Krashen's input hypothesis and Monitor Model of second language acquisition

Theory · All theories
Evidence · 14 claims (7 for, 4 mixed, 3 against) · 15 studies (5 causal, 4 quant-synthesis, 3 review, 1 associational, 1 qualitative, 1 theoretical), q1–q3 · 2 of 15 report an effect size · 13 claims rest on one study

Description

The articles present Krashen's theory as five hypotheses. The acquisition-learning hypothesis separates two ways of developing a second language: acquisition, a subconscious process like a child's first-language development, and learning, the explicit presentation of rules with error correction. The natural order hypothesis holds that grammatical structures are acquired in a predictable order. The monitor hypothesis makes acquisition the more important process, since it builds fluency, and gives conscious learning only the job of an editor, or monitor. Adamson's account adds that learned rules can change output only when there is enough time, as on a written test. The input hypothesis holds that learners acquire by understanding input that contains structures "a bit beyond" their current level (i+1). They go "for meaning" first and acquire structure as a result. Speech then emerges by itself after a silent period, and input should come from real communication rather than a grammatical sequence. The affective filter hypothesis holds that anxiety, low self-confidence and low motivation act as a mental block that stops learners from making full use of input.

The articles do not agree on what the monitor allows. Diaz reads the monitor as the heart of the theory and concludes that formal learning "has a role to play" in performance. Calderon's training packet cites Krashen for the view that repetitive drill and a focus on grammar are ineffective. Ponniah (eric-ej1071042) defends the later "Comprehension Hypothesis" as the strongest account in SLA. He reports Krashen's view that negotiating conversations "won't help us to acquire the language", that output and skill-building accounts wrongly make conscious knowledge necessary, and that vocabulary grows by i+1 through reading. The incidental-vocabulary review (eric-ej1051487) likewise cites Krashen (1989) for vocabulary acquired from comprehensible input, but notes researchers who argue that learners must attend to words.

The critiques are sharper than the defences. Adamson argues that the absolute split between conscious and unconscious monitoring is unnatural, and that Labov's continuum of attention fits the variation data better. Nunan's paper (eric-ed367161) quotes Gregg (1986) as the most trenchant, "as yet unanswered" critic of The Input Hypothesis. Ellis (eric-ed338037) reports that the input hypothesis "has not been proven", since no direct test had been run. He also reports that French immersion and intensive communicative programmes supplied plenty of comprehensible input and still produced low grammatical accuracy. Swain's output hypothesis was proposed against that result (eric-ej1095572, eric-ej420159). DeKeyser (eric-ej912917) cites Krashen's claim that "learning does not become acquisition" as part of the case made against practice, and argues for a role for practice.

Implications

Context

• Calderon's packet draws three programme requirements from the hypotheses: provide comprehensible input in the weaker language, maintain subject matter, and maintain the first language.
• Cheung (eric-ed512082) cites Krashen for delaying oral production: early emphasis on speaking takes time away from input, and forcing speech before learners have internalised the rules creates anxiety and errors.
• A monitor needs time to work, so learned rules show most in edited writing and tests, and least in conversation (Adamson).

Target Learners

• Second language learners in general. The articles apply the theory to children in bilingual programmes (Calderon), to L2 writers (Diaz), and to adult ESL and EFL learners (Adamson, Cheung).
• Advanced adult learners are the case the critics raise most often. A diary study of one advanced adult learner (eric-ej420159) and the immersion findings both describe learners who received plenty of input and still did not reach native-like accuracy.

Target Learning Objectives

• Fluent, meaning-focused use of a second language, and vocabulary grown by reading.
• The critiques all concern grammatical accuracy, the objective the input account is said to reach least well.

Claims

• A 1982 bilingual-education teacher-training packet asserts, citing Krashen, that repetitive drill and grammar-focused instruction are ineffective for second language acquisition [+W]
• Monitoring significantly improves a second language learner's accuracy on learnable rules (subject-verb agreement, regular past tense) in the most monitored style [+W]
• Monitoring lowers accuracy for unlearnable rules: preposition usage was significantly less accurate in the more monitored style [~W]
• A 2010 teacher guide reports, citing Postovsky (1974, 1975), that delaying oral production and emphasising aural comprehension early in EFL instruction gives better results than intensive oral practice [+W]
• Comprehensible input alone is insufficient for acquisition of high levels of grammatical proficiency [-M]
• Mere exposure to the target language does not automatically lead to native-like communicative competence in adult learners [-W]
• Participants incidentally acquired an average of 3.19 of 20 target words after reading two passages [+W]
• Implicit learners do not outperform other learners on complex second language rules [-W]
• The probability of learning an unknown word from a single natural-context exposure is roughly .05 to .11, supporting an extrapolated 750 to 5,500 words learned per year from reading [~W]
• Regular past tense accuracy is greatest in planned writing, intermediate in planned speech, and least in unplanned speech [+W]
• L2 learners style-shift in past tense accuracy within narrative discourse according to the amount of planning time available [~W]
• All three input/interaction conditions produced significant gains in vocabulary recognition and acquisition of Japanese locative structures [+W]
• Language proficiency moderates the effect of non-interactive teaching on immediate monitoring accuracy [~W]

