- To read without a dictionary, you need to know about 98% of the words on the page.
- So NativeLingo aims for 1 swap per 100 words, and never goes past 2.
- Seeing a word isn't the same as remembering it. A short typed review covers the gap.
The 98% line
Hu and Nation (2000) gave readers the same short story with different shares of unfamiliar words. Understanding held up near the top and fell apart quickly as unknown words piled up. Their estimate, repeated by Nation in 2006: comfortable reading takes about 98% known words.
Two unknown words in a hundred is already the edge. That's roughly one per paragraph. Here's what the difference looks like:
Why not more?
Early versions of NativeLingo swapped far more, up to one word in five. It looks great in a screenshot. On a real page you stop reading and start decoding, and a week later the extension is off.
So the limits live in the extension itself, not in a setting you can crank up:
Seeing isn't knowing
Pellicer-Sánchez and Schmitt (2010) followed words through a novel. After ten or more meetings, 84% of readers recognised a word's meaning. Only 55% could recall it on their own.
After 10+ encounters in a novel. Pellicer-Sánchez & Schmitt, 2010.
That gap is why there's a review. Karpicke and Roediger (2008) found that once you've recalled something, rereading it adds almost nothing a week later, while testing yourself keeps about 80%. So the review asks you to type the word instead of tapping “I knew it”.
The page shows you the word. The review is where you learn it.
What to expect
Two or three highlighted words in a long article. None on some short pages. That's normal.
Pick a daily goal you can keep. Five new words a day turns into 7–10 minutes of review a day after a year. Twenty turns into 30–40. Most people should start with five.