This study examined the combined effects of two task complexity levels (i.e., high- and low-complex) and two planning conditions including pre-task planning and on-line planning on Iranian intermediate language learners’ speech production regarding complexity, accuracy, and fluency. To this end, 90 intermediate EFL learners from a language institute in Shiraz were randomly assigned into two control and four experimental groups. At first, the language learners in all groups participated in the speaking pretest. Presented with a series of picture description tasks, the participants were asked to narrate a story. During 10 treatment sessions of picture description task performance, the experimental and control groups attempted different planning time conditions including pre-task planning, online planning, and no-planning along with task complexity levels. Finally, following the last session, the posttest was administered to all participants. The narrations analysis, as well as the results of Mixed between-within groups ANOVAs and a series of one-way ANOVAs, manifested that language learners in the pre-task high complexity group outperformed all other groups in terms of complexity. Moreover, the online low complexity group and online high complexity group outperformed the pre-task planning low complexity, no-planning low complexity, and no-planning high complexity groups regarding accuracy. With regard to fluency, the pre-task planning low complexity group significantly outperformed the no-planning low complexity, no-planning high complexity, and online high complexity groups. It was also concluded that pre-task planning affected language learners’ speech fluency. The implications of the results are also addressed.
