Growing up with multiple siblings might negatively affect language development. This study examined the associations between birth order, sibling characteristics and parent-reported vocabulary size in 6163 Norwegian 8- to 36-month-old children (51.4% female). Results confirmed that birth order was negatively associated with vocabulary, yet…

Emotion understanding develops rapidly in early childhood. Firstborn children (N = 231, 55% girls/45% boys, 86% White, 5% Black, 3% Asian, 4% Latinx, Mage = 29.92 months) were recruited into a longitudinal study from 2004 to 2008 in the United States and administered a series of tasks assessing eight components of young children's emotion…

Issues of equality and fairness and invasion of the personal domain, 2 previously identified topic areas of adolescent sibling conflict (N. Campione-Barr & J. G. Smetana, 2010), were examined in 145 dyads ("M" [subscript first-born] = 14.97, "SD" = 1.69 years; "M" [subscript second-born] = 12.20,…

Longitudinal data were obtained from 157 children aged 3 years 3 months to 5 years 6 months at Time 1. At Time 2 these children had aged an average of 12 months. Theory of mind (ToM) and executive functioning (EF) were measured at both time points. Results suggest that Time 1 ToM scores predict Time 2 EF scores. Detailed examination of sibling…

The IQ performance of children who experienced the birth of a younger sibling was found to drop 10 points during the next two years for singleton children and 5.8 points for last-born children from families of comparable size. The study controlled for sex, family size, age at assessment, and IQ before the birth of the sibling. (Author/RH)

This study charted the development of gendered personality qualities and activity interests from age 7 to age 19 in 364 first- and second-born siblings from 185 White, middle/working-class families, assessed links between time in gendered social contexts (with mother, father, female peers, and male peers) and gender development, and tested whether…

Results are interpreted in terms of role theory and sibling rivalry, and have application for school practice. (Author)

Patterns of mothering and fathering in 72 families were observed longitudinally and from the perspective of the family system when infants were 1, 3, and 9 months old. Findings suggested similarities and differences in mothering and fathering. (Author/RH)

Used time-lapse video to record sleep/wake states of preterm infants for three 24-hour periods at 33 and 35 weeks conceptional age. Found that very-low-birthweight preterm infants showed marked stability and developmental change in the organization of sleep/wake states from a very early age, and their states were related to demographic variables…

Three studies used interspecies adoption stories to examine children's understanding of the role of birth in determining animal properties and species identity. Found that most 4- to 7-year olds could reliably judge that babies would be of the same species as birth parents, but were unable to attribute properties of adoptive parents. (Author/KB)

Changes in sibling intimacy and conflict were charted from middle childhood through adolescence, and family structure and relationship correlates of change were examined. Participants were mothers, fathers, and firstborn (M=11.82 years at Time 1) and secondborn (M=9.22 years) siblings from 200 White, working/middle class, 2-parent families.…