The science of turning words you know into words you use

You understand far more words than you use. Linguists call this the gap between receptive and productive vocabulary: words you recognize on the page but never produce yourself. In learners tracked over time, the receptive side grew much faster, and the gap widened as they advanced.^1,2 Everything in Reach exists to move words across that gap. Each piece of the app comes from a specific finding about how memory works.

When you capture a word, Reach saves the sentence you found it in and shows it back to you when you practice. Memory research calls this encoding specificity: you recall something best with the cues present when you learned it.³ It also mirrors how vocabulary grows in the first place; much of it is picked up incidentally from context while reading, not from lists.⁴ A word on its own is a flashcard. A word with its sentence is a memory with a hook.

A dictionary entry hands you every sense of a word at once. Reach does the opposite: it confirms the single sense you met, in the context you met it, and trains that one. The caution comes from interference research; students who studied sets of similar words together mixed them up and learned each one more slowly.⁵

Rereading a definition feels like learning, but the feeling misleads. In a classic experiment, students who repeatedly recalled foreign vocabulary remembered about 80 percent of it a week later; students who kept restudying without being tested remembered about a third.⁶ And generating a word yourself, rather than reading it, strengthens memory on its own, a result known as the generation effect.⁷ Writing a sentence asks for both at once: you retrieve the word and you produce with it. That is why a word graduates in Reach only when it shows up in your own writing, not when you have seen its definition enough times.

Memory fades on a curve, steep at first and flatter with every successful recall; Ebbinghaus charted it in 1885 and it has held up since.⁸ Reviews spaced out over time beat the same reviews crammed together, one of the most replicated results in learning research.⁹ Reach spaces each word's reviews at growing intervals: a day, then two, then four, then a week. A hint or a miss brings the next review sooner. Every recall lands after a real delay, and effortful recalls are the ones that flatten the curve.

1. 1. Laufer, B. (1998). The development of passive and active vocabulary in a second language: Same or different? Applied Linguistics, 19(2). doi:10.1093/applin/19.2.255 ↩
2. 2. Nation, I. S. P. (2001). Learning Vocabulary in Another Language. Cambridge University Press. doi:10.1017/CBO9781139524759 ↩
3. 3. Tulving, E., & Thomson, D. M. (1973). Encoding specificity and retrieval processes in episodic memory. Psychological Review, 80(5). doi:10.1037/h0020071 ↩
4. 4. Nagy, W. E., Herman, P. A., & Anderson, R. C. (1985). Learning words from context. Reading Research Quarterly, 20(2). doi:10.2307/747758 ↩
5. 5. Tinkham, T. (1993). The effect of semantic clustering on the learning of second language vocabulary. System, 21(3). doi:10.1016/0346-251X(93)90027-E ↩
6. 6. Karpicke, J. D., & Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319(5865). doi:10.1126/science.1152408 ↩
7. 7. Slamecka, N. J., & Graf, P. (1978). The generation effect: Delineation of a phenomenon. Journal of Experimental Psychology: Human Learning and Memory, 4(6). doi:10.1037/0278-7393.4.6.592 ↩
8. 8. Ebbinghaus, H. (1885). Über das Gedächtnis. Published in English as Memory: A Contribution to Experimental Psychology (full text). ↩
9. 9. Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T., & Rohrer, D. (2006). Distributed practice in verbal recall tasks: A review and quantitative synthesis. Psychological Bulletin, 132(3). doi:10.1037/0033-2909.132.3.354 ↩