Linguistic errors are pervasive in second language (L2) students' writing. Depending on their gravity, the errors may cause a minor degree of irritation to the reader or even lead to total communication breakdown. As such, errors have always been a major concern to both students and teachers, and error correction has also assumed a central position in language teaching. Students generally expect that their errors will be pointed out and dealt with by their teachers. For instance, in a study on students' attitudes toward corrective feedback (CF) in college-level English writing classes, Leki (1991) surveyed 100 English as a Second Language (ESL) students, asking them such questions as how concerned they were with their written errors, what they thought were the most important features in their writing that the teacher should attend to, and what they looked at when receiving a graded paper from the teacher. The results of the survey indicated that the students believed that good writing should be error-free, and the majority wanted all their written errors to be corrected. For L2 teachers, providing written CF on student writing has long been an essential practice. In fact, "grammar correction is something of an institution" (Truscott, 1996, p. 327) in L2 writing courses. Despite the fact that correcting students' written errors is a time-consuming ordeal, and the endeavor is "fraught with uncertainty about its long-term effectiveness" (Ferris, 1999, p. 1), most L2 teachers have continued to slave over students' errors in one form or another. As confirmed by a recent study on practitioners' perspectives, the majority of teachers believe that students need CF and that written CF is overall an effective pedagogical practice (Evans et al., 2010).