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…

Research on "parentese," the acoustically exaggerated, slower, and higher-pitched speech directed toward infants, has mostly focused on maternal contributions, although it has long been known that fathers also produce parentese. Given recent societal changes in family dynamics, it is necessary to revise these mother-centered models of…

Why do infants learn some words earlier than others? Many theories of early word learning focus on explaining how infants map labels onto concrete objects. However, words that are more abstract than object nouns, such as "uh-oh," "hi," "more," "up," and "all-gone," are typically among the first to…

Children's daily contexts shape their experiences. In this study, we assessed whether variations in infant placement (e.g., held, bouncy seat) are associated with infants' exposure to adult speech. Using repeated survey sampling of mothers and continuous audio recordings, we tested whether the use of independence-supporting placements was…

Children learn what words mean from hearing words used across a variety of contexts. Understanding how different contextual distributions relate to the words young children say is critical because context robustly affects basic learning and memory processes. This study examined children's everyday experiences using naturalistic video recordings to…

This research brings new evidence on early lexical acquisition in Wichi, an under-studied indigenous language in which verbs occupy a privileged position in the input and in conjunction with nouns are characterized by a complex and rich morphology. Focusing on infants ranging from one- to three-year-olds, we analyzed the parental report of…

This study examines the quantity and quality of child-directed speech across household activities in a socioeconomically diverse sample of Argentinian Spanish-speaking children, an understudied population. Thirty children (mean: 14.3 months) and their families were audio-recorded for four hours. The middle two hours were transcribed and analysed…

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…

Fourteen-month-old infants are unable to link minimal pair nonsense words with novel objects (Stager & Werker, 1997). Might an adult's productions in a word learning context support minimal pair word-object association in these infants? We recorded a mother interacting with her 24-month-old son, and with her 5-month-old son, producing nonsense…

Researchers disagree as to the importance for infant language learning of isolated words, which occur relatively rarely in input speech. Brent and Siskind (2001) showed that the first words infants "produce" are words their mothers used most frequently in isolation. Here we investigate the long-term effects of presentation mode on…

Parent language input is a well-established predictor of child language development. Multisensory attention skills (MASks; intersensory matching, shifting and sustaining attention to audiovisual speech) are also known to be foundations for language development. However, due to a lack of appropriate measures, individual differences in these skills…

Across languages, lexical items specific to infant-directed speech (i.e., 'baby-talk words') are characterized by a preponderance of onomatopoeia (or highly iconic words), diminutives, and reduplication. These lexical characteristics may help infants discover the referential nature of words, identify word referents, and segment fluent speech into…

High rates of error and variability in early word production may signal speech sound disorder. However, there is little consensus regarding the degree of error and variability that may be expected in the typical range. Relatedly, while variables including child age, word frequency and word phonological neighbourhood density are associated with…

Early trilingual development is an excellent testing ground for input reduction effects on acquisition outcomes. This article reports a study investigating input-outcome relations in a child Leo in Hong Kong, who was addressed to in Mandarin, Cantonese and later also in English by caretakers through 'one caretaker-one language' and 'one day-one…

This study investigates the pitch properties of infant-directed speech (IDS) specific to word-learning contexts in which mothers introduce unfamiliar words to children. Using a semi-spontaneous story-book telling task, we examined (1) whether mothers made distinctions between unfamiliar and familiar words with pitch in IDS compared to…