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…

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…

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…