Emotion and language are very common in young children's everyday lives. Hour by hour, they play, listen, vocalize, react, and emote. Despite the centrality of emotion and language to toddlers' local environments, the dynamic interplay of these communicative signals is practically unexplored. Here, we investigated how fluctuations in caregiver and…

Early vocabulary development benefits from diverse lexical exposures within children's language environment. However, the influence of lexical diversity on children as they enter middle childhood and are exposed to multimodal language inputs remains unclear. This study evaluates global and local aspects of lexical diversity in three…

The last decade has seen an exponential rise in children's digital media use, as well as growing evidence that it is associated with changes in children's vocabulary. However, while high rates of low-quality digital media have been associated with lower "amounts" of words a child says, little work has examined whether digital media…

Questions about early word knowledge pervade the literature on both typical and atypical language trajectories. To determine which words an infant knows, researchers have relied on two types of measures--caregiver-report and eye-gaze behavior. When these measures are compared, however, their results frequently fail to converge, making it difficult…

Parental language input is a key predictor of child language achievement. Parentese is a widely used style of child-directed speech (CDS) distinguished by a higher pitch and larger pitch range. A recent parent coaching randomized control trial (Parentese-RCT) demonstrated that English-speaking US parents who were coached to use parentese with…

The speech register that adults especially caregivers use when interacting with infants and toddlers, that is, infant-directed speech (IDS) or baby talk, has been reported to facilitate language development throughout the early years. However, the neural mechanisms as well as why IDS results in such a developmental faciliatory effect remain to be…

This study investigates how neural networks address the properties of children's linguistic knowledge, with a focus on the "Agent-First" strategy in comprehension of an active transitive construction in Korean. We develop various neural-network models and measure their classification performance on the test stimuli used in a behavioural…

Previous research shows that infants of parents who are more likely to engage in socially contingent interactions with them tend to have larger vocabularies. An open question is "how" social contingency facilitates vocabulary growth. One possibility is that parents who speak in response to their infants more often produce larger…

Children learn language by listening to speech from caregivers around them. However, the type and quantity of speech input that children are exposed to change throughout early childhood in ways that are poorly understood due to the small samples (few participants, limited hours of observation) typically available in developmental psychology. Here…

Do mono- and bilingual children differ in the way they learn novel words in ambiguous settings? Listeners may resolve referential ambiguity by assuming that novel words refer to unknown, rather than known, objects--a response known as the "mutual exclusivity effect." Past research suggested that mono- and bilinguals differ with regard to…

A critical aspect of spoken language development is learning to categorize the sounds of the child's language(s). This process was thought to develop early during infancy to set the stage for the later development of higher-level aspects of language (e.g., vocabulary, syntax). However, many recent studies have shown that speech categorization…

Word learning studies traditionally examine the narrow link between words and objects, indifferent to the rich contextual information surrounding objects. This research examined whether children attend to this contextual information and construct an associative matrix of the words, objects, people, and environmental context during word learning.…

A growing body of work suggests that speaker-race influences how infants and toddlers interpret the meanings of words. In two experiments, we explored the role of speaker-race on whether newly learned word-object pairs are generalized to new speakers. Seventy-two 20-month-olds were taught two word-object pairs from a familiar race speaker, and two…

What is vision's role in driving early word production? To answer this, we assessed parent-report vocabulary questionnaires administered to congenitally blind children (N = 40, Mean age = 24 months [R: 7-57 months]) and compared the size and contents of their productive vocabulary to those of a large normative sample of sighted children (N =…

Children achieve better long-term language outcomes than adults. However, it remains unclear whether children actually learn language "more quickly" than adults during real-time exposure to input--indicative of true superior language learning abilities--or whether this advantage stems from other factors. To examine this issue, we…