online speech processing in typically developing and late-talking 2-year-old children, comparing both groups' word recognition, word prediction, and word learning. Method: English-acquiring U.S. children, from the "When to Worry" study of language and social--emotional development, were identified as typical…

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…

Toddlers vary widely in the rate at which they develop vocabulary. This variation predicts later language development and school success at the group level; however, we cannot determine which children with slower vocabulary development in the second year will continue to have difficulty. In this article, I argue that this is because we lack…

Learning about emotions is an important part of children's social and communicative development. How does children's emotion-related vocabulary emerge over development? How may emotion-related information in caregiver input support learning of emotion labels and other emotion-related words? This investigation examined language production and input…

Children's ability to recognize object shape is foundational for successful early word learning. However, the prototypical shape of objects may not be easily accessible--take margarita glasses, for instance. The current study examined 304 U.S. children 17- to 42-month-old (152 females) from 2017 to 2020, asking how shape, age, and vocabulary…

Purpose: This feasibility study examined a caregiver-implemented telehealth model of the Vocabulary Acquisition and Usage for Late Talkers (VAULT) protocol. We asked whether caregivers could reach fidelity on VAULT, if the protocol was socially and ecologically valid, and if late-talking toddlers could learn new words with this model. Method: Five…

Vocabulary size is a crucial early indicator of language development, for both monolingual and bilingual children. Assessing vocabulary in bilingual children is complex because they learn words in two languages, and there remains significant controversy about how to best measure their vocabulary size, especially in relation to monolinguals. This…

The interplay between self-regulation related skills and language is well recognized in dynamic theories, but few empirical studies have tested it, especially in toddlers. The current study examines the bidirectional links between self-regulation related skills and expressive vocabulary in a longitudinal study during toddlerhood. Participants were…

Purpose: The current investigation evaluated the extent to which early noun, verb, and adjective lexicon sizes predicted later grammatical outcomes in Mandarin-speaking children with and without late language emergence (LLE) using a parent report. Method: In Study 1, the parents of 24 Mandarin-speaking children with typical language filled out the…

To efficiently learn new words, children use constraints such as mutual exclusivity (ME) to narrow the search for potential referents. The current study investigated the use of ME in toddlers with autism spectrum disorder (ASD) and neurotypical (NT) peers matched on nonverbal cognition. Thirty-two toddlers with ASD and 26 NT toddlers participated…

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'…

The prevalence of late language emergence (LLE) in young children is high, comprising 10 to 20% of toddlers. Late language emergence refers to children who do not use at least 50 single words and 2-word phrases at the age of two. Current best practices for the under-three population with or at risk of having disabilities include the use of…

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…

Children learn words in environments where there is considerable variability, both in terms of the number of possible referents for novel words, and the availability of cues to support word-referent mappings. How caregivers adapt their gestural cues to referential uncertainty has not yet been explored. We tested a computational model of…