The Monitor Hypothesis

While the acquisition-learning distinction claims that two separate processes coexist in the adult, it does not state how they are used in second language performance. The monitor hypothesis posits that acquisition and learning are used in very specific ways. Normally, acquisition “initiates” our utterances in a second language and is responsible for our fluency. Learning has only one function, and that is as a monitor, or editor. Learning comes into play only to make changes in the form of our utterance, after it has been “produced” by the acquired system. This can happen before we speak or write, or after (self-correction).
The monitor hypothesis implies that formal rules, or conscious learning, play only a limited role in second language performance. These limitations have become even clearer as research has proceeded in the last few years. This research suggests that second language performers can use conscious rules only when three conditions are met. These conditions are necessary and not sufficient, that is, a performer may not fully utilize his conscious grammar even when all three conditions are met. Those three conditions are:

a) Time
In order to think about and use conscious rules effectively, a second language performer needs to have sufficient time. For most people, normal conversation does not allow enough time to think about and use rules. The over-use of rules in conversation can lead to trouble (a hesitant style of talking and inattention to what the conversational partner is saying).

b) Focus on form
To use the monitor effectively, time is not enough. The performer must also be focused on form, or thinking about correctness. Even when we have time, we may be so involved in what we are saying that we do not attend to how we are saying it.

c) Know the rule
This is a very formidable requirement. Linguistics has taught us that the structure of language is extremely complex, and they claim to have described only a fragment of the best known languages. We can be sure that our students are exposed only to a small part of the total grammar of the language, and we know that even the best students do not learn every rule they are exposed to.

There are some differentials uses of the conscious monitor. Krashen suggests that there may be three basic types of performer.

a) Monitor Over-Users
These are people who attempt to monitor all the time, performers who are constantly checking their output with their conscious knowledge of the second language. As a result, such performers may speak hesitantly, often self-correct in the middle of utterances, and are so concerned with correctness that they cannot speak with any real fluency.
There are may be two different causes for over-user of the grammar. Over-user may first of all drive from the performer’s history of exposure to the second language. Many people, victims of grammar-only type of instruction, have simply no had the chance to acquire much of the second language, and may have no choice but to be dependent on learning. Another type may be related to personality. These over-users have had a chance to acquire, and may actually have acquired a great deal of the second language. They simply do not trust this acquired competence and only feel secure when they refer to their monitor “just to be sure”.

b) Monitor Under-Users
These are performers who have not learned, or if they have learned, prefer not to use their conscious knowledge, even when conditions allow it. Under-users are typically uninfluenced by error correction, can self correct only by using “feel” for correctness and rely completely on the acquired system.

c) The Optimal Monitor Users
Our pedagogical goal is to produce optimal users, performers who use the monitor when it is appropriate and when it does not interfere with communication. Many optimal users will not use grammar in ordinary conversation, where it might interfere. In writing, and in planned speech, however, when there is time, optimal users will typically make whatever correction they can to raise the accuracy or their output.
Optimal monitor users can therefore use their learned competence as a supplement to their acquired competence. Some optimal users who have not completely acquired their second language, who make small and occasional errors in speech, can use their conscious grammar so successfully that they can often produce the illusion of being native in their writing. This does not imply that conscious learning can entirely make up for incomplete acquisition. Some unacquired rules will be learnable and other not. The optimal user is able to fill part of the gap with conscious learning, but not all of it.

Taken from: Krashen, S. (1982). Principles & Practice in Second Language Acquisition. Pergamon Press Inc. p.15-20