an investigation of spoken output and intervention types among iranian efl learners

this study was inspired by vanpatten and uludag’s (2011) study on the transferability of training via processing instruction to output tasks and mori’s (2002) work on the development of talk-in-interaction during a group task. an interview was devised as the pretest, posttest, and delayed posttest to compare four intervention types for teaching the simple past passive: traditional intervention as the comparison group and three task-based groups were processing instruction, consciousness-raising, and input enhancement. the interviews and the interactions during the treatments were also analyzed qualitatively. task-based instruction (tbi) proved significantly more effective than traditional intervention and processing instruction significantly outperformed all others on both posttests. furthermore, processing instruction was the only task-based intervention to retain its improvement till the delayed posttest. qualitatively, processing instruction led to true negotiation of meaning and deep-level learning, consciousness-raising led to massive negotiation over the function of the target structure and deep-level learning, input enhancement led to enormous unfocused interaction about meaning, and traditional intervention just led to interaction about the forms. it was concluded that a well-planned processing instruction is a promising intervention for focusing on language form; however, due to the strong points cited for the other two tasks, their roles should not be ignored.