The Science of Language Learning: What Research Actually Says

The Science of Language Learning: What Research Actually Says Language learning advice is everywhere. Most of it is based on anecdote, marketing, or the experience of unusually gifted polyglots. The scientific literature tells a more nuanced — and more actionable — story. Here's what decades of second language acquisition (SLA) research actually establishes, with the practical implications for how you should build your study routine. 1. Input Hypothesis: Comprehensible Input Is the Core Driver Stephen Krashen's Input Hypothesis (1982) remains the most influential and most contested theory in SLA. The central claim: language acquisition happens when you encounter input that is slightly above your current level of competence (i+1 in his notation — "comprehensible input"). What the evidence actually supports: High-quality input (reading, listening to native material) is necessary for acquisition Grammar instruction alone without input exposure produces test-takers, not speakers Output (sp