LAUSR

Abstract The present study investigates the role of different planning conditions, cognitive task complexity along ± number of elements, and different task types in learners’ L2 oral performance. To this end, 98 Iranian learners at the intermediate level were randomly divided into four planning groups, namely, task repetition, strategic planning, joint planning (a combination of task repetition & strategic planning), and no planning. Each group performed simple and complex narrations and simple and complex argumentations. The data were scored based on measures of complexity, accuracy, lexical diversity, and fluency. The results indicated that in comparison with the simple tasks, the complex tasks promoted fluency, overall complexity, and lexical complexity, but lessened accuracy and subordination. Compared to the narrations, the argumentations brought about higher speech rate, more subordinated clauses, and greater lexical complexity. Strategic planning and task repetition enhanced fluency and syntactic complexity while their combination improved accuracy as well. The impact of task complexity was greater with the argumentations, and the utility of planning differed based on cognitive task complexity and the nature of task types. Some trade-offs were observed not only between accuracy and syntactic complexity but also between two measures of syntactic complexity, which supports the Trade-off Hypothesis.