“…Some researchers claim that the evidence in favour of corrective feedback is insufficient, but various studies and meta-analyses (Russell and Spada, 2006) tend to indicate that, in general, corrective feedback has a positive effect on language learning. In addition, there are indications that, to be effective, corrective feedback should be unambiguous, consistent, intensive, should provide opportunities for self-repair and modified output (Tatawy, 2002), should not be too asynchronous as it is important to give feedback while the procedural "knowledge" that led to the error is still active in memory (DeKeyser, 2007) and should preferably take account of specific learner characteristics.…”