The Optimal Input Hypothesis: Not All Comprehensible Input is of Equal Value.

Stephen Krashen and Beniko Mason

A popular assumption is that any kind of input we provide in class is acceptable as long as it provides some comprehensible input. Thus, we can teach songs, put on a play, and lead the students in exercises, because they all involve some comprehension of messages.

This is not correct. Comprehensible is not enough. There are other factors that make up “optimal input.”

We present here the Optimal Input Hypothesis. (1)

Optimal input has these four characteristics:

It is comprehensible. This does not mean full transparency. Language acquisition does not require understanding every word and every part of every word. Input can be quite comprehensible and useful for acquisition even if there is some “noise” in the input, some incomprehensible bits.
It is very interesting: it is “compelling,” so interesting that you temporarily forget that you are listening to or reading in another language. If input is comprehensible and compelling, acquirers will often not notice noise in the input.
Optimal input is rich in language that contributes to the message and the flow of the story or text. The language included in the input also gives the reader support in understanding and therefore acquiring new aspects of language.
Language acquisition is a gradual process: Each time we encounter a new item in a comprehensible context we acquire a small amount of the meaning (and form). Optimal input must therefore be abundant, providing numerous opportunities for acquisition of new language.

It is not necessary to make sure that certain grammar and vocabulary are used: Rich and abundant comprehensible input will always include a sufficient quantity of new, unacquired language that acquirers are ready to acquire (i+1).

What kinds of input can satisfy the four features comprehensible, compelling, rich and abundant?

Stories. Beniko Mason has shown how stories that contain unacquired language can be made more comprehensible with the use of Comprehension Aiding Supplementation (Krashen, Mason, and Smith, 2018). Comprehension Aiding Supplementation includes drawing pictures, brief translation, and the use of context.

“Story-Listening” teachers do not ask that students try to remember the new language, but studies show that when new language is included in interesting stories, listening to the stories and using Comprehension Aiding Supplementation helps students remember the new items better than doing traditional “study.”

Such input is far more interesting and rich than language found in textbooks, and we have all experienced the compelling nature of stories.

Reading, especially fiction: Mason (2019) has shown how reading can be made comprehensible for low-intermediate level readers when teachers help in book selection (in terms or interest and difficulty). Mason has also insured abundance in her programs: Mason’s EFL students in Japan had access to 5000 graded readers in English, insuring.

The goal of the two stages described here is to bring students to the level where they can read and enjoy “authentic” texts that they select themselves so they can improve on their own.

If the Optimal Input hypothesis is correct, it means that contrary to popular opinion, “immersion,” living in the country where the language is spoken, is sometimes helpful and sometimes not: For acquirers to make maximum progress in immersion situations, the linguistic situation needs to be consistent with the characteristics presented above, which is often not the case (for an example see Mason and Krashen, 2019). Similarly, methods that are advertised as “comprehension-based” may nor may not meet the requirements of optimal input.

1. The optimal input hypothesis assumes we acquire from input, not from output, and results in subconscious language acquisition.

Krashen, S., Mason, B., and Smith, K. 2018. Some new terminology: Comprehension-Aiding Supplementation and Form-Focusing Supplementation.

Journal of English Language Teaching 60(6), 12-13. https://tinyurl.com/y7zbem9g
Mason, B. 2019. Guided SSR before Self-Selected Reading Shitennoji University Journal, 67, 445-456.

Mason, B., and Krashen, S. (2019). Hypothesis: A class supplying rich comprehensible input is more effective and efficient than “Immersion.” IBU Journal of Educational Research and Practice, 7, 83-89. https://tinyurl.com/y4zdwmmz


The Optimal Input Hypothesis: Not All Comprehensible Input is of Equal Value. Stephen Krashen and Beniko Mason A popular assumption is that any kind of input we provide in class is acceptable as long as it provides some comprehensible input. Thus, we can teach songs, put on a play, and lead the students in exercises, because they all involve some comprehension of messages. This is not correct. Comprehensible is not enough. There are other factors that make up “optimal input.” We present here the Optimal Input Hypothesis. (1) Optimal input has these four characteristics: It is comprehensible. This does not mean full transparency. Language acquisition does not require understanding every word and every part of every word. Input can be quite comprehensible and useful for acquisition even if there is some “noise” in the input, some incomprehensible bits. It is very interesting: it is “compelling,” so interesting that you temporarily forget that you are listening to or reading in another language. If input is comprehensible and compelling, acquirers will often not notice noise in the input. Optimal input is rich in language that contributes to the message and the flow of the story or text. The language included in the input also gives the reader support in understanding and therefore acquiring new aspects of language. Language acquisition is a gradual process: Each time we encounter a new item in a comprehensible context we acquire a small amount of the meaning (and form). Optimal input must therefore be abundant, providing numerous opportunities for acquisition of new language. It is not necessary to make sure that certain grammar and vocabulary are used: Rich and abundant comprehensible input will always include a sufficient quantity of new, unacquired language that acquirers are ready to acquire (i+1). What kinds of input can satisfy the four features comprehensible, compelling, rich and abundant? Stories. Beniko Mason has shown how stories that contain unacquired language can be made more comprehensible with the use of Comprehension Aiding Supplementation (Krashen, Mason, and Smith, 2018). Comprehension Aiding Supplementation includes drawing pictures, brief translation, and the use of context. “Story-Listening” teachers do not ask that students try to remember the new language, but studies show that when new language is included in interesting stories, listening to the stories and using Comprehension Aiding Supplementation helps students remember the new items better than doing traditional “study.” Such input is far more interesting and rich than language found in textbooks, and we have all experienced the compelling nature of stories. Reading, especially fiction: Mason (2019) has shown how reading can be made comprehensible for low-intermediate level readers when teachers help in book selection (in terms or interest and difficulty). Mason has also insured abundance in her programs: Mason’s EFL students in Japan had access to 5000 graded readers in English, insuring. The goal of the two stages described here is to bring students to the level where they can read and enjoy “authentic” texts that they select themselves so they can improve on their own. If the Optimal Input hypothesis is correct, it means that contrary to popular opinion, “immersion,” living in the country where the language is spoken, is sometimes helpful and sometimes not: For acquirers to make maximum progress in immersion situations, the linguistic situation needs to be consistent with the characteristics presented above, which is often not the case (for an example see Mason and Krashen, 2019). Similarly, methods that are advertised as “comprehension-based” may nor may not meet the requirements of optimal input. 1. The optimal input hypothesis assumes we acquire from input, not from output, and results in subconscious language acquisition. Krashen, S., Mason, B., and Smith, K. 2018. Some new terminology: Comprehension-Aiding Supplementation and Form-Focusing Supplementation. Journal of English Language Teaching 60(6), 12-13. https://tinyurl.com/y7zbem9g Mason, B. 2019. Guided SSR before Self-Selected Reading Shitennoji University Journal, 67, 445-456. Mason, B., and Krashen, S. (2019). Hypothesis: A class supplying rich comprehensible input is more effective and efficient than “Immersion.” IBU Journal of Educational Research and Practice, 7, 83-89. https://tinyurl.com/y4zdwmmz
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