This study investigated L2 Korean speakers' self-assessment of speech comprehensibility and accentedness, including a conceptual replication of Trofimovich, Isaacs, Kennedy, Saito, and Crowther (2016, Experiment 1) and exploratory analyses of individual differences in self-assessment. L2 Korean speakers (N = 198) self-assessed their…

Over the past decade, the LLAMA language aptitude test battery has come to play an increasingly important role as an instrument in research on individual differences in language development. However, a potentially serious problem that has been pointed out by several scholars is that the LLAMA has not yet been carefully validated. We addressed this…

Language aptitude has been hypothesized as a factor that can compensate for postcritical period effects in language learning capacity. However, previous research has primarily focused on instructed contexts and rarely on acquisition-rich learning environments where there is a potential for massive amounts of input. In addition, the studies…

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…