This article reviews previous studies of the effects of implicit and explicit corrective feedback on SLA, pointing out a number of methodological problems. It then reports on a new study of the effects of these two types of corrective feedback on the acquisition of past tense -ed. In an experimental design (two experimental groups and a control group), low-intermediate learners of second language English completed two communicative tasks during which they received either recasts (implicit feedback) or metalinguistic explanation (explicit feedback) in response to any utterance that contained an error in the target structure. Acquisition was measured by means of an oral imitation test (designed to measure implicit knowledge) and both an untimed grammaticality judgment test and a metalinguistic knowledge test (both designed to measure explicit knowledge). The tests were administered prior to the instruction, 1 day after the instruction, and again 2 weeks later. Statistical comparisons of the learners' performance on the posttests showed a clear advantage for explicit feedback over implicit feedback for both the delayed imitation and grammaticality judgment posttests. Thus, the results indicate that metalinguistic explanation benefited implicit as well as explicit knowledge and point to the importance of including measures of both types of knowledge in experimental studies.

No abstract

The article reports on a study investigating the comparative effects of immediate and delayed corrective feedback in learning the English past passive construction, a linguistic structure of which the learners had little prior knowledge. A total of 120 learners of English as a foreign language (EFL) from 4 intact classes at a Chinese middle school were randomly assigned to conditions: immediate feedback, delayed feedback, task-only, and control. The 3 experimental groups attended a 2-hour treatment session where they performed 2 dictogloss (narrative) tasks in groups, each followed by a reporting phase in which they took turns telling the narrative to the class. The 2 feedback groups received either immediate or delayed corrective feedback in the form of a prompt, followed by recasts of utterances containing errors in their use of the target structure. No effect for the corrective feedback was found on elicited imitation test scores, but both the immediate and delayed feedback resulted in gains in grammaticality judgment test scores, with immediate feedback showing some advantage over delayed feedback. We interpret these results as showing that the feedback only aided the development of declarative/explicit knowledge and that the advantage found for immediate feedback was due to the learners using the feedback progressively in the production of new past passive sentences, whereas this did not occur in the delayed feedback condition.