Context & Comprehensible Input

If you're unfamiliar with the topics of immersion learning and comprehensible input, I'd recommend watching Stephen Krashen on Language Acquisition and Optimal Input respectively.

In the language learning community there's some disagreement on whether or not input needs to be comprehensible in order to acquire the language. Even among those who think input does need to be comprehensible, there's disagreement about how comprehensible. I think there's an interesting discussion to be had here, and the topic might not be as black-and-white as you might think.

Personally, I believe input must be comprehensible to acquire language (and I'm going to try to convince you of the same). This may be surprising if you've read my other articles, since in the past I've linked an experiment where a linguist learned french with 1300 hours of raw listening; no reading, no subtitles, no output, no grammar. That sure sounds like incomprehensible input. After all, what's more incomprehensible than listening to conversations in a completely foreign language you have 0 experience with?

I'm going to make a fairly bold claim here. I believe almost all input is comprehensible.

Maybe this is going into semantics a bit too much, but I think it's important to define exactly what comprehensible input is. I do not think comprehensible input necessarily means understanding words. Rather, it's about understanding the meaning behind a message. We see this all the time in nonverbal communication. There is meaning behind body language. We can tell if someone wants to get out of a conversation if they start turning their body away. If someone gives you the middle finger, you know what they mean even though they didn't even open their mouths. That's comprehensible input.

So if comprehensible input is about the message, not the words, what criteria are important for determining comprehensibility?


In a sea of unknown words and sounds, the only way you can understand meaning is through context. Language learners typically make the mistake of assuming that context means learning an unknown word because you understand all the words around it. Of course, that is context, but merely one form of it.

Context is any piece of information that assists in understanding something (even if it's very vague). If you're watching TV or reading comics, the imagery is context that can help you understand what's being talked about. If you're listening to something, the tone of voice the speaker uses can give hints on meaning (especicially if someone screams a word as a reaction to something else). Even something as small as punctuation and sentence length can give small amounts of context. Loan words are context, as well as any similarities you may find if you learned a language within the same language family.

If there was a situation that truly had 0 context (incomprehensible input), it would be impossible to learn, because there would be absolutely no way to understand any meaning whatsoever. In practice, this situation pretty much never happens.

Optimal Input

Of course, just because you can learn a language with minimal context (just by spamming enough hours), that might not necessarily be the best use of your time.

In Optimal Input, Stephen Krashen says that optimal input provides a large quantity of rich comprehensible input, that is extremely interesting.

For someone fairly new to the langauge, watching video game livestreams on Youtube may be comprehensible (because of the context you get from the visuals/knowing about the game), and it may also be extremely interesting depending on the person. However, you're not going to get a lot of rich meaningful input from it.

In fact, I think this is a very common mistake for beginners. It makes sense to immerse in things you enjoy, but what if the things you enjoy make for shitty immersion (personally I think raw listening is shitty immersion, especially for beginners). In my article What Makes Immersion Meaningful (And Why Passive Immersion Isn’t a Thing), I discussed the importance of focus and intensity in immersion.

If your immersion material lends itself to being low-focus (easy to doze off while listening to something), or is low-intensity (this could be low volume of vocabulary, or just content you don't have to strongly engage with to consume), your progress will be miles behind someone who put in similar hours doing something more effective.

Personally, I've found a couple more criteria that I think are necessary for input to be optimal.

  1. Input should be primarily text-based. This means you're going to have to read. A lot. This doesn't necessarily mean you have to jump directly into raw novels day 1 (although you can if you want). Subtitled video, or audio with a transcript also work just fine (although video will probably be more effective in the beginning because of visual context).
  2. Input should be enjoyable. This is a repeat of what Krashen said, but I think it's worth reiterating. The people who succeed the quickest are people who genuinely enjoy the immersion they're doing, to the point of near obsession. Like when you find a book that's so good you can't put it down, if input is enjoyable enough, you'll naturally put in the hours needed for fluency without it feeling like a chore.
  3. Zero whitenoising. While it's important to get used to not fully understanding the meaning of things you read, it is utterly ineffective to immerse without looking anything up. After all, a definition gives far more context than subtle gestures or tones. Immersing without looking things up is like listening to/watching white noise. Instead, you should make it a point to look up everything you don't understand (as much as possible, but not up to the point where you get a headache and want to quit).
  4. In the same vein as the last point, you should have a setup that makes looking things up as quick and seamless as possible. I cannot overstate the importance of a really good immersion setup. I personally recommend Yomichan & Animebook for watching video (you can use youtube-dlp to download youtube videos with subtitles for use with animebook if you want), and ttu-reader with Yomichan for reading. Honestly the point in common is Yomichan, just use it absolutely everywhere, as much as possible.

If you look at highly successful Japanese learners such as Stevijs, Doth, or Jazzy, all of them achieved it by putting in a huge number of hours of reading, and they started reading far before most people would consider themselves "ready" to start reading.

Anyways, what I'm trying to say is, optimal input is reading. You can kind of ignore the rest of the article, just go read.