Input, instruction, and feedback in second language acquisition
to participate in a symposium at the Ninth World Congress of the International Association of Applied Linguistics in Greece in April 1990. Organized by the Scientific Commission on Second Language Acquisition, the symposium had as its theme ’Focused input and corrective feedback in second language acquisition’. Earlier versions of the papers by Vivian Cook, Jacquelyn Schachter, Michael Sharwood Smith, and Lydia White were presented at that symposium. At the invitation of Edward Arnold Publishers, those four papers, together with the paper by Sascha Felix and Wilfried Weigl, have been collected in this issue of Second Language Research. The theme of this issue has expanded somewhat beyond that of the symposium to include more general questions about the role of instruction in second language acquisition and the nature of both the internal mechanisms which permit language acquisition to take place and the effect of different types of input in contact with those mechanisms. A particular focus in several of the papers is the question of the sufficiency of so-called ’positive evidence’ (examples of utterances which are grammatical in the target language) for second language acquisition. Some researchers take the position that positive evidence is enough to trigger the learner’s internal mechanisms for second language acquisition. Others argue that ’negative evidence’ (information about which sentences are not grammatical) is also required, at least for the acquisition of some aspects of the target language system. The five papers which make up this collection include three theoretical papers on the role of positive and negative evidence and two