Longitudinal tracking of 107 three- to-thirteen-year-olds in a cross-sequential design showed a 6-step theory of mind (ToM) sequence identified by a few past cross-sectional studies validly depicted longitudinal ToM development from early to middle childhood for typically developing (TD) children and those with ToM delays owing to deafness or…

Previous research on Montessori preschool education is inconsistent and prone to analytic flexibility. In this preregistered study, disadvantaged preschoolers in a French public school were randomly assigned to either conventional or Montessori classrooms, with the latter being adapted to French public education. Adaptations included fewer…

Naturalistic studies show that children can create language-like communication systems in the absence of conventional language. However, experimental evidence is mixed. We address this discrepancy using an experimental paradigm that simulates naturalistic sign creation. Specifically, we tested if a sample of 6- to 12-year-old children (52 girls…

Using data from 1,571 ninth-grade students (M[subscript age] = 14.62) from 82 academic track schools in Germany and their predominantly Caucasian middle-class parents, configurations of different family characteristics reported by parents were investigated. Latent profile analyses considering academic involvement, family interest, parents'…

This research tests how perceived school and peer norms predict interethnic experiences among ethnic minority and majority youth. With studies in Chile (654 nonindigenous and 244 Mapuche students, M = 11.20 and 11.31 years) and the United States (468 non-Hispanic White and 126 Latino students, M = 11.66 and 11.68 years), cross-sectional results…

Children in all cultures readily engage in artistic activities, yet the arts (dance, drama, drawing, and music) have traditionally been marginal topics in the discipline of developmental science. We argue that developmental psychologists cannot afford to ignore such naturalistic activities that involve so many basic phenomena--attention,…

Although theory of mind (ToM) is argued to emerge between 3 and 5 years of age, data from non-Western, small-scale societies suggest diversity. Deeper investigations into these settings are warranted. In the current study, over 400 Melanesian children from Vanuatu (range = 3-14 years), growing up in either urban or rural remote environments,…

Consecutive retestings of 92 U.S. preschoolers (n = 30), Chinese preschoolers (n = 31), and deaf children (n = 31) examined whether the sequences of development apparent in cross-sectional results with a theory-of-mind scale also appeared in longitudinal assessment. Longitudinal data confirmed that theory-of-mind progressions apparent in…

Relations were examined between children's sleep and their externalizing and internalizing symptoms. Longitudinal relations were examined when children were in 3rd (T1) and 5th (T2) grades, and cross-sectional relations were assessed at T2. Participants included 176 children at T1 (M = 8.68 years) and 141 children at T2 (M = 10.70 years). Sleep…

This meta-analysis summarizes 113 research reports worldwide (121 cross-sectional and 7 longitudinal studies) on age differences in ethnic, racial, or national prejudice among children and adolescents. Overall, results indicated a peak in prejudice in middle childhood (5-7 years) followed by a slight decrease until late childhood (8-10 years). In…

To bridge the social-reasoning focus of developmental research on irony understanding and the pragmatic focus of research with adult populations, this cross-sectional study examines 5-, 7-, and 9-year-olds' (n = 72) developing understanding of both social-cognitive and social-communicative aspects of discourse irony, when compared with adults (n =…

Research on multiracial individuals is often cross-sectional, obscuring the fluid nature of multiracial self-categorization across time. Pathways of racial self-identification are developed from a nationally representative sample of adolescents aged 14-18, measured again 5 years later. A significant proportion of multiracial adolescents change…

Studies using the English and Spanish MacArthur Communicative Development Inventories demonstrated that the grammatical abilities of 20--30-month-old bilingual children were related more strongly to same-language vocabulary development than to broader lexical-conceptual development or maturation. First, proportions of different word types in each…

Paper presented at the meeting of the American Psychological Association, Miami, Florida, September, 1970. (RY)

Three studies (N=144) investigated how toddlers aged 18 and 24 months pass the surprise-mark test of self-recognition. In Study 1, toddlers were surreptitiously marked in successive conditions on their legs and faces with stickers visible only in a mirror. Rates of sticker touching did not differ significantly between conditions. In Study 2,…