They may have an advantage in that their greater knowledge overcomes the inherent deterioration in their mental agility, but that does not mean that their mind is more adaptable than it was young. As I've said, it's common knowledge that languages are picked up far easier when one is young and the mind is frustratingly stubborn when it comes to learning languages later in life. Yes, there are exceptions--but they are the exceptions, not the rule.



I speak from experience as having immersed myself in Mexico for 10 years and my wife (Mexican) has now been immersed in the U.S. for nearly a year. Yes, you can communicate after a year, but it's a very rare case that one is "fairly fluent" in a year (though that will depend on your definition of "fairly fluent").

And the difference between my Spanish after 10 years in Mexico and a 10-year old Mexican's Spanish is that the 10-year old Mexican is going to have the correct pronunciation and isn't going to make the little grammar mistakes that, while they don't impede communication, they mark the difference between a native speaker and someone that learned it later in life. And it's precisely those "little grammar mistakes" that I'll probably make my whole life regardless of how long I speak Spanish. Why? Because I learned it when I was an adult, not a child. Hopefully with time I'll reduce those errors, but when I have spoken Spanish for 20 years, I'll bet $1k that a 20-year old Mexican speaks it better than I do. :)

Regards,
Craig Steiner