Input Hypothesis

The Input Hypothesis is one of five hypotheses of second language acquisition proposed by Stephen Krashen. It is also often used as a catch-all term to refer to all of the hypotheses as one entity. The hypotheses are the acquisition-learning hypothesis, the input hypothesis, the monitor hypothesis, the affective filter, and the natural order hypothesis. They have been very influential in language education, but are not supported by all language acquisition theorists.


Input hypothesis

If i represents previously acquired linguistic competence and extra-linguistic knowledge, the hypothesis claims that we move from i to i+1 by understanding input that contains i+1. Extra-linguistic knowledge includes our knowledge of the world and of the situation, that is, the context. The +1 represents new knowledge or language structures that we should be ready to acquire.[1]

The comprehensible input hypothesis can be restated in terms of the natural order hypothesis. For example, if we acquire the rules of language in a linear order (1, 2, 3...), then i represents the last rule or language form learned, and i+1 is the next structure that should be learned.[2] It must be stressed however, that just any input is not sufficient, the input received must be comprehensible.[1] According to Krashen, there are three corollaries to his theory.

Corollaries of the input/comprehension hypothesis

  1. Talking (output) is not practicing
    Krashen stresses yet again that speaking in the target language does not result in language acquisition. Although speaking can indirectly assist in language acquisition, the ability to speak is not the cause of language learning or acquisition. Instead, comprehensible output is the result of language acquisition.[1][3]
  2. When enough comprehensible input is provided, i+1 is present
    That is to say, that if language models and teachers provide enough comprehensible input, then the structures that acquirers are ready to learn will be present in that input. According to Krashen, this is a better method of developing grammatical accuracy than direct grammar teaching.[1]
  3. The teaching order is not based on the natural order
    Instead, students will acquire the language in a natural order by receiving comprehensible input.[1]

Applications in second language teaching

Beginning level[1]

  • Class time is filled with comprehensible oral input
  • Teachers must modify their speech so that it is comprehensible
  • Demands for speaking (output) are low; students are not forced to speak until ready
  • Grammar instruction is only included for students high school age and older

Intermediate level'[1]

  • Sheltered subject-matter teaching that uses modified academic texts to provide comprehensible input.
  • Sheltered subject matter teaching is not for beginners or native speakers of the target language.
  • In sheltered instruction classes, the focus is on the meaning, and not the form.

Acquisition-learning hypothesis

In modern linguistics, there are many theories as to how humans are able to develop language ability. According to Stephen Krashen's acquisition-learning hypothesis, there are two independent ways in which we develop our linguistic skills: acquisition and learning. [1] This theory is at the core of modern language acquisition theory, and is perhaps the most fundamental of Krashen's theories on Second Language Acquisition.


Acquisition of language is a subconscious process of which the individual is not aware. One is unaware of the process as it is happening and when the new knowledge is acquired, the acquirer generally does not realize that he or she possesses any new knowledge. According to Krashen, both adults and children can subconsciously acquire language, and either written or oral language can be acquired.[1] This process is similar to the process that children undergo when learning their native language. Acquisition requires meaningful interaction in the target language, during which the acquirer is focused on meaning rather than form. [4]


Learning a language, on the other hand, is a conscious process, much like what one experiences in school. New knowledge or language forms are represented consciously in the learner's mind, frequently in the form of language "rules" and "grammar" and the process often involves error correction.[1]. Language learning involves formal instruction, and according to Krashen, is less effective than acquisition.[4]

Monitor Hypothesis

The monitor hypothesis (often spelled Monitor hypothesis) is one of five hypotheses developed by the linguist Stephen Krashen to explain second language acquisition (SLA).


The monitor hypothesis is to part of the Krashen's second language acquisition set of theories comprising :

The acquisition-learning distinction is the most fundamental of these and the most widely known among linguists.

Monitor hypothesis

The monitor hypothesis asserts that a learner's learned system acts as a monitor to what they are producing. In other words, while only the acquired system is able to produce spontaneous speech, the learned system is used to check what is being spoken.

