Introduction

This book is concerned with what has been called the "Monitor Theory" of adult second language acquisition. Monitor Theory hypothesizes that adults have two independent systems for developing ability in second languages, subconscious language acquisition and conscious language learning, and that these systems are interrelated in a definite way: subconscious acquisition appears to be far more important.

The introduction is devoted to a brief statement of the theory and its implications for different aspects of second language acquisitions theory and practice. We define acquisition and learning, and present the Monitor Model for adult second language performance. Following this, brief summaries of research results in various areas of second language acquisition serve as both an overview of Monitor Theory research over the last few years and as introduction to the essays that follow.

Acquisition and Learning and the Monitor Model for Performance

Language acquisition is very similar to the process children use in acquiring first and second languages. It requires meaningful interaction in the target language--natural communication--in which speakers are concerned not with the form of their utterances but with the messages they are conveying and understanding. Error correction and explicit teaching of rules are not relevant to language acquisition (Brown and Hanlon, 1970; Brown, Cazden, and Bellugi, 1973), but caretakers and native speakers can modify their utterances addressed to acquirers to help them understand, and these modifications are thought to help the acquisition process (Snow and Ferguson, 1977). It has been hypothesized that there is a fairly stable order of acquisition of structures in language acquisition, that is, one can see clear

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