Graduate Program in English Language Education.Yalçın, Şebnem.Aktaş Smith, Tuğçe Betül.2025-04-142025-04-142023Graduate Program in English Language Education. CSE 2023 S87 (Thes EE 2023 G86https://digitalarchive.library.bogazici.edu.tr/handle/123456789/21684Task-based language learning and teaching (TBLT) research has shown that task design can be cognitively manipulated to impact second language (L2) performance and create unique opportunities for exploiting different aspects of L2 performance. There are two influential hypotheses on this matter: the Cognition Hypothesis (Robinson, 2001a, 2011a) and the Limited Attentional Capacity Hypothesis (Skehan, 1998, 2009). While the former account predicts a concurrent increase in L2 complexity and accuracy during complex tasks, the latter model suggests a competition over attentional resources leading to the prioritization of certain aspects of L2 performance. Both accounts offer a valuable contribution to cognitively driven task-based research. However, it remains an open empirical question whether these predictions can be applied to written performance and how L2 performance is affected by the interplay of task complexity and modality (speaking versus writing). Therefore, this study examines separate and combined effects of task complexity and task modality on learners’ syntactic and lexical complexity, and accuracy. The results revealed significant differences between writing and speaking in the aspects of phrasal complexity and lexical complexity. Further, a significant interaction was found between modality and task complexity for unit accuracy. The findings indicate that the effects of task complexity differ in writing and speaking, providing insights into the discussion of whether current task complexity models can account for both writing and speaking. Further, combining task complexity and modality can offer learners excellent opportunities for exploiting different aspects of L2 performance.Language learning and language teaching.Second language acquisition.xii, 162 leaves