The Subtitle Fallacy -- Why target language subtitles are not your friends
Ok, so in response to various posts and sub-posts on this forum, I decided to do some further experimentation with subtitles and I've come to the conclusion that watching TV shows and movies in your target language, WITH the target languages subtitles, is actually LESS beneficial than watching them with the subtitles in your native language. This may sound counterintuitive to some, but the approach of "real language learners watch with target language subtitles" turns out to be a bit of a fallacy in my opinion. (With some caveats with I'll get into below.) TV shows are not audiobooks and trying to treat them as such doesn't quite work.
What I'm talking about here is casual tv watching in a foreign language as a supplementary activity to your langue studies -- which of course is very beneficial. About 75% of TV I watch nowadays is either dubbed Netflix shows in French and German, or actual foreign shows. I've been doing this mostly with the English subtitles on, but because of the fallacy described above, I switched to target language subs for a while, trying to be a badass. What I've noticed is not only did I understand less of the show but I've spent a hell of a lot more time with my eyes on the target language subs than with the English subs, hindering my listening comprehension in the process.
Three factors play into this, I think:
1.) Professional subs never completely match the spoken lines for various reasons; allotted time, allowed character count, often different translators etc. But that means that if you don't understand a spoken line, you'll often be even more confused by its none matching written companion because your brain is now trying to decipher two foreign language sentences at the same time, leading to many potential overloads.
2.) Reading and comprehending a line of text in your native language is a hell of a lot faster and uses a much smaller fraction of your brain to accomplish. So your attention actually has more bandwidth dedicated to listening to the spoken language when the subs are in your native language.
3.) Because of all that, when the subs are in your native language, it's a lot easier, and more natural to get into a habit of only looking down at the subs when you don't understand something right away -- or when you just need that one unknown word to make sense of something, because your eye can pick apart a written sentence in your own language a lot faster.
Overall, your native subs will teach you more words as well, since they're providing a quick translation to words you may not understand, rather than just providing a written version of an unknown word.
Someone might make the counter-argument that target language subs may force you to eventually read faster in your studied language, but I would argue that that misses the point. Movies and TV shows are an audiovisual medium and are meant to be enjoyed and understood "in the moment," unlike books which are a written medium with no built-in time mechanism or pacing imperative. I think subtitles are there to assist with listening comprehension while keeping you with the pace of the show as much as possible. And for us, the point of watching TV is not to become speed readers, but to increase listening comprehension and ultimately to move away from subtitles at some point and enjoy the show as it was meant to be enjoyed. And for that, it's actually a lot easier to gradually wean yourself off of subtitles by leaving them on native and glancing down less and less as you understand more and more of the spoken language.
When to actually turn off the subs altogether and simulate an "in country" experience is up to the individual, but I'd say I'll turn mine off once I've only looked down once or twice per hour -- something like that. I'd rather have them on and not need them though, somehow that feels more triumphant.
Two exceptions to this: 1.) When only the target language sub is available, such as on the various German TV apps for Das Erste and ZDF, I'll use the German subs on those, because it still helps with clarifying stuff, but I end up doing a lot more pausing and reading. And 2.) If you're actually using the target subs as an active study method, either by themselves or by loading them into LingQ etc. That's a different story of course. (Though I think books are a lot better suited for that sort of thing. Reading is for reading, TV is for watching and listening.)
So, ultimately, I would encourage everyone to free yourselves of "subtitle guilt" and use your native subs as often and as long as you like, and you'll notice needing them less and less.