Krashen's Comprehension Hypothesis Model of
L2 learning

Notes by Vivian Cook

Krashen photo

Key Issues in SLA 

Krashen's Five Hypotheses

The Natural Order Hypothesis

'we acquire the rules of language in a predictable order'

The Acquisition/ Learning Hypothesis

'adults have two distinctive ways of developing competences in second languages .. acquisition, that is by using language for real communication ... learning .. "knowing about" language' (Krashen & Terrell 1983)

The Monitor Hypothesis

'conscious learning ... can only be used as a Monitor or an editor' (Krashen & Terrell 1983)

The Input Hypothesis

'humans acquire language in only one way - by understanding messages or by receiving "comprehensible input"'

The Affective Filter Hypothesis

 'a mental block, caused by affective factors ... that prevents input from reaching the language acquisition device' (Krashen, 1985, p.100)




implicit, subconscious

explicit, conscious

informal situations

formal situations

uses grammatical 'feel'

uses grammatical rules

depends on attitude

depends on aptitude

stable order of acquisition

simple to complex order of learning


Combined model of acquisition and production

Krashen Model
Taken from Cook (1993)

Evidence for the Input Hypothesis(chiefly Krashen 1985)

i) people speak to children acquiring their first language in special ways
ii) people speak to L2 learners in special ways
iii) L2 learners often go through an initial Silent Period
iv) the comparative success of younger and older learners reflects provision of comprehensible input
v) the more comprehensible input the greater the L2 proficiency
vi)  lack of comprehensible input delays language acquisition
vii) teaching methods work according to the extent that they use comprehensible input
viii) immersion teaching is successful because it provides comprehensible input
ix) bilingual programs succeed to the extent they provide comprehensible input

Academic reactions to Krashen

Ellis (1990, p.57): 'the lucidity, simplicity, and explanatory power of Krashen's theory'.

Lightbown (1984, p.246): a combination of 'a linguistic theory (through its "natural order" hypothesis), social psychological theory (through its "affective filter" hypothesis), psychological learning theory (through its acquisition-learning hypothesis), discourse analysis and sociolinguistic theory (through both the comprehensible input hypothesis and the "monitor" hypothesis)'.

Mitchell & Myles (1998, p.126): 'The concepts of 'understanding' and 'noticing a gap' are not clearly operationalised, or consistently proposed; it is not clear how the learner's present state of knowledge ('i') is to be characterised, or indeed whether the 'i+1' formulation is intended to apply to all aspects of language, from lexis to phonology and syntax.'

Gregg (1984, p.94): 'each of Krashen's hypotheses is marked by serious flaws: undefinable or ill-defined terms, unmotivated constructs, lack of empirical content and thus of falsifiability, lack of explanatory power'

McLaughlin (1987, p.56): 'Krashen's theory fails at every juncture ... Krashen has not defined his terms with enough precision, the empirical basis of the theory is weak, and the theory is not clear in its predictions)

Ellis (1985, p.266): the Monitor Model 'poses serious theoretical problems regarding the validity of the 'acquisition-learning' distinction, the operation of Monitoring, and the explanation of variability in language-learner language'


The Natural Approach (Krashen & Terrell, 1983; Terrell et al, 1997)


General premises

    1. The goal is 'the ability to communicate with native speakers of the target language'

    2. Comprehension precedes production – the Silent Period

    3. Production 'emerges'

    4. Acquisition activities are central, though some Monitoring may be useful for some people sometimes

    5. Lower the Affective Filter: they won't learn if their affective barrier is too high

(6. Speech emerges in stages. Terrell et al 1997)

(7. Group work encourages speech. Terrell et al 1997)

(8. Speech emergence is characterized by grammatical errors. Terrell et al 1997)


Techniques (all acquisition activities)

a) Affective-Humanistic activities

dialogues – short and useful - 'open' dialogues

  • interviews – pairwork on personal information

  • personal charts and tables

  • preference ranking – opinion polls on favourite activities etc

  • revealing information about yourself – e.g. what I had for breakfast

  • activating the imagination – e.g. give Napoleon advice about his Russian campaign

b) Problem-solving activities

  • task and series – e.g. components of an activity such as washing the car

  • charts, graphs, maps – e.g. busfares, finding the way

  • developing speech for particular occasions – e.g. What do you say if …

  • advertisements

c) Games, e.g. What is strange about … a bird swimming?'

d) Content activities, e.g. academic subject matter such as maths


Some anti-Krashen opinions from California, 
taken from KrashenBurn (see end)

Alice Callaghan (Episcopal priest), ‘...a parasite on the backs of poor Latino children.’

