Effect of textual enhancement and explicit rule presentation on the noticing and acquisition of L2 grammatical structures: A meta-analysis

This meta-analysis examines whether two instructional treatments would have a positive effect on grammar "noticing" and/or acquisition in an EFL/ESL context. The instructional treatments represent two examples of input enhancement: textual input enhancement and explicit rule presentation. In order to test the effect of these two treatments, I synthesized and analyzed the results of 45 study reports that addressed these two treatments and that were published between the years of 1980 and 2010. Then, I calculated the effect size of each individual study report and the average effect size of all the study reports using a fixed method meta-analysis approach. The average effect size of the textual enhancement treatment showed a low effect size (d = 0.30) while the average effect size of the explicit rule presentation treatment showed a high effect size (d = 0.93). The study offers some pedagogical implications for ESL/EFL teachers and some suggestions for future researchers.