Note that the model presented here allows us to self-correct using acquired knowledge of language, or our "feel" for grammaticality. That is what native speakers generally do in the case of speech errors. The point is not that we can only monitor using conscious rules. This is not the case. The point is that conscious learning is only available as a Monitor.

In the last few years, the acquisition-learning distinction has been shown to be useful in explaining a variety of phenomena in the field of second language acquisition. While many of these phenomena may have alternative explanations, the claim is that the Monitor Theory provides for all of them in a general, non ad hoc way that satisfies the intuitions as well as the data. The papers in this volume review this research, and include discussion of how the second language classroom may be utilized for both acquisition and learning.

Individual Variation

Chapter 1, based on a paper written in 1976 and published in Ritchie (1978), describes how the learning-acquisition distinction captures one sort of individual variation in second language performance. Based on case histories, this section proposes that there are basically three types of performer:

Monitor "overusers" are performers who feel they must "know the rule" for everything and do not entirely trust their feel for grammaticality in the second language. One case, "S", described by Stafford and Covitt (1978), remarked: "I feel bad... when I put words together and I don't know nothing about the grammar." In Stevicks terms (Stevick, 1976, p. 78), overusers may suffer from "lathophobic aphasia", an "unwillingness to speak for fear of making a mistake".

At the other extreme is the underuser, who appears to be entirely dependent on what he can "pick up" of the second language. Underusers seem to be immune to error correction, and do not perform well on "grammar" test. They may acquire a great deal of the target language, however, and often use quite complex constructions.

The optimal user is the performer who uses learning as a real supplement to acquisition, monitoring when it is appropriate and

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