As young as 3 years old, children rely on a mutual intentionality framework to confer group membership--that is, agreement between a joiner ("I want to be in your group") and group ("We want you to be in our group"). Here, we tested whether children apply this cognitive framework in the context of identity-based groups,…

During human childhood, brain development and body growth compete for limited metabolic resources, resulting in a trade-off where energy allocated to brain development can decrease as body growth accelerates. This preregistered study explores the relationship between language skills, serving as a proxy for brain development, and body mass index at…

Current understanding of how culture relates to the development of children's gender-related peer preferences is limited. To investigate the role of societal acceptance of gender nonconformity, this study compared children from China and Thailand. Unlike China and other cultures where the conceptualization of gender as binary is broadly accepted,…

A range of demographic variables influences how much speech young children hear. However, because studies have used vastly different sampling methods, quantitative comparison of interlocking demographic effects has been nearly impossible, across or within studies. We harnessed a unique collection of existing naturalistic, day-long recordings from…

Spatial thinking is an important predictor of mathematics. However, existing data do not determine whether all spatial sub-domains are equally important for mathematics outcomes nor whether mathematics-spatial associations vary through development. This study addresses these questions by exploring the developmental relations between mathematics…

The study assessed the relations among acuity of the inherent approximate number system (ANS), performance on measures of symbolic quantitative knowledge, and mathematics achievement for a sample of 138 (64 boys) preschoolers. The Weber fraction (a measure of ANS acuity) and associated task accuracy were significantly correlated with mathematics…

Maternal cortisol levels (at 15, 19, 25, 31 and 37 weeks' gestation) and fetal movement response to vibroacoustic stimulation (VAS; at 25, 31 and 37 weeks) were assessed in 190 mother-fetus pairs. Fetuses showed a response to the VAS at 25 weeks and there was evidence of increasing maturation in the response at 31 and 37 weeks. Early elevations in…

There is some evidence for sex differences in habituation in the human fetus, but it is unknown whether this is due to differences in central processing (habituation) or in more peripheral processes, sensory or motor, involved in the response. This study examined whether the sex of the fetus influenced auditory habituation at 33 weeks of…

Early post-natal nutrition influences later development, but there are no studies comparing brain function in healthy infants as a function of dietary intake even though the major infant diets differ significantly in nutrient composition. We studied brain responses (event-related potentials; ERPs) to speech sounds for infants who were fed either…

Auditory processing capabilities at the subcortical level have been hypothesized to impact an individual's development of both language and reading abilities. The present study examined whether auditory processing capabilities relate to language development in healthy 9-month-old infants. Participants were 71 infants (31 boys and 40 girls) with…

This research investigates children's use of social categories in their food selection. Across three studies, we presented preschoolers with sets of photographs that contrasted food-eating models with different characteristics, including model gender, race (Black, White), age (child or adult), and/or expression (acceptance or rejection of the…

Gender schema theory proposes that children's acquisition of gender labels and gender stereotypes informs gender-congruent behaviour. Most previous studies have been cross-sectional and do not address the temporal relationship between knowledge and behaviour. We report the results of a longitudinal study of gender knowledge and sex-typed behaviour…