This paper examines evidence for relationships among individual differences (IDs) in L1 achievement, L2 aptitude, and L2 achievement. It begins by providing an overview of my academic journey from L1 educator to L2 researcher and explains the development of the Linguistic Coding Differences Hypothesis (LCDH). Next, I review Peter Skehan's…

Using key constructs from sociocultural theory and activity theory, this paper outlines three broad areas of future research on written corrective feedback (WCF) that may be of interest to second language (L2) researchers and practitioners. The first area uses the constructs of the Zone of Proximal Development (ZPD) and scaffolding to assess the…

Salthouse (2011) critically reviewed cross-sectional and longitudinal relations among adult age, brain structure, and cognition (ABC) and identified problems in interpretation of the extant literature. His review, however, missed several important points. First, there is enough disparity among the measures of brain structure and cognitive…

Longitudinal studies are necessary to examine individual change over time, with group status often being an important variable in explaining some individual differences in change. Although sample size planning for longitudinal studies has focused on statistical power, recent calls for effect sizes and their corresponding confidence intervals…

A great deal of research into second-language (L2) development focuses on the role of cognitive factors and other individual differences. Studies of children and prime-of-life adult L2 learners suggest that differences exist in the learning processes of these groups. However, to date, little empirical work has been conducted with older adult…

In this article, I describe studies conducted over 25 years with secondary and post-secondary L2 learners in the United States. The evidence from these studies shows that there are important connections between students' early L1 skills and their L2 aptitude and L2 proficiency and that individual differences in students' L1 skills in elementary…

Robert E. Ployhart, recipient of the Award for Distinguished Scientific Early Career Contributions to Psychology, is cited for innovative work in examining reactions to staffing practices and efforts to enhance the acceptability of recruitment and staffing practices; for exemplary use of applied statistical models in examining multilevel effects…

In this study of the origins of individual differences in theory of mind (ToM), the Environmental Risk (E-Risk) Longitudinal Twin Study sample of 1,116 sixty-month-old twin pairs completed a comprehensive battery of ToM tasks. Individual differences in ToM were striking and strongly associated with verbal ability. Behavioral genetic models of the…

Findings are presented from an ecologically grounded, longitudinal study of 206 urban, ethnic minority adolescents that used hierarchical linear modeling to examine: (1) individual trajectories of change in adolescents' perceptions of general and closest same-sex friendship quality from middle to late adolescence; (2) the effects of gender and…

Researchers in the fields of cognitive and language development have made less use of large-scale longitudinal designs and of person-centered approaches to data analysis than have researchers in the fields of social and personality development. It is argued that differences among domains of developmental psychology in the research methods employed…

Data from the fourth followup to the National Education Longitudinal Study of 1988 suggest greater complexity in the individual trajectories, or careers, that characterize the movement from adolescence to adulthood than in earlier years. Understanding the role schooling now plays in the lives of U.S. adults may require a more expansive view than…

Highlights three longitudinal studies examining the hypothesis that attachment security during infancy influences individual differences and adult representations of attachment. Notes that attachment security was significantly stable in two studies, with discontinuity in all three studies related to negative life events and circumstances.…

Multilevel modeling allows for the simultaneous analysis of data gathered at more than 1 unit of analysis (e.g., children nested in schools). It is often used to examine the effects of various contexts on individual differences in change. This paper promotes the application of multilevel models to longitudinal dyadic data in family research. By…

This special issue of the Mensa Research Journal contains four papers written by K. Warner Schaie, a psychologist who focuses on psychological development from young adulthood through old age. The first paper is "Living with Gerontology." In it, Schaie recounts his own childhood, adolescence, and young adulthood, his path to becoming a…

Many educational questions of research interest focus on individual differences in attitudes and behaviors related to academic achievement, changes in such attitudes and behaviors over time, and the types of academic environments that facilitate or prevent development of achievement attitudes and behaviors at school. This paper, the first in a…