Combined Effect of the Phase of Explicit Instruction and Feedback Timing on Task Performance and Grammar Acquisition

This study investigated the combined effect of the phase of explicit instruction and feedback timing on task performance and grammar acquisition. Fifty pre-intermediate learners were randomly assigned to 3 major conditions and 5 sub-conditions: pre-task explicit instruction with either immediate or delayed feedback, main-task explicit instruction with either immediate or delayed feedback, and control group. All groups were given a grammaticality judgment test (GJT) and an elicited imitation test (EIT) as the pre- and post-test. During the treatment period, the 4 experimental groups completed three tasks within three weeks. The third task was analyzed for task performance (CAF). The results indicated that among groups, the pre-task/immediate group was the most fluent group and that they had the most attempts to use the target form as much as main task/delayed group. The pre-task/delayed group produced the longest units with highest accuracy and most correct use of the target form.  However, none of the differences were significant except for pre-task (the group that received explicit instruction before task completion) and delayed feedback group which statistically produced longer units and made fewer errors compared to the control group. Additionally, the groups which received explicit instruction within the task completion (main task with either immediate or delayed feedback) statistically made fewer errors than the control group. Regarding performance on GJT and EIT, although pre-task/immediate group gained the highest scores, the differences were not statistically significant. It can be concluded that providing explicit instruction of structure before task with delayed feedback can benefit task performance in terms of complexity and accuracy, and providing explicit instruction within task completion with either immediate or delayed feedback to promote accuracy.