Abstract
Over the past few decades, task-based language teaching (TBLT) has spawned a series of studies on how various task features affect the way second language (L2) learners use the target language (TL)(e.g., Rostamian, Fazilatfar, & Jabbari, 2018) and acquire TL constructions by carrying out the task (e.g., Solon, Long, & Gurzynski-Weiss, 2017). The theoretical rationale for this strand of research is that task, a meaningful activity that entails TL use to achieve a specified objective (Bygate, Skehan, & Swain, 2001), can engage L2 learners in TL use and hence serve as a viable unit of L2 instruction. As the area has matured with accumulated empirical findings, researchers have commonly identified the near-exclusive attention paid to output-based tasks that entail productive skills such as speaking or writing (Gilabert, Manchón, & Vasylets, 2016). Receptive skills, however, play an important role in task-based instruction, creating opportunities for exposure to new TL features contained in the task input. Shintani (2012) aptly pinpoints the need for more research into input-based tasks that push learners to use the TL to respond to task input, and further asserts that outcome-oriented component can heighten learners’ sensitivity towards new TL features contained in the input and, in doing so, cater for incidental L2 learning. This is an important gap, considering the pervasive use of input-based tasks in many L2 instructional and naturalistic settings (e.g., responding to literature, replying to emails, or filling out a form following an instruction). Another gap in the literature is only marginal attention paid to the effects of task complexity on vocabulary learning. Thus far, target linguistic constructions in the TBLT studies have predominantly been L2 grammatical structures (e.g., Kim, 2012; Révész, Sachs, & Hama, 2014), while the applicability of the task-based approach to L2 vocabulary learning has largely been unattended. Against this background, the present study aimed at filling the gaps in the literature, i.e., the effects of task complexity on L2 learners’ performance in an integrated reading-writing task and learning of vocabulary contained in the task input.