Stephen D. Krashen promoted five hypotheses about second language acquisition in his Principles and Practice in Second Language Acquisition published in 1982. His hypotheses have caused great attention and argument from the first day of its publication. Although there are a lot of debates on these hypotheses, it is still the most influential theory in foreign or second language learning. The five hypotheses are 1) Acquisition-learning distinction, 2) The natural order hypothesis, 3) The monitor hypothesis, 4) The input hypothesis, 5) The affective filter hypothesis. The input hypothesis is the most important one both in theoretical and practical aspects.
Input hypothesis attempts to answer the most important question in second language acquisition. That is “How do we acquire language?” We acquire when we understand language that contains structure that is “a little beyond” where we are now. It is a paradox but we can make it possible by using more than our linguistic competence to help us understand. We can use context, our knowledge of the world, and our extra-linguistic information to help us understand language directed at us. The statements of the input hypothesis (Krashen, 1982:22-24)[1] are:
- 1.
The input hypothesis relates to acquisition, not learning;
- 2.
We acquire by understanding language that contains structure a bit beyond our current level of competence (I + 1). This is done with the help of context or extra-linguistic information;
- 3.
When communication is successful, when the input is understood and there is enough of it, I + 1 will be provided automatically;
- 4.
Production ability emerges. It is not taught directly.
The further explanation will be given in the following part.
The input hypothesis relates to acquisition not learning. The distinction of learning and acquisition is most fundamental in Krashen’s all hypotheses. It states that adults have two distinct and independent ways of developing competence in a second language.
The first way is language acquisition. It is a process similar to the way children develop ability in their first language. It is a subconscious process. Language acquirers are not usually aware that they are acquiring language, but are only aware of that they are using the language for communication. The result of language acquisition is also subconscious. Language users have a feel for correctness. Grammatical sentences sound right, or feel right, and errors feel wrong, even if language users do not consciously know what rule was violated. The second way to develop competence in a second language is by language learning. The term “learning” is henceforth used to refer to conscious knowledge of a second language, knowing the rules, being aware of them, and being able to talk about them. In second language learning term, learning is a mental process knowing about a language, in form of grammar or rules. Acquisition is a very powerful process in the adult. It is the only way to help adults to achieve native-like level. The input hypothesis is based on the process of language acquiring but not learning.
People acquire by understanding language that contains structure a bit beyond their current level of competence (I + 1). This is done with the help of context or extra-linguistic information. In this part Krashen emphasized the comprehensible input with the level of I+1. It has some implications. Firstly, the input must be comprehensible. Long [2](1982: 341) initially suggested four ways to make input comprehensible by modifying oral or written input, providing linguistic and extra linguistic context, orienting the communication to the simple form, and modifying the interactional structure of the conversation. On the basis of this argumentation, Park (2002: 2-3)[3] summarized three linguistic environments as the potential sources of comprehensible input for L2 acquisition: (1) premodified input—the linguistic environment where input has been modified in some way before the learner sees or hears it; (2) interactionally modified input—the linguistic environment where a native speaker (NS) or a more competent non-native speaker (NNS) interacts with an NNS, and where both parties modify and restructure the interaction to arrive at mutual understanding; and (3) modified output—the linguistic environment where a learner modifies his/her output to make it more target like and more comprehensible to the interlocutor. It is necessary to clarify that a learner’s modified output can serve as another learner’s comprehensible input. Secondly, I+1 model;All acquirer can move from a stage I (where I is the acquirer’s level of competence) to a stage I+1 (where I+1 is the stage immediately following I along some natural order) by understanding language containing I+1 (Krashen and Terrell 1983:32)[4]. Thirdly, we can acquire the input with the help of the situation, context and extralinguistic information.
When communication is successful, when the input is understood and there is enough of it, I + 1 will be provided automatically. It says that if the acquirer understands the input, and there is enough of it, I + 1 will automatically be provided. This implies that the best input should not even attempt to deliberately aim at I + 1. We are all familiar with syllabi that try to deliberately cover I + 1. Usually both teacher and student feel that the aim of the lesson is to teach or practice a specific grammatical item or structure. Once this structure is “mastered”, the syllabus proceeds to the next one. This part of the input hypothesis implies that such a deliberate attempt to provide I + 1 is not necessary. And there are reasons to suspect that it may even be harmful. This part emphasizes the importance of quantity. There must be a sufficient quantity of comprehensible input to ensure production emerge automatically.
Production ability emerges. It is not taught directly. Speaking fluency cannot be taught directly. Rather, it emerges over time, on its own. The best way, and perhaps the only way, to make a native-like speech, according to this hypothesis, is simply to take in enough comprehensible input. Speech will come when the acquirer feels “ready”. For different acquirers this readiness state arrives at different times. Moreover, the early speech is always not grammatically accurate. Accuracy develops over time as the acquirer hears and understands more input.
Since some implication of the input hypothesis has been discussed, it is time to come to the brief introduction of computer assisted language learning to see how it can help to further explain the input hypothesis.