Who proposed the Input Hypothesis related to second language acquisition?

The Input Hypothesis, which is a significant theory in second language acquisition, was proposed by Stephen Krashen. This hypothesis posits that language learners acquire language most effectively when they are exposed to input that is slightly above their current competence level, a concept referred to as "i+1". This means that learners should understand most of the input but still be challenged with some new elements to promote language acquisition.

Krashen's work emphasizes the importance of comprehensible input, suggesting that language acquisition occurs naturally when learners are exposed to meaningful interactions in the target language. His theories have influenced teaching methodologies in language education, focusing on the necessity for exposure to authentic language use rather than isolated grammar drills.

Other theorists mentioned, such as Lev Vygotsky, Noam Chomsky, and Jean Piaget, have made substantial contributions to education and language development, but they focus on different aspects. Vygotsky is known for his work on social learning and the Zone of Proximal Development, Chomsky is recognized for his theories on innate language structures, and Piaget is renowned for his stages of cognitive development. While these figures have significantly shaped educational theories, they are not associated with the Input Hypothesis specifically.