Isaac Cubillos, editor of Latino Beat ‘...more than 2.5-million kids statewide have not made it as a result of bilingual education. What an atrocious situation, and Krashen helped create this."

Isaac Cubillos, editor of Latino Beat, ‘I discovered that Dr. Krashen has done no research. It is purely a theory. There is no test data, there are no schools where it's been proved, and it's based on thin air.’

Christine Rossell "Krashen denied having ever criticized that study. He will say anything to win over a room."

David Tokofsky, "This is how every administrator in the state got promoted from assistant principal to principal, or from teacher to bilingual coordinator, or from regional supe to district supe: By chanting the Mantra of 'Rama, Rama, Krashen, Krashen, Rama, Rama.'

one stunned non-educator in the audience: "An impromptu receiving line formed of teachers lining up for a chance to touch their guru, their Pied Piper. It was eery. It was the Church of Krashen."


Krashen's own website:

References (& see web links below)

Barasch, R.M. & Vaughan-James, C. (eds) (1994), Beyond the Monitor Model, Heinle & Heinle

Gregg, K. (1984), 'Krashen's Monitor and Occam's Razor', Applied Linguistics, 5 (2), 79-100

Krashen, S. (1979), 'The Monitor Model for second language acquisition,' in R. Gingras (ed.) Second Language Acquisition and Foreign Language Teaching, CAL

Krashen, S. (1981), Second Language Acquisition and Second Language Learning,Pergamon

Krashen, S. (1982), Principles and Practice in Second Language Acquisition, Pergamon

Krashen, S. (1985), The Input Hypothesis: Issues and Implications, Longman

Krashen, S. (1985), Language Acquisition and Language Education, Alemany Press

Krashen, S. (1993), The Power of Reading, Libraries Unlimited Inc, Englewood Colorado

Krashen, S. & Biber, D. (1988), On Course: Bilingual Education’s Success in Califormia, California Association for Bilingual Education, Sacramento

Krashen, S. & Terrell, T.D. (1983), The Natural Approach, Pergamon

McLaughlin, B. (1987), Theories of Second-Language Learning, Edward Arnold, London



Acquisition versus Learning Exercise
Ask your partner

1. to describe an L2 (or L1) rule they learnt consciously
2. to say how they used it to start with
3. to say the extent to which they use it now
4. to evaluate how useful they found it
5. to say what they can do in an L2 they did not learn but acquired
6 to remember how they acquired this
7. to say how important they found it

Do you agree with acquisition versus learning

Rate these teaching activities on a scale from 1-10 as involving comprehensible input:

- repetition of sentences in a dialogue
- reading a story aloud followed by questions
- students exchanging their views about their favourite music
- students listening to grammatical explanation
- studying a poem together
- learning lists of vocabulary with their translation
- listening to how an activity should be done and then carrying it out
- acting out going by train


An Italian being interviewed by an English speaker (ESF project) (slightly tidied)

Is Andrea using acquired or learnt knowledge? How can you tell?

I: Had you seen this film before?
Andrea: No never.
I: Have you seen other Charlie Chaplin?
Andrea: Ya [long pause] mm [long pause] its okay.
I: I think so.
Andrea: [laughs] after - Charlie Chaplin er take the coon [/?] cuneos [=T wedge] the piece of wood er.
I: mhm.
Andrea: er under the boat. And the boat go into the sea I don't know.
I: Mhm mhm.
Andrea: Er he has finished - the < > [laughs] the work.
I: Ya.
Andrea: Your your job. Ya?
I: mhm.
Andrea: He working only for I don't know for ten minutes [laughs] and er and he go go outside er this er er cantieres [=T shipyard] ?
I: outside the?
Andrea: cantieres [=T shipyard].
I: canteen?
Andrea: building construction.
I: mhm.
Andrea: of the the boat.
I: outside the docks you mean.
Andrea: the docks.

For a fierce anti-Krashen view see 

(however a video downloader tried to force itself on me from this site so beware)
Some quotes given above. 


Second Language Learning and Language Teaching (book extras)

Vivian Cook on Wikipedia