Language Acquisition


Comprehension Hypothesis

The comprehension hypothesis, sometimes referred to as input hypothesis, refers to Stephen Krashen’s theory of how language acquisition occurs. This hypothesis claims that the only way language is acquired is through comprehending messages. This hypothesis claims that in order to move from understanding i to i+1 wee need to understand input containing i+1. What this means is that context and previously acquired linguistic knowledge is vital to making new language comprehensible. This hypothesis is often used to refer to all of Krashen’s hypotheses as one entity. These other hypotheses about language include acquisition-learning hypothesis, monitor hypothesis, affective filter hypothesis & the natural order hypothesis.

Acquisition-learning hypothesis

Acquisition-learning hypothesis claims that two independent ways of developing language ability exists: acquisition and learning. While language acquisition is a subconscious process, language learning is what occurs in a classroom setting. It is a conscious process where rules and styles are learned and where error correction occurs.

The natural order hypothesis claims language is acquired in a predictable order. The order in which a first and subsequent languages are learned are similar but not identical. Three facts about this hypothesis:

  1. 1. The natural order is not based on simplicity or complexity. What may seem simple for a linguist may actually take longer to learn than something that a linguist may see as complex.
  2. 2. The natural order cannot be changed. A teacher cannot force a student to learn a grammar rule before the student is ready to acquire it.
  3. 3. The natural order is not the teaching order.

Monitor Hypothesis

The monitor hypothesis asserts that when a learner speaks in a language other than the primary one she/he internally scans, inspects and corrects errors before speaking. This hypothesis claims that self-monitoring and self-correction are the only functions of conscious learning. In order for monitoring to occur three conditions are necessary:

  1. 1. The acquirer must know the rule.
  2. 2. The acquirer must be thinking about correctness or form.
  3. 3. The acquirer must have time.

Monitoring isn’t always feasible not only because the rule must be known ahead of time in order to monitor but also because few people can monitor and converse at the same time, resulting in halting speech or a slow to the flow of conversation.

Affective Filter Hypothesis

The affective filter hypothesis claims that affective variables indirectly impact language acquisition by preventing input from reaching the part of the brain responsible for language acquisition. If the learner is anxious, has low self-esteem or doesn’t see themselves as part of that language group then a block, an affective filter, may keep that learner from having input reach the language acquisition part of the brain even though they may understand that input. Thus a student who isn’t open to input will not make progress in the same manner as a student who is open to the same input.



Krashen, S. (2003). Principles of language acquisition. In Explorations in language acquisition and use. Ann Arbor, MI: Heinemann.

Powell, R., and Davidson, N. (2005). The donut house: Real world literacy in an urban kindergarten classroom. Language Arts, 82(4), 248-256.