2.2 Krashen's Monitor Model & the Communicative Hypothesis
Key Takeaways
Krashen's Monitor Model posits that subconscious acquisition—not conscious learning—is the primary driver of spontaneous second language fluency.
The Monitor hypothesis specifies that conscious knowledge functions only as an internal editor under three strict conditions: sufficient time, focus on form, and explicit rule knowledge.
Comprehensible input at the i+1 level drives acquisition, provided the learner's affective filter is sufficiently low to allow input to reach the Language Acquisition Device.
Modern SLA researchers refined Krashen's framework by demonstrating that pushed output (Swain), interactional negotiation (Long), and conscious noticing (Schmidt) are also essential for linguistic accuracy.
Overview of the Monitor Model
In the late 1970s and early 1980s, Stephen Krashen formulated the Monitor Model (the Input Hypothesis framework), providing theoretical groundwork for Communicative Language Teaching (CLT) and the Natural Approach (co-developed with Tracy Terrell, 1983). Krashen posited that adult learners develop second language competence through two distinct systems: an acquired system and a learned system. The model consists of five interrelated hypotheses prioritizing comprehensible, meaning-focused input over explicit grammar drill.
The Five Core Hypotheses
1. The Acquisition-Learning Hypothesis
Krashen established a fundamental distinction between two independent processes:
- Acquisition: A subconscious, intuitive process identical to child first language development. It occurs naturally when learners focus on message comprehension in meaningful communication. Acquired knowledge is stored implicitly, generates an intuitive "feel for correctness," and initiates spontaneous fluent speech.
- Learning: A conscious, analytical process involving explicit grammar study, rule memorization, and metalinguistic awareness ("knowing about" language). Learned knowledge is stored explicitly as conscious rules.
Krashen asserted the non-interface position: learned knowledge cannot convert into acquired competence. Memorizing grammar rules does not yield automated communicative fluency. While debated by cognitive linguists, this hypothesis redirected classroom priorities from grammatical drills toward authentic, meaning-centered interaction.
2. The Monitor Hypothesis
The Monitor Hypothesis defines the restricted operational role of conscious learning. Speech production is initiated entirely by the acquired system; conscious learning serves solely as an internal Monitor (editor) that inspects and edits utterances before or after production.
Using the Monitor requires satisfying three strict conditions simultaneously:
- Sufficient Time: The speaker must have adequate cognitive processing time to retrieve conscious rules without interrupting communication.
- Focus on Form: The speaker must focus intentionally on grammatical correctness rather than communicative meaning.
- Knowledge of the Rule: The speaker must possess an accurate mental representation of the rule.
Krashen categorized three Monitor user profiles:
- Monitor Over-Users: Learners who constantly reference rules, resulting in hesitant, halting speech and severe fluency inhibition due to anxiety over errors.
- Monitor Under-Users: Learners who rely solely on acquired intuition, ignoring formal rules and error correction; they prioritize speed over accuracy.
- Optimal Monitor Users: Learners who employ the Monitor judiciously during planned speech or writing without disrupting communicative flow.
3. The Natural Order Hypothesis
Supported by morpheme acquisition studies (Dulay, Burt, and Brown), the Natural Order Hypothesis asserts that grammatical structures are acquired in an invariant developmental sequence regardless of native language or instructional sequencing:
- Early Acquired: Present progressive (-ing), plural (-s), and copula be.
- Next: Auxiliary be (is walking) and articles (a/the), followed by irregular past-tense forms (went).
- Late Acquired: Regular past (-ed), third-person singular present (-s), and possessive ('s).
Instruction cannot alter this developmental order. Teaching late-acquired morphemes early does not accelerate acquisition; learners only internalize structures when developmentally primed.
4. The Input Hypothesis
The Input Hypothesis explains the mechanism of acquisition: humans acquire language exclusively by receiving comprehensible input containing structures slightly ahead of their current developmental stage.
This is formalized as:
Where represents current acquired competence, and represents the next developmental structure. Input becomes comprehensible through context, gestures, visuals, and prior knowledge.
Key corollaries include:
- The Silent Period: A natural receptive stage where beginners process input before speaking; speech should not be prematurely forced.
- Speech Emergence: Spoken fluency emerges organically from comprehensible input; it cannot be taught directly via drills.
5. The Affective Filter Hypothesis
The Affective Filter Hypothesis explains individual acquisition differences under similar input conditions. The Affective Filter acts as an internal psychological screen regulating input flow to the Language Acquisition Device (LAD):
- Anxiety: Debilitating classroom anxiety raises the filter, blocking input. Low anxiety keeps the filter permeable.
- Motivation: High communicative and integrative motivation lowers the filter.
- Self-Confidence: Strong self-esteem fosters a low filter, facilitating intake.
When the filter is high, the learner is defensive and input is deflected. When the filter is low, input penetrates freely, reaching the LAD to become intake.
Note
The language instructor's dual mandate is providing rich comprehensible input () while lowering the affective filter through an encouraging, low-anxiety classroom climate.
