Comparative Effects of Recast and Metalinguistic Corrective Feedback in Processing Instruction versus Meaningful Output-based Instruction on the Acquisition of Comparative and Superlative Adjectives

The present study intended to investigate the possible effects of two different types of implicit and explicit corrective feedback (recast and metalinguistic corrective feedback) and two types of grammar instruction, that is Processing Instruction (PI) as an input- based approach and Meaningful Output- Based Instruction (MOBI) with output orientation on learners ' acquisition of comparative and superlative adjectives. To this end, 120 participants selected out of 140 Iranian freshman EFL learners, who had taken the pre-university English course, took part in the study. They were assigned into two main instructional groups (PI/ MOBI), each divided into two subgroups, one exposed to metalinguistc corrective feedbac