L3 is easier, but is it quicker?

[lusan]

your age (controversial)

Well, I'm on the side of this controversy that says that one's ability to learn declines continuously from birth till death. Don't hurt me folks, we all have opinions. This isn't even a political one.

But yeah, I think that applies to learning musical instruments, etc., not just languages. I vaguely recall reading that a bird that's never flown as a chick will never learn to fly as an adult. The critical period has passed, the brain's plasticity went down.

It takes years to really master a language. If you're doing them sequentially, by the time you get to the next one your brain's plasticity has declined substantially. All else equal, it will be harder than last time.

Will it be easier for you to learn L3 at 35 than for a different person to learn L2 at 35? Let's say that you're both learning languages that have no relationship to those you already speak. My intuition tells me that it will be a little easier for the already bilingual person. But I'm less confident about that than about the age effect.

Maybe... I am 65 year old. I took French seriously, 2 years ago and I can manage well. I guess it depends of our native language. My first language is Spanish and my second English... so I suppose I get some help from them. Polish has been a difficult battle done only because my wife is Polish. Otherwise... I would not take that journey.

[leosmith]

does this mean merely that it feels like less of an effort, or does it also take less time to reach a given level of fluency (all else being equal)?

As others have said, the thing that makes you faster is learning what works for you and modifying your method to become more efficient. So I was about to answer "yes". But then I thought, wait a second "all else being equal" means you don't modify your method, so my answer is "no".

Of course, there is no such thing as "all else being equal" in language learning, and in addition to other obvious important stuff that could be unequal like motivation, I doubt anyone could cast aside improvements to their techniques just to keep things equal. So I officially change my answer to "maybe".

I'm on the side of this controversy that says that one's ability to learn declines continuously from birth

you get better at learning

I'm glad we are all in agreement. Maybe it is!

[Dragon27]

But yeah, I think that applies to learning musical instruments, etc., not just languages. I vaguely recall reading that a bird that's never flown as a chick will never learn to fly as an adult. The critical period has passed, the brain's plasticity went down.

That's a shaky analogy. A bird that has never learned to fly can be compared to a feral child that has never learned a human language, but not to a normally developed human who has learned at least one (their native) language.

[El Forastero]

The problem of this question is what exactly you are comparing?

If the question is: "is your L3 quicker than your L2", the answer could be "Who knows!". There are several variables involved as people have already discussed. In my case, my L6 has been by far the slowest if the languages I have ever studied and my L5 has been the quickest so far. L6: Russian, L5: Italian

If the question is "Would your L3 be quicker to learn if it were your L2?", the answer is definitely yes.

[kelvin921019]

Depends. The speed of acquisition depends on a lot of factors and experience is only part of it.
Nevertheless, when you have the experience of going through a L2 from 0 to automatic (B2 or above), you will know what to expect ahead in your L3 journey and perhaps even what to do. It at least eliminates your fear of not getting anywhere and keeps you going.