Stephen Krashen developed the Input Hypothesis in the 1970s. This model was developed in the wake of Chomsky’s UG. In the beginning Krashen named it “Monitor Model”. He named it “Input Hypothesis” later on.
Krashen’s model is said to be based on the notion that there are two systems for learners of second language acquisition. The first is acquisition and the second is learning. So the learned system in this situation acts as a monitor. Following pictures shows Krashen’s model.
The Five Hypotheses
1. First Hypothesis
In fact, Krashen’s model consists of five hypotheses. This first hypothesis acquisition learning hypothesis. This hypothesis holds that there are different ways for the learners to get competence. For example, one of such ways is the “exposure” in which a learner comes in contact with language through communication and though this communication he/she learns the language competence. In this way, the learner does not have to focus on the process of acquiring. The other way to get competence of language is through conscious exposure to the language. For example, when someone is properly trained to learn the language such as in classrooms.
2. Second Hypothesis
The second hypothesis is the monitor hypothesis. Karashen describes that what the learner has learned acts as a “learned” information or knowledge that monitors or editors what the learner is presently learning. So this monitors is what enables the learners to correct themselves when they utter something that is incorrect.
3. Third Hypothesis
The third hypothesis in his model was “Natural Order Hypothesis”. This hypothesis holds that the elements of a language are learned in a fixed order or in a systematic pattern. This fixed order is said to be pre-determined.
4. Fourth Hypothesis
The fourth hypothesis in the model was “Comprehensible Input Hypothesis”. This hypothesis holds that the best way to get competence in a second language is through exposure to the comprehensible input of that language. If a learners is exposed to enough comprehensible input of the target language, it is essential that the grammar for that language would automatically develop. In his hypothesis, comprehensible input is defined as “i+1”.
5. Fifth Hypothesis
The fifth and the last hypothesis in this model is “Affective Filter Hypothesis”. The affective filter hypothesis holds that the learners have a system for language acquisition. This is the system that UG name as language acquisition device. Therefore, this filter, in some situations affects the access to this device. That is why the acquisition of language is affected. The condition that affect the filter is the emotional conditions of the learners. One of such emotional condition is anxiety.
In conclusion, the Krashen’s Input Model views language acquisition as dependent on sufficient comprehensible input to the target language. When the learner is exposed to the correct language data, the grammar of that language is automatically generated by the innate mental faculty of the human being, which was named as the language acquisition device.