Before the learner produces an utterance, he or she internally scans it for errors, and uses the learned system to make corrections. Self-correction occurs when the learner uses the Monitor to correct a sentence after it is uttered. According to the hypothesis, such self-monitoring and self-correction are the only functions of conscious language learning.[1]

The Monitor model then predicts faster initial progress by adults than children, as adults use this ‘monitor’ when producing L2 (target language) utterances before having acquired the ability for natural performance, and adult learners will input more into conversations earlier than children.[citation needed]

Three conditions for use of the monitor

According to Krashen, for the Monitor to be successfully used, three conditions must be met:

  1. The acquirer/learner must know the rule
    This is a very difficult condition to meet because it means that the speaker must have had explicit instruction on the language form that he or she is trying to produce.[1]
  2. The acquirer must be focused on correctness
    He or she must be thinking about form, and it is difficult to focus on meaning and form at the same time.[1]
  3. The acquirer/learner must have time to use the monitor
    Using the monitor requires the speaker to slow down and focus on form.[1]

Difficulties using the monitor

There are many difficulties with the use of the monitor, making the monitor rather weak as a language tool.

  1. Knowing the rule: this is a difficult condition to meet, because even the best students do not learn every rule that is taught, cannot remember every rule they have learned, and can't always correctly apply the rules they do remember. Furthermore, every rule of a language is not always included in a text nor taught by the teacher [1]
  2. Having time to use the monitor: there is a price that is paid for the use of the monitor- the speaker is then focused on form rather than meaning, resulting in the production and exchange of less information, thus slowing the flow of conversation. Some speakers over-monitor to the point that the conversation is painfully slow and sometimes difficult to listen to.[1]
  3. The rules of language make up only a small portion of our language competence: Acquisition does not provide 100% language competence. There is often a small portion of grammar, punctuation, and spelling that even the most proficient native speakers may not acquire. While it is important to learn these aspects of language, since writing is the only form that requires 100% competence, these aspects of language make up only a small portion of our language competence.[1]

Due to these difficulties, Krashen recommends using the monitor at times when it does not interfere with communication, such as while writing.[1]


The model has been criticized by some linguists and isn't considered a valid hypothesis for some. It has however, inspired much research, and many linguists praise its value.[citation needed]

The theory underlies Krashen and Terrell's comprehension-based language learning methodology known as the natural approach (1983). The Focal Skills approach, first developed in 1988, is also based on the theory.[citation needed] English as a Second Language Podcast was also inspired by Krashen's ideas on providing comprehensible input to language acquirers.

Most popular competitors are the Skill-building Hypothesis and the Comprehensive output hypothesis.[5] The input hypothesis is relate to Instructional scaffolding.

Affective Filter Hypothesis

The affective filter is an impediment to learning or acquisition caused by negative emotional ("affective") responses to one's environment. It is a hypothesis of second language acquisition theory, and a field of interest in educational psychology.

Major components of the hypothesis

According to the affective filter hypothesis, certain emotions, such as anxiety, self-doubt, and mere boredom interfere with the process of acquiring a second language. They function as a filter between the speaker and the listener that reduces the amount of language input the listener is able to understand. These negative emotions prevent efficient processing of the language input.[6] The hypothesis further states that the blockage can be reduced by sparking interest, providing low anxiety environments and bolstering the learner's self-esteem.

According to Krashen (1982)[7], there are two prime issues that prevent the lowering of the affective filter. The first is not allowing for a silent period (expecting the student to speak before they have received an adequate amount of comprehensible input according to their individual needs). The second is correcting their errors too early-on in the process.


Since Stephen Krashen first proposed this hypothesis in the 1970s, a considerable amount of research has been done to test its claims. While the weight of that research is still not definitive, the hypothesis has gained increasing support.

Krashen was not the first to suggest this hypothesis. Dulay and Burt were in 1977, and Krashen made it famous in 1982. This is stated by Krashen himself on page 31 of his book on second language acquisition (1982).

See also


  1. ^ a b c d e f g h i j k l m n o p q r Krashen, S. (2003). Explorations in Language Acquisition and Use. Portsmouth: Heinemann.
  2. ^ Seek information on the acquisition-learning hypothesis to learn more about the differentiations between learning and acquisition
  3. ^ See comprehensible output for more information on output theories and hypotheses
  4. ^ a b Schutz, R. (2007). "Stephen Krashen's Theory of Second Language Acquisition." English Made in Brazil. Available from [1]
  5. ^ Krashen 1989, p. 1
  6. ^ Krashen, S. (2003). Explorations in Language Acquisition and Use. Portsmouth: Heinemann.
  7. ^ Krashen, S. (1982). Principles and practice in second language acquisition. Oxford: Pergamon Press [2]

Further reading

External links

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