Which famous language acquisition expert developed the input hypothesis or monitor model?

• A. Noam Chomsky
• B. B.F. Skinner
• C. Lev Vygotsky
• D. Stephen Krashen

Answer: (D)

The concept being tested is identifying who developed Krashen’s input hypothesis and monitor model in second language acquisition. Stephen Krashen argued that language grows most from comprehensible input—language that learners can understand but that is slightly beyond their current ability (often described as i+1). This idea emphasizes understanding meaning in real communication rather than focusing on explicit grammar drills. The monitor model expands on this by describing how acquisition and learning work together: acquisition is natural, fluency-building knowledge, while learning is conscious knowledge of rules that can act as a monitor to correct or edit what we produce when conditions allow. It also includes the idea that input, together with affective factors like motivation and anxiety, shapes progress and that there’s a natural order to the ease with which different forms are acquired.

Contextually, these ideas contrast with other famous theories: Noam Chomsky is associated with the idea of an innate language faculty and Universal Grammar, B.F. Skinner with behaviorist explanations that emphasize language through conditioning and habit formation, and Lev Vygotsky with social interaction and the zone of proximal development as central to learning. Recognizing Krashen’s namesakes—the input hypothesis and monitor model—helps you identify him as the developer of these particular concepts.