linguistic performance, especially different aspects of production. However, the findings of these studies have not been conclusive; they suggest that more complex tasks positively impact linguistic performance in general, yet more specific findings related to both accuracy and syntactic complexity only partially supported the cognition hypothesis (e.g., promoting either complexity or accuracy). In Iran, there is not enough opportunity to be exposed to the English language due to the fact that English is not used outside the classroom; therefore, it is up to teacher, syllabus designers, and materials developers to provide tasks with different conditions and characteristics to fill this gap. However, this purpose required a lot of research. This study might be a good contribution to them in this regard. The significance of this study is that task conditions and features exert an influence on directing attention towards the formulation processes. This demonstrates the significance of investigating task conditions and their impact on attention while L2 writing being accomplished. Nonetheless, some task conditions, due to various unknown reasons, have not received the attention they deserved, and one of them is + single task from Robinson's (2005) framework. The main strong claim of this approach is that it can activate the cognitive and acquisitional processes while learners are busy performing tasks and accomplishing their goals (Skehan, 2003). Recently, the effect of task characteristics on learners' language production and development is hotly debated (