How is 'input' defined in language acquisition theories?

In language acquisition theories, 'input' is defined as the language that a learner is exposed to and understands. This concept is crucial because it highlights the importance of exposure to language in the process of learning. Input encompasses all forms of language that are accessible to the learner, including written texts, spoken conversations, and other forms of communication, as long as the learner is capable of comprehending them.

Input is foundational in theories such as Stephen Krashen's Input Hypothesis, which suggests that language acquisition occurs most effectively when learners are exposed to language that is slightly above their current level of proficiency, referred to as ‘i+1’. This idea emphasizes that meaningful and comprehensible input is essential for learners to develop their language skills naturally.

The other choices focus on different aspects of language learning. The output produced by the learner pertains to their spoken or written language use, which is different from input. Feedback from teachers represents external assessments of the student’s performance rather than the language exposure necessary for acquisition. Lastly, assessment of language skills is a method of evaluating proficiency rather than a component that influences the acquisition process directly.