Monitor theory

Not to be confused with the 'monitor hypothesis', one component of monitor theory.

Monitor theory comprises five hypotheses about second language acquisition (SLA) developed by Stephen Krashen: the acquisition-learning hypothesis; the monitor hypothesis; the natural order hypothesis; the input hypothesis; and the affective filter hypothesis.

Monitor theory, as defined by Krashen, states that adult learners have two systems to enable them to develop their language ability: subconscious acquisition and conscious learning, with acquisition being more important. Conscious learning is only available as a "monitor", i.e. learners can consciously 'edit' their 'output' (utterances or written work) to make themselves more fluent or comprehensible, based on what they have formally learned about the second　language. This, however, has no effect on subconscious, true acquisition, and in its absence, output will be less 'accurate' or native speaker-like. Each of the hypotheses relate to conditions that are necessary for acquisition to take place within a system that involves subconscious emergence of language alongside conscious monitoring: for example, the natural order hypothesis points towards a fairly fixed sequence of acquisition that adult language users go through when monitoring does not interfere much, and which is closer to first language acquisition by children.

The model has often proved controversial, though its hypotheses would seem to be supported by many linguists and teachers - e.g. that lots of input is necessary, that there is a difference between acquisition and learning, etc. - it has also been strongly criticised due to the prevailing mood in applied linguistics that learned knowledge does form part of true acquisition.