HomeLanguage & LinguisticsLanguage AcquisitionWhat is Input Hypothesis (Krashen)?
Language & Linguistics·2 min·Updated Mar 16, 2026

What is Input Hypothesis (Krashen)?

Input Hypothesis

Quick Answer

The Input Hypothesis is a theory by Stephen Krashen that suggests language learners acquire language most effectively when they are exposed to input that is slightly beyond their current level of understanding. This 'i+1' input helps learners to develop their language skills naturally and intuitively.

Overview

The Input Hypothesis explains how people learn languages by focusing on the type of language input they receive. According to Krashen, effective language acquisition occurs when learners are exposed to language that is just a bit more advanced than what they already know, referred to as 'i+1'. This means that if a learner understands most of what they hear or read, they are more likely to pick up new vocabulary and grammar naturally. For example, if a child who speaks basic English listens to a story that includes new words but is still understandable, they can learn those new words in context. This method emphasizes the importance of understanding over memorization and encourages learners to engage with the language in meaningful ways. It matters because it shapes how teachers approach language instruction, focusing on providing rich and comprehensible input rather than just drills or grammar exercises. In the context of language acquisition, the Input Hypothesis highlights the role of exposure and interaction in learning. It suggests that learners should have access to a variety of language inputs, such as books, conversations, and media, that challenge them just enough to promote growth. By doing so, they can develop their language skills more effectively and enjoyably.


Frequently Asked Questions

'i+1' refers to the idea that learners should be exposed to language input that is just slightly above their current level of understanding. This allows them to grasp new concepts while still being able to comprehend the overall message.
Teachers can apply the Input Hypothesis by providing students with reading materials, audio resources, and conversation opportunities that include language elements just beyond their current abilities. This encourages students to engage with the language in a way that promotes natural learning.
While the Input Hypothesis is a valuable approach, it is not the only method for language learning. Different learners may benefit from a variety of strategies, including explicit instruction, practice, and immersion, depending on their individual needs.