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The present study is an attempt to investigate whether online dyadic text-based discussion can help language learners develop their oral proficiency due to the fact that classroom interaction barriers have been eliminated and a less threatening, less stressful environment for learner-learner interaction has been created. A total of 30 college freshmen students at the University of Tehran participated in weekly online discussions using the 'Yahoo Messenger' platform for dyadic discussions during six consecutive weeks. The results of participants' oral proficiency test showed that there was a statistically significant difference between the learners' scores in the pre-test and those in the post-test. In addition, the results of both questionnaires and oral proficiency tests employed in the present study showed that online discussion (S-CMC) is more beneficial for the linguistically insecure and shy learners as well as those who had positive attitudes toward online discussion. Moreover, analysis of learners' chat logs regarding the number of turns and number of words per student per session indicated that learners' participation in dyadic online discussion was not equal. This is, in fact, in contrast to what has been reported in previous studies done in this field.

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This pseudo-longitudinal study adopted typical-error and corrective feedback approaches to investigating interlanguage fossilization. The errors in the argumentative essays of 76 Iranian EFL learners within and across three proficiency levels were identified and classified using the model proposed by Gass and Selinker (1994). The learners were first provided with implicit and then explicit feedback to see if the two feedback types would improve written production, and if there were errors that persisted. The results indicated that word choice, plural, word form and article “the” were the most frequent types of errors, with word choice topping the list. The results also showed that, although providing learners with feedback could lead to a reduction in errors, explicit feedback was a more effective strategy. However, the t-test results demonstrated that the short-term impact of feedback could not be sustained over time, a finding congruent with those of Truscott (2007) who questioned the efficacy of error correction. Moreover, the findings revealed that the error categories of pronoun, word order, passive and possessive were likely candidates of fossilization because, although for all the other error types implicit feedback could be beneficial, these showed resistance to correction and needed explicit feedback to be eliminated.