The role of language aptitude probed within extensive instruction experience: morphosyntactic knowledge of advanced users of L2 English

Abstract This study investigated the role of language aptitude for participants with extensive instructed L2 English learning experience in judging the grammaticality of sentences in auditory and written modalities. Partially replicating a naturalistic L2 learning study, we administered written and auditory grammaticality judgement tests in L2 English and the LLAMA aptitude tests to 37 students at an English-medium state university in Turkey. The participants were divided into higher and lower aptitude groups based on LLAMA scores, and their accuracy/response time scores in early/intermediate/late-acquired structures were examined. The results showed that aptitude was significantly associated with performance only in late-acquired structures in the written modality. Additionally, aptitude distinguished response time rather than accuracy scores, suggesting a qualitative processing difference. The explicit and analytic nature of language aptitude was discussed for adult learners, which is more relevant for the Turkish context where English is taught as a foreign language in academic settings.