The evidence by question

• Is exposure to meaningful input enough for learners to acquire L2 grammar, or do some forms need explicit instruction and practice? Comprehensible input alone is insufficient for acquisition of high levels of grammatical proficiency [-M]
• Do learners acquire second-language vocabulary from reading and other meaning-focused input without deliberate study, and how much? Incidental vocabulary exposure produces reliable learning, but learners pick up only a small share of the unknown words they meet [+S]

Related Theories

• Krashen's five hypotheses of second language acquisition as principles for bilingual program design
• Krashen's Monitor Model: acquisition versus learning as separate internal rule systems
• Krashen's Monitor Model: five hypotheses distinguishing subconscious acquisition from conscious language learning
• Labov's monitor model: monitoring as attention paid to speech form on a continuum — the rival account of monitoring Adamson prefers
• Swain's output hypothesis — proposed against the input hypothesis
• Long's interaction hypothesis — takes the input hypothesis as its first claim
• Schmidt's noticing hypothesis — makes conscious attention a condition of acquisition
• Comparative framework of three SLA theories (Krashen, Complexity, Socio-cognitive) by philosophy and characteristics
• The Comprehension Hypothesis: comprehensible input as the crucial ingredient of second language acquisition
• Interaction hypothesis (Long): negotiation of meaning during interaction generates comprehensible input that drives L2 acquisition
• Larsen-Freeman's tri-part grammatical framework: form, meaning, and pragmatics
• Two-stage model of native language acquisition: natural oral-aural stage followed by nonnatural literacy stage
• Krashen's five hypotheses (acquisition-learning, natural order, monitor, input, affective filter) serve as the principles for second language acquisition in bilingual programs

Examples

• Adjust delivery to students' proficiency so language input is comprehensible during communicative reading activities
• Learning activities have a legitimate place in the language syllabus, but remain secondary to acquisition activities
• Adopting a communicative approach requires teachers to take a dual role facilitating both natural acquisition and learning
• Use process writing techniques in natural language settings to develop the push to communicate and facilitate acquisition
• Sustained Silent Reading — its free voluntary reading variant draws on Krashen

Key Sources

• Krashen, S. D. (1981). Second language acquisition and second language learning. Pergamon.
• Krashen, S. D. (1982). Principles and practice in second language acquisition. Pergamon.
• Krashen, S. D. (1985). The input hypothesis: Issues and implications. Longman.
• Krashen, S. D. (1989). We acquire vocabulary and spelling by reading: Additional evidence for the input hypothesis. The Modern Language Journal, 73(4), 440–464. doi:10.1111/j.1540-4781.1989.tb05325.x
• Gregg, K. R. (1984). Krashen's monitor and Occam's razor. Applied Linguistics, 5(2), 79–100. doi:10.1093/applin/5.2.79
• Gregg, K. R. (1986). [Review of The input hypothesis: Issues and implications, by S. D. Krashen]. TESOL Quarterly, 20(1), 116. doi:10.2307/3586393
• Adamson, D. (1983). Monitoring and the Monitor Model: Labov versus Krashen. WATESOL Working Papers. https://eric.ed.gov/?id=ED242194
• Ellis, R. (1991). The interaction hypothesis: A critical evaluation. ERIC Document ED 338 037. https://eric.ed.gov/?id=ED338037

Page metadata

Field	Value
type	theory
title	Krashen's input hypothesis and Monitor Model of second language acquisition
description	Krashen's account of second language acquisition: subconscious acquisition from comprehensible input a little beyond the learner's current level, with consciously learned rules usable only as a monitor that edits output.
status	review
canonical	True
generated	by claude/unspecified on 2026-09-30
trust	unverified — no one has confirmed this page's content

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