Krashen-Long Input Debate

The Krashen-Long debate is the theoretical disagreement that shapes how second-language materials are written. Stephen Krashen and Michael Long agreed comprehensible input is necessary for acquisition; they disagreed sharply on what makes it sufficient. That disagreement maps onto whether a materials writer engineers rich self-contained texts or builds tasks that drive interactive negotiation.

Krashen's Position

Krashen (1985) framed acquisition as a one-way process: learners acquire a language by understanding messages containing structures slightly beyond their current competence, the i + 1 formulation. The hypothesis assigns no causal role to learner production, no necessary role to interaction, and no requirement for explicit attention to form. Comprehensible input delivered in volume with a low affective filter is the only causal variable. The pedagogic corollary: provide volume, ensure comprehensibility, get out of the way. Extensive reading and the early Natural Approach draw on this view.

Long's Position

Long (1981, 1996) accepted the necessity of comprehensible input but rejected the claim that it is sufficient. The interaction hypothesis locates the acquisitional mechanism in the adjustments speakers and learners make when communication threatens to break down. Negotiation of meaning through clarification requests, confirmation checks, and recasts produces interactionally modified input targeting the gaps the learner has revealed. The 1996 update added selective attention as a mediator and absorbed Swain's pushed output argument: learners must be drawn into producing under communicative demand, not merely understanding.

Why It Matters for Materials Writers

A Krashenite writer foregrounds rich comprehensible texts: graded readers calibrated to i + 1, glossed vocabulary, plentiful repetition. The unit of design is the passage.

A Long-influenced writer foregrounds tasks requiring interaction with information distributed across participants; the text serves the task. Information-gap, jigsaw, and problem-solving formats generate the clarification requests and recasts the theory predicts will drive acquisition. The unit of design is the negotiated exchange.

The same disagreement runs through the simplification-versus-elaboration debate, where Long's preference for elaboration over simplification follows from his rejection of input-as-sufficient.

Status of the Debate

Gass and Mackey (2007) treated input, interaction, and output as a single integrated framework rather than competing hypotheses, and contemporary SLA writing largely follows that synthesis. Krashen's strongest claims (the strict acquisition-learning distinction, the irrelevance of output, the unfalsifiability of i + 1) are widely rejected. What survives is the practical insistence on volume of comprehensible input as a precondition, a point Long never disputed.

References

• Gass, S. M., & Mackey, A. (2007). Input, interaction, and output in second language acquisition. In B. VanPatten & J. Williams (Eds.), Theories in second language acquisition: An introduction (pp. 175–199). Mahwah, NJ: Lawrence Erlbaum Associates.
• Krashen, S. D. (1985). The input hypothesis: Issues and implications. London: Longman.
• Long, M. H. (1981). Input, interaction, and second-language acquisition. In H. Winitz (Ed.), Native language and foreign language acquisition. Annals of the New York Academy of Sciences, 379, 259–278.
• Long, M. H. (1996). The role of the linguistic environment in second language acquisition. In W. C. Ritchie & T. K. Bhatia (Eds.), Handbook of second language acquisition (pp. 413–468). New York: Academic Press.