I don't know of any research that specifically measures the progress of learning 2+ languages at the same time vs learning one language, then another. Meaning, given some fixed amount of time, perhaps 24 months, group A learns two languages at the same time for all 24 months and group B learns one language for 12 then another for 12.

The problem with designing a research study around this is the "forgetting curve". If you learn one language and then <em>do nothing with it for a year</em>, it's probably going be <em>very rusty</em> compared to someone who has had less intense exposure but for all 24 months.

Similarly, if you study for 2 hours on one day versus 30 minutes on 4 days, I expect you will remember more. Current research on memory supports spaced repetition and "forget-then-remember". In the book <em>Fluent Forever</em>, there is some explanation for why. Sleep also seems to really help people remember - it's like the mind reorganizes while the person rests.

If I had to guess, I would say that there is a sort of "minimum viable time" that must be spent with each language. Children can learn many languages simultaneously, but they must receive a number of hours each week in each or else they just never seem to get much more than a passive understanding. Practically speaking, four languages seems to be the upper limit for them; after that, you have to create a lot of artificial situations to maintain needed exposure.

So Ahmad, if you want to learn multiple languages, I would say that you should make sure you have sufficient time to spend to each in order to sure you make enough progress. If you can't get past the "forgetting curve", then your limited time would be better spent focusing on one, and not on focusing on two and making no progress on one or both.

I don't really get your question. .do you want to know what kind of difficulties could appear or what we think about it in general? If it's tiring?...

So i will just write my experiences with learning more than one language:

I'm currently learning Latin, Spanish, English and French in my school and Korean alone at home and sometimes i have problems with setting priorities (for example: on which language should i focuse the most? Which one is more important? ...). Now and then i also mix the Latin based languages (mainly French and Spanish).

I think learning two languages at the same time would be easier if it's a romance language and another language that's not a romance language..for example german and spanish or chinese and french.

Ps.: sorry for my spelling mistakes and missing punctuation..I'm typing this on my mobile phone. :) and I'm also apologising in advance if the things i typed don't make sense..it's late in my country right now ^^

It is very common. You can learn two or more languages at the same time. But you must absolutely prioritize.

I think it's possible.

Respect -Give2Get-

yes lina,what I want to know that may be focusing on one language maybe make learning easier or faster to be fluency, and thank you for sharing your experience.

and thanks for others