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.

This article examines incidental and transitory focus on form. Learner uptake was studied in focus-on-form episodes occurring in 12 hours of communicative ESL teaching. Learner uptake was generally high and successful-to a much greater extent than has been reported for immersion classrooms. Uptake was higher and more successful in reactive focus on form and in student-initiated focus on form than in teacher-initiated focus on form. The level of uptake was also influenced by whether meaning or form was negotiated and by the complexity of an episode. This study indicates that focus on form can occur without disturbing the communicative flow of a classroom and that the classroom context can affect the amount of uptake.Attention to linguistic forms within the context of performing communicative activities has been termed "focus on form" (Long, 1991). The importance of focusing on form in this way is based on three principal claims about L2 acquisition: (a) learners acquire

Incidental focus on form overtly draws learners' attention to linguistic items as they arise spontaneously—without prior planning—in meaning-focused interaction. This study examined the effectiveness of incidental focus on form in promoting second language (L2) learning. Seventeen hours of naturally occurring, meaning-focused L2 lessons were observed in 12 different classes of young adults in a private language school in Auckland, New Zealand. A total of 491 focus-on-form episodes (FFEs) were identified and used as a basis for individualized test items in which participants who participated in specific FFEs were asked to recall the linguistic information provided in them. The results revealed that learners were able to recall the targeted linguistic information correctly or partially correctly nearly 60% of the time 1 day after the FFE, and 50% of the time 2 weeks later. Furthermore, successful uptake in a FFE was found to be a significant predictor of correct test scores. These results suggest that incidental focus on form might be beneficial to learners, particularly if they incorporate the targeted linguistic items into their own production.This research was supported, in part, by a scholarship from the Foundation for Science, Research, and Technology, New Zealand. The author would like to thank the teachers and participants who kindly gave of their time to participate in this study. The author would also like to thank Rod Ellis, Catherine Elder, Helen Basturkmen, Rosemary Erlam, Jenefer Philp, and the anonymous SSLA reviewers for their valuable input and feedback on this study. Earlier versions of this paper were presented at the annual meeting of the American Association of Applied Linguistics in 2002 (Salt Lake City, UT) and at AILA 2002 (Singapore).

A number of descriptive studies of language classrooms have identified recasts as a frequent form of feedback used by teachers following learners' nontarget-like oral production. Some classroom-based researchers (e.g., Lyster, 1998) have suggested that recasts are less effective than other forms of feedback because of the ambiguity of their potentially corrective purpose. The present study focused on both the provision and the effectiveness of recasts in 12 adult English second language classrooms throughout 17 hours of meaning-based interaction. There were 12 teachers and 118 learners who participated, with class sizes ranging from 6 to 14 students. Comparisons involving the incidence of recasts, elicitation, and metalinguistic feedback, together with learner responses (e.g., successful uptake) following these types of feedback, revealed that recasts were widely used and, similar to other types of corrective feedback, were beneficial at least 50% of the time, as measured by posttests. The recasts differed according to characteristics that emphasized their corrective purpose. Logistic regression analysis revealed certain characteristics that were associated with successful uptake and with accuracy on posttests. Stress, declarative intonation, one change, and multiple feedback moves were predictive of successful uptake, whereas interrogative intonation, shortened length, and one change were predictive of the accuracy of the test scores. This study suggests that recasts vary in implicitness and that these differences may have an impact on their effectiveness, both in terms of learners' successful uptake and subsequent use. Moreover, the ambiguity of recasts is greatly reduced by the phrasal, prosodic, and discoursal cues that teachers provide. The effectiveness of recasts is likely to be affected by these cues and other factors, such as degree of difference between the recast and the nontarget-like utterance.THEORETICAL ARTICLES AND RECENT REviews of empirical research involving instructed second language acquisition (SLA) have provided strong support for the assertion that learners benefit from some kind of focus on linguistic form in classrooms, in addition to meaning-focused communication (Doughty

This article contributes to the growing body of descriptive research investigating focus on form, defined as the incidental attention that teachers and L2 learners pay to form in the context of meaningfocussed instruction. Whereas previous research addressed reactive focus on form (i.e., corrective feedback), the study reported in this article investigated preemptive focus on form (i.e., occasions when either the teacher or a student chose to make a specific form the topic of the discourse). The study found that in 12 hours of meaningfocussed instruction, there were as many preemptive focus-on-form episodes (FFEs) as reactive FFEs. The majority of the preemptive FFEs were initiated by students rather than the teacher and dealt with vocabulary. Students were more likely to uptake a form (i.e., incorporate it into an utterance of their own) if the FFE was student initiated. The preemptive FFEs were typically direct, that is, they dealt with form explicitly rather than implicitly. Despite this, they did not appear to interfere unduly with the communicative flow of the teaching. The article concludes by arguing that preemptive focus on form deserves more attention from classroom researchers than it has received to date.