Krashen's monitor model

Based on the Mentalism ( innatism and Universal Grammar) theory of Chomsky, which has great influence on second language acquisition.

Following this theory, Stephen Krashen five hypotheses called the monitor model is used to explain second language acquisition.

1. The Acquisition and Learning Hypothesis.
There are two ways for adult second language learners to develop a knowledge of second language: Acquisition and learning. Acquisition is by picking up the language in the natural environment subconsciously with no conscious while learning is a conscious process of study and attention to the form and rule of the language.
Acquisition is far more important because only acquired language is readily available for natural, fluent communication. Learning cannot turn into acquisition. For example, a speaker may know the rules but fail to apply them while some speakers are fluent without ever learning the rules. Thus attention is focused on what to say than how they are said.

2. The Monitor Hypothesis
Acquisition helps the speaker to be fluent and correct ( accuracy) while learning helps to edit and monitor what has been acquired.
Learners use the monitor only when they are focused more on being correct than on what they have to say.
Knowing the rules only help speakers to supplement what has been acquired thus the focus of language teaching should be on creating conditions for acquisition rather than learning.

3. The Natural Order Hypothesis
This hypothesis explains that Second language learners acquire language in predictable sequence as in first language acquisition.
The rules which are not necessarily the easiest are not necessarily the first to be acquired.
For example, the rule adding -s to third person singular verbs in the present tense is easy to state but even some advanced second language speakers fail to apply it in rapid conversation.

The natural order is independent of the order in which rules have been learned in language classes.

4. The Input Hypothesis

This hypothesis is based on the principle that there is only one way in which people acquire language- By exposure to comprehensible input. Comphrension occurs when the input contains forms and structures just beyond the learner's current level of competence in the language. This Krashen calls i+1.

input is the source of acquisition. Even though some leaners who are exposed to extensive comphrehensible input still do not achieve high level of proficiency in second language.

5. The affective Filter Hypothesis

The affective filter is an imaginary barrier which prevents learners from acquring language from available input.
Affects refers to such things as motives, needs, attitudes, and emotional states.

A learner who is tense, angry, anxious, or bored may filter out input, making it unavailable for acquisition.
Thus depending on the learner's state of mind, the filters limits what is noticed and what is acquired.