Second language learning-induced enhancement of executive functions in an instructed language learning context

This study probes the effects of L2 experience on the enhancement of executive functions (EFs) and the predictive validity of EFs for L2 success from a domain-general perspective in a longitudinal pre-test/post-test design. Participants in the experimental group were 165 Turkish high-school graduates receiving intensive L2 instruction in a university setting for six months (600 class contact hours), and the ones in the control group were 103 freshman students taking undergraduate courses in their first language. Two visual complex span tasks (symmetry and rotation) to measure working memory, antisaccade and flanker tasks to measure inhibition, and one standardized English proficiency task were administered before and after the instruction. Multivariate and univariate repeated measures ANOVA results indicated that both instruction types led to the enhancement of EFs except for flanker performances, yet no group differences were observed. Exploratory factor analysis revealed that complex span task and antisaccade performances had loadings on the same factor, named as executive attention, whereas flanker performance was independent from this dimension. Regression findings demonstrated that, albeit little, flanker but not executive attention could explain L2 success. Prior L2 experience was found to be the best predictor. The study concluded that L2 experience can contribute to the enhancement of EFs, yet executive attention might not play a significant role in L2 success at the end of a six-month intensive L2 instruction.