March 4, 2007
The New York Times

Any adult who sets out to learn a foreign language knows how frustrating it can be to make sense of the simplest rules of semantics and syntax. Words are hard to remember; phrases, hard to come by. The mere task of pronunciation can be a battle for control: your brain tells your tongue to vibrate against the roof of your mouth, but your tongue rolls on itself instead.

As more immigrants enroll in publicly financed English classes, they are discovering that the frustrations of long waiting lists, crowded classrooms and missing textbooks are often dwarfed by the challenge of learning the language of their new home.

“I think this is one of the most difficult things I’ve ever done,” Maria de Oliveira, 26, an immigrant from Brazil, said in her native Portuguese. She lives in Yonkers and has been taking English classes since mid-January.

The fact is, it is hard for adults to learn a new language, much harder than it is for their children. But there is no simple answer as to why that is the case.

In 1959, the neurosurgeons Wilder Penfield and Lamar Roberts tried to answer the question. They concluded that there was a critical period, ending around puberty, when the brain, with proper stimuli, is best suited to learn a language. After that, the task becomes much more difficult.

Their theory remains controversial, and neuroscientists and linguists have broadened the inquiry. They say social and psychological factors also are at play.

Children who must learn a new language have certain advantages over adults beyond biology, researchers say, starting with the fact that they are not preoccupied with paying the bills or figuring out what’s for dinner. Their minds are clear and relaxed.

By contrast, said D. Bradford Marshall, an expert in language acquisition at Harvard, “adult immigrants are thrust into a society they don’t understand, which only compounds their anxiety.”

To succeed, he said, adults must have self-confidence, a strong desire to learn and a willingness to stick with it.

Another advantage immigrant children enjoy is that they are often surrounded by native speakers, in schools or on playgrounds, while adults tend to gravitate toward people who speak the same language as they do. That safety net becomes their greatest barrier to full exposure to the language of their new country, according to Dr. Michael Merzenich, professor of neuroscience at University of California, San Francisco.

Dr. Merzenich has also theorized that the brains of people who speak but one language become progressively preoccupied with that language as they grow older, making it harder for them to absorb a new language.