The Effect of Comprehensible Input and Comprehensible Output on the Accuracy and Complexity of Iranian EFL Learners’ Oral Speech

Document Type : Research Paper


Islamic Azad University, Najafabad Branch


This study aimed at investigating the relative impact of comprehensible input and comprehensible output on the development of grammatical accuracy and syntactic complexity of Iranian EFL learners’ oral production. Participants were 60 female EFL learners selected from a whole population pool of 80 based on the standard test of IELTS. To investigate the research questions, the participants were randomly divided into three groups: Input group, output group, and control group. The study involved two phases: the pre-task phase, and the main-task phase. During the pre-task phase, the input group received comprehensible input. In the same phase, the output group was pushed to be engaged in comprehensible output production. The control group neither received input, nor was engaged in output production. In the main-task phase, all subjects performed monologues that were separately recorded, and later transcribed and coded in terms of accuracy and complexity through Bygate's (2001) standard coding system and finally scored. The statistical analysis of the results revealed that while the output group outperformed the input group in grammatical accuracy, the input group proved to be more rigorous and influential in developing speech complexity. The study supports Swain’s (1985) claim that there are roles for comprehensible output that are different from and independent of comprehensible input, and Skehan & Foster's (2001) theory regarding human beings’ limited attentional capacities that can be devoted to one aspect of oral speech at the expense of the other. Generally, it is implied that the most effective way for improving oral speech, based on the literature and the results obtained from this study, is an eclectic approach which conflates both comprehensible input and comprehensible output.


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