Social anxiety is a common mental disorder with an average age of onset in early adolescence. Current theories focus largely on risk factors that are present from early in life, but reasons for onset of the disorder as youth move into adolescence are rarely discussed. We recently proposed a model of the onset of certain mental disorders during the…

Exposure to deviant friends has been found to be a powerful source of influence on children's and adolescents' aggressive behavior. However, the contribution of deviant friends may have been overestimated because of a possible non-accounted gene-environment correlation (rGE). In this study, we used a cross-lagged design to test whether friends'…

The aim of this study was to disentangle pervasive from situational antisocial behaviors using multiple informants, and to investigate their genetic and environmental etiologies in preadolescence and across time. Antisocial behaviors were assessed in 2,232 twins from the Environmental Risk (E-Risk) Longitudinal Twin Study at ages 5 and 12.…

We analyzed developmental changes in outsider behavior, testing whether the likelihood that it turns into bullying or defending over time depends on the individual proneness to feel shame or guilt. Participants were 155 preadolescents (72 boys and 83 girls; [X-bar][subscript age] at T1 = 10.74 years). Bullying, defending, and outsider behaviors…

Purpose: The purpose of this study was to analyze tracking and stability of motor coordination in children from age 6 years to ages 9 and 13 years. Method: Data were from the Copenhagen School Child Intervention Study. Motor coordination (MC) was measured using the körperkoordinationstest für Kinder (KTK) test. The crude performance score on every…

This longitudinal research examines maternal and child behaviors during joint planning over a 3-year period of middle childhood. 118 mother-child dyads were observed once a year beginning when the children were 8 years of age. Coding focused on mother and child planning behaviors, maternal instructional support, and child task engagement.…

The dramatic decline in youth interest in science, technology, engineering and mathematics (STEM) during adolescence, both in the USA and internationally, has been a phenomenon of societal concern for several decades. The Synergies project was launched to help deal with this issue. In this paper, we report findings from the first two years of our…

This longitudinal case study of a 10-year-old girl with autism and severe communication impairment measures the impact of the MORE (Means, Opportunities, Reasons and Expectations) approach to enhancing engagement and communication. Through detailed observation of video data over a period of 28 months, engagement behaviours including interaction…

We examined children's sleep at age 9 as a predictor of developmental trajectories of cognitive performance from ages 9 to 11 years. The effects of sleep on cognition are not uniform and thus we tested race/ethnicity, socioeconomic status (SES), and sex as moderators of these associations. At the first assessment, 282 children aged 9.44 years (52%…

Although Erikson (1968) originally conceptualized identity development as a process of becoming at home in one's body, little work has been done linking identity development and research on the body. This study examines how trajectories of the development of body esteem over time are related to young people's sense of identity and psychological…

Learners' academic self-concepts and attributions have been widely evidenced to substantially regulate their educational development. Developmentally, they will not only operate in a mutually reinforcing manner. Rather, self-concepts will directly affect learners' outcome attributions in a particular academic setting. Current research in the…

Extant literature has established a consistent association between aspects of reading motivation, such as enjoyment and self-perceived ability, and reading achievement, in that more motivated readers are generally more skilled readers. However, the developmental etiology of this relation is yet to be investigated. The present study explores the…

Background: The basis of self-perceived physical competence is built in childhood and school personnel have an important role in this developmental process. We investigated the association between initial self-perceived physical competence and reported leisure-time physical activity (LTPA) longitudinally in 10-, 12-, and 15-year-old children.…

The purpose of this study was to examine time-varying associations of parent-adolescent cultural conflict with depressive symptoms and grade point average (GPA) among Chinese Americans from ages 11-22. We pooled two independently collected longitudinal data sets (N = 760 at Wave 1) and used time-varying effect modeling (TVEM) to show that the…

Romantic relationship quality in adolescence and early adulthood has often been linked to earlier parent-child relationship quality but it is possible that these links are nonlinear. Moreover, the role of social skills as mediator of associations between parent-child and romantic relations has been discussed but not rigorously tested. Using data…