Post here: scientific studies/papers/articles on learning multiple languages at once

I am well aware of the fact that this topic has already been covered. However, as most entries were based on opinions and anecdotal evidence, I’d suggest that we could share the latest research on this relatively young field.

I’d like to start with one study that you can read here:
Take my summary with caution because I did not fully read it after I had already read a summary of it before taking a look at the study itself.
That said, what it seems to conclude is that, while the learning of two languages simultaneously (Russian and English for Chinese students) has no negative side effects on either language, the students learning two languages still had to put more effort into the learning process.
I do hope that there are studies comparing groups of people where one group X dedicates less time to language A than group Y while also learning language B. With that, more interesting synergetic effects might be investigated.

The “International Journal of Multilingualism” (where this study is from) looks like a good place to start the search for more studies on this specific topic.

That aside, please share any other information you can find on that topic.

I am looking forward to discussing some results with you!


Thanks for bringing this up. I am currently trying to learn German (I’m around CEFR B1) and Spanish (I’m around CEFR A2), but I’m finding it hard to focus on Spanish because my German is so much better, so reading and listening to German feels so much more rewarding, because I’m understanding so much more and spending far less time stopping to mark words.

I’m considering giving up one or the other temporarily, but I don’t want it to be Spanish, because that’s the language I’m more likely to use sooner (I plan on visiting Puerto Rico next year). On the other hand, I don’t want it to be German because I feel I’m finally making fast progress. It’s a bit of a dilemma. I guess maybe I should limit my time spent with German, but I worry my motivation will fall off a cliff.

Anyway, I’ll be interested to see any data that this thread brings up, as it will help with my decision.

1 Like

My main second language is French and my comprehension is pretty good. I am also learning German from scratch and I am A2. I spend more time on French. The idea with German is that the learning of a language requires huge spadework, especially at the start, and getting a foundation is tedious. So I’m doing 45-60 minutes a day of German to lay down that boring base, and hopefully master the case system and the basics of prepositions. I find German very hard, prepositions are illogical (to me), and words are often hard to learn. The best place to start is the beginning, and the best time to start is now. However, with time familiarity breeds content, and some of what seemed impossible in German is now not so hard.

1 Like

I am in the exact same place as you, but my main target language is German and my other target language is Spanish.

Other than a month or so on Duolingo, I have never put any effort into learning German grammar. I am at a strong B1 on the CEFR scale and (thanks to spending three months in Germany in 1984) I’ve been speaking German for 30 years. Despite the fact that I know virtually no German grammar (except what I’ve picked up naturally through hearing it used), no German speaker has ever misunderstood me because of my poor grammar. What they’re hearing might sound bad, but my attitude is that if they understand it and we can converse, that’s good enough for me.

If your goal is not merely to understand and be understood, but also to speak German well (for example if you want to use German professionally), then by all means study the grammar. But I’ve heard German grammar is really difficult, and I feel strongly that, if your goal is merely to be understood in German, focused grammar study is unnecessary. Eventually, if you keep getting input in German, you will naturally pick up how to use grammar, simply because you will have seen and heard it used correctly so much that you’ll naturally start speaking that way. I’m living proof that, if all you want is to understand and be understood, the grammar is unnecessary.

1 Like

Skimmed through that study and it seems to compare students with same input of the L2. In that case I wouldn’t think there are differences if L3 studies aren’t so heavy that it would overwhelm. To me language learning loosely compares to playing a game through; you have to go through levels in order and you will finish the game depending how many hours you put in it. If you play a lot, you might finish faster, but maybe not as efficiently. If you play little, you will forget some things along the way. If you play 2 games at the same time it will take more playing time in total, but maybe it doesn’t affect the playing time it takes to finish one of them compared to if you played the same game without playing other game at the same time. Unless the games are similar and you get confused. Hopefully the analogue is as clear as it’s in my mind. So in theory if you have sufficent time to spent in 2 or more langueges to make significant progress and no set goal (like trip to country where language is spoken) when you would like to have one of them at certain level. I decided to start (my L3) by “playing” one at a time to get as much progress as possible in a short period to have a comparison where to draw motivation from. After I get L3 high enough that I don’t need to progress to motivate, I’ll start to dabble with L4.


I don’t doubt your comments on German, I’m but a newbie.

My naive view, for right or for wrong, is that German grammar is doable. I’m slowly getting used to case endings, and my feeling is that it’s not that hard but it will take time. They only have four cases, and they are very meaningful, none of that ergotive, vocative etc. It is often said that German is hard at first, then it gets easier.


While I agree with the game analogy with respect to the time and completion aspect, I have to disagree with the idea of playing two games at the same time as being the same as learning two languages at the same time. Let me elaborate. Based on my personal experience, I would argue for synergetic effects when playing similar games, e.g., shooters. Sure, there might be confusion, but the overall concepts like aim, movement, and so forth are similar. I am also quite sure (when I have time, I will look for studies to back up this claim) that this has already been investigated. That is, when playing two games at once, one might “save” time due to one game making you better at the other. Of course, the question now might be like this: would one have reached the same level in game X had he spent all the time he spent on game Y also on game X? It’s basically a reformulation of the question underlying this thread, but I feel like in the case of video games, there might be a tendency towards both feeding on each other.

1 Like

This is off my memory and rather anecdotal, so take it with a grain of salt: after reaching a level that is about B2 you’ll probably be able to “retrieve” the language even after years of no practise. To get the message straight, stick to a language if you’re likely to reach that point in the near future, even if there is a high chance of you interrupting your language journey soon after.

1 Like

Well, doesn’t same apply to languages? Related languages also help, at least initially. At the end of the day, this was just an analogue and analogues aren’t supposed to be anylized to detail. It’s just a framework the give an overview. Although there is help/hinderance at one point doesn’t mean that it would be that significant over the whole process. The way I see it learaning language is a marathon that really never ends so any initial help/hinderance will be fairly insignificant. Same applies to anything when you try to get closer to perfection. Could have used sports or playing an instrument as an analogue as well. The main point I was trying to bring across, is that it’s mostly about time invested. If you are studying 1h a day and can’t spare any more time, then using 1 hour to study 2 languages almost certainly will slow down our process. If, on the other hand, you have time to spare another 1h to study second language, then it probably wont affect the speed of the first. Unless you think it from the point of few that you could also invest those 2h to that first language. It all depends what kind of targets you have.