Longitudinal measurement enables the examination of behavioral or psychological change. One approach to examining longitudinal measurements is the use of latent growth curve modeling (LGCM). This approach affords the assessment of inter- and intraindividual change. Yet, this approach likely is underused in exercise science. The purpose of the…

Learners' self-initiated language learning with mobile technology occurring outside the classroom is often contextualized, heterogeneous, and idiosyncratic. In this study, we propose a time-series clustering methodology for researching informal mobile language learners' learning and development of another language, with a view to unravelling the…

Findings from previous cross-sectional studies showed that while toddlers around their first birthday imitate selectively, that is, they systematically omit some kinds of target action steps or they copy only the goal, but not the means of the modeled actions, older toddlers imitate more exactly. The aim of the present article is to provide…

Identity formation is a key developmental task in adolescence. Although many adolescents in modern societies face issues of identity, there are substantial individual differences in identity exploration and commitment. Little is known about the origins of these individual differences. The current study investigated the genetic and environmental…

This article introduces two sophisticated statistical modeling techniques that allow researchers to analyze systematicity, individual variation, and nonlinearity in second language (L2) development. Generalized linear mixed-effects models can be used to quantify individual variation and examine systematic effects simultaneously, and generalized…

Women are underrepresented in many science, technology, engineering, and mathematics (STEM) majors and in some non-STEM majors (e.g., philosophy). Combining newly gathered data on students' perceptions of college major traits with data from the Education Longitudinal Study of 2002 (ELS:2002), we find that perceived gender bias against women…

Researchers often collect longitudinal data to model change over time in a phenomenon of interest. Inevitably, there will be some variation across individuals in specific time intervals between assessments. In this simulation study of growth curve modeling, we investigate how ignoring individual differences in time points when modeling change over…

In this longitudinal study we examined the stability of general cognitive ability (GCA), as well as heterogeneity and genetic and environmental influences underlying individual differences in change. We investigated GCA from young adulthood through late midlife in 1,288 Vietnam Era Twin Study of Aging participants at ages ~20, ~56, and ~62 years.…

The present study investigated the development of global and domain-specific self-representations in the transition from late childhood to early adolescence and tested whether gender, puberty, and school transition help explain individual differences in change. The study was based on three measurement occasions over 2 years and included 248…

Although spending time in criminogenic settings is increasingly recognized as an explanation for adolescent delinquency, little is known about its determinants. The current study aims to examine the extent to which (change in) self-control and (change in) delinquent attitudes relate to (change in) time spent in criminogenic settings, and the…

This longitudinal study aimed to differentiate between acculturative and developmental processes by (a) comparing levels and change rates in victimization among ethnic German immigrants and native German adolescents in Germany and Russian Jewish immigrants in Israel, and (b) testing whether interindividual differences in victimization among…

Given the sharp increase in rates of depression during adolescence, especially in girls, it is important to identify which youth are at greatest risk across this critical developmental transition. During the present research, we examined whether (a) individual differences in cognition-emotion interaction, as reflected in cognitive control (CC)…

The current study investigated the development of global and domain (academic, physical, same-sex peer relationship, opposite-sex peer relationship) self-esteem from age 10 to 16 in a sample of Mexican-origin adolescents. Participants' (N = 674) responses on the Self-Description Questionnaire (SDQ; Marsh, 2005) II-S showed moderate rank-order…

Drawing on the framework of social domain theory, this multi-method, multi-informant longitudinal study examined whether callous-unemotional (CU) tendencies moderated the association between U.S. 4 to 7 year olds' (n = 135; M[subscript age] = 5.65, 50% male; 75% White) ability to differentiate hypothetical, prototypical moral and conventional…

The developmental science literature is riven with respect to (a) parental similar versus different treatment of siblings and (b) sibling similarities and differences. Most methodologies in the field are flawed or confounded. To address these issues, this study employed a within-family longitudinal design to examine developmental processes of…