Modern Refinements and Counter-Theories
While Krashen elevated communicative input, contemporary SLA researchers established that input alone is insufficient for complete grammatical accuracy.
Swain's Output Hypothesis
In Canadian French immersion studies, Merrill Swain (1985) found that students receiving extensive comprehensible input developed receptive comprehension but lagged in grammatical precision. Swain's Output Hypothesis (output that pushes learners beyond their current resources; the functions are set out in Swain, 1995) identifies three functions:
- Noticing Function: Producing language reveals gaps between learner intent and linguistic resources, directing attention to relevant input.
- Hypothesis-Testing Function: Learners test tentative linguistic structures against interlocutor feedback.
- Metalinguistic (Reflective) Function: Learners use language to talk and think about language itself, as when pairs debate which form is correct during collaborative writing.
Across these functions, Swain argued that producing language pushes learners from semantic processing (understanding the gist) toward syntactic processing (building the grammatical form).
Long's Interaction Hypothesis
Michael Long (1983, 1996) demonstrated that input is made comprehensible through negotiation of meaning during communication breakdowns. Through modifications—clarification requests, confirmation checks, and recasts—learners connect input, internal processing, and output dynamically.
Schmidt's Noticing Hypothesis
Richard Schmidt (1990) refuted the claim of entirely subconscious acquisition, demonstrating that conscious noticing of surface linguistic forms is necessary to convert input into intake. Unnoticed features do not penetrate developing interlanguage systems.
Krashen's Hypotheses and Modern Refinements Matrix
| Construct | Proponent | Core Proposition | Classroom Mechanism | Pedagogical Implication |
|---|---|---|---|---|
| Acquisition-Learning | S. Krashen | Subconscious acquisition drives fluency; conscious learning yields metalinguistic facts | Meaningful communicative interaction | Prioritize meaningful interaction over mechanical drills |
| Monitor Hypothesis | S. Krashen | Conscious rules edit output when time, focus, and rule knowledge coincide | Writing editing, prepared presentations | Train optimal monitor use without sacrificing fluency |
| Natural Order | S. Krashen | Morphemes follow an invariant developmental sequence | Natural language exposure in context | Do not expect immediate mastery of developmentally late forms |
| Input () | S. Krashen | Comprehensible input slightly beyond current level drives acquisition | Visuals, realia, gestures, context | Provide multimodal input; respect the silent period |
| Affective Filter | S. Krashen | Emotional factors (anxiety, motivation, confidence) gate input to LAD | Safe, collaborative atmosphere | Lower anxiety to convert input into intake |
| Pushed Output | M. Swain | Output forces transition from semantic decoding to syntactic encoding | Collaborative tasks, guided writing | Require active production to notice gaps and test hypotheses |
| Interaction | M. Long | Meaning negotiation during breakdowns maximizes input comprehension | Information-gap tasks, recasts | Structure tasks requiring reciprocal information exchange |
| Noticing | R. Schmidt | Conscious awareness of form converts input to intake | Textual enhancement, guided discovery | Draw deliberate attention to target linguistic forms |
Tip
Exemplary communicative teaching integrates both models: delivering comprehensible input () in a low-filter setting while facilitating interactive negotiation (Long), conscious noticing (Schmidt), and pushed output (Swain).
A high-intermediate adult learner speaks English with significant hesitation, pausing repeatedly before every sentence to mentally rehearse grammatical verb endings and word order. Although the learner scores high on written syntax examinations, their conversational fluency is severely impeded. How would Krashen's Monitor Model classify this student, and what instructional adjustment is most warranted?
Monitor Under-User; the teacher should introduce rigorous structural substitution drills to enforce rule automaticity.
Optimal Monitor User; the teacher should assign more analytical writing tasks to exploit their strong grammatical competence.
Monitor Over-User; the teacher should add low-stakes fluency tasks that put the message before formal precision.
Affective Filter Rejector; the teacher should administer standardized diagnostic tests to identify cognitive processing deficits.
Which empirical finding from Canadian French immersion programs led Merrill Swain to propose the Output Hypothesis as a necessary refinement to Krashen's Input Hypothesis?
Learners required native-language translation to successfully lower their affective filters before reading authentic texts.
Learners completely bypassed the natural acquisition sequence when provided with explicit metalinguistic explanations.
Learners reached strong listening and reading comprehension but lagged in grammatical accuracy when speaking and writing.
Learners who were exposed to comprehensible input suffered from severe communicative anxiety during informal peer discussions.
An ESL curriculum is designed so that the third-person singular present-tense marker '-s' (e.g., 'she walks') is explicitly taught and tested in Week 1 of a beginner course. Despite repeated drills, students consistently omit the '-s' in spontaneous conversation until months later. According to Krashen's Natural Order Hypothesis and subsequent morpheme studies, what explains this outcome?
The teacher failed to enforce Swain's pushed output protocol during the initial introductory presentation.
The audiolingual habit formation process was corrupted by negative native-language phonological transfer.
The students have raised affective filters that permanently block the acquisition of morphological inflections.
Third-person -s is acquired late in the natural order, and syllabus sequencing cannot force it earlier.
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