Infants begin to produce abstract "math" words -- such as numbers (e.g., "two"), spatial terms (e.g., "down"), and magnitude words (e.g., "more") -- during their second postnatal year. Math words, as all words, are likely learned in the home setting during interactions with caregivers. However, everyday…

In low- and middle-income countries, urbanization has spurred the expansion of peri-urban communities, or urban communities of formerly rural residents with low socioeconomic status. The growth of these communities offers researchers an opportunity to measure the associations between the level of urbanization and the home language environment…

In this extensively revised edition, Martha Ann Bell and her contributors synthesize the newest research on how cognitive and emotional processes influence each other in child development. Historically, research in child development has treated cognitive processes as separate and distinct from social-emotional processes. However, many of the…

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…

This study compared the acoustic properties of 26 (100% female, 100% monolingual) Danish caregivers' spontaneous speech addressed to their 11- to 24-month-old infants (infant-directed speech, IDS) and an adult experimenter (adult-directed speech, ADS). The data were collected between 2016 and 2018 in Aarhus, Denmark. Prosodic properties of Danish…

A bilingual environment is associated with changes in the brain's structure and function. Some suggest that bilingualism also improves higher-cognitive functions in infants as young as 6-months, yet whether this effect is associated with changes in the infant brain remains unknown. In the present study, we measured brain activity using functional…

We compared speech acts and complexity of maternal speech to firstborn dizygotic twin and singleton infants. Nine twins and nine singletons were video-recorded at home in spontaneous face-to-face interactions with their mothers, from the 2nd to the 6th month. Continuous micro-analysis revealed that (a) open-ended questions, direct requests,…

The present study aimed at investigating the contextual stability, the contextual continuity and the concurrent associations between maternal measures (general language, communicative functions and mind-mindedness) and child measures (total number of word types and tokens) in two different contexts, free-play and mealtime. To this purpose, the…

With the explosive growth in time spent on YouTube by babies and toddlers, it's important to analyze what they're watching on YouTube. Indexes that evaluate the contents of YouTube channels for infants and toddlers have been developed, but since those were evaluation-based indexes of educators and parents, it is difficult to find out what content…

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…

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…

Infants diagnosed with autism spectrum disorder (autism) have difficulty engaging in social communication and interactions with others and often experience language impairment. The use of infant-directed speech (IDS), which is the speech register used when interacting with infants, is associated with infant language and socio-communicative…

Bilingual infants acquire languages in a variety of language environments. Some caregivers follow a one-person-one-language approach in an attempt to not "confuse" their child. However, the central assumption that infants can keep track of what language a person speaks has not been tested. In two studies, we tested whether bilingual and…

Early childhood education and care (ECEC) has been found to be beneficial for the development of children below three years. However, many children do not attend ECEC facilities. Frequently, structural family characteristics (SFC), such as migration background, educational attainment and income, are used to explain differing probabilities of…

Purpose: To investigate the language environments experienced by preterm-born infants, this study compared the linguistic and interactive features of parent--infant conversations involving 2-year-old preterm- and term-born infants. The study also explored how mother-infant and father-infant conversations may be differentially affected by…