Why Adults Learning a Second Language Often Fall Native-Like Proficiency?

The researchers from the University of Edinburgh, UK explained:

“Words are often described as the basic building blocks of language, however, there is growing evidence that multiword sequences also play an integral role in language learning and processing.”

“When children learn the language, they build on linguistic units of varying size, including multi-word sentences, and not just single words as we often assume.”

“This may explain why adults learning a second language, who tend to rely on individual words, often fall short of reaching native-like proficiency in the way they string words together into phrases and sentences.”

To learn more check the link to "‘Clap your hands" or "take your hands"? One-year-olds distinguish between frequent and infrequent multiword phrases":

https://www.sciencedirect.com/science/article/pii/S0010027721000317