Every Tuesday, Andy Mayer, 77, leads Hilda Mintzes, 84, and others in a Latin study group. They tackle Ovid's "The Art of Love," translating line by line -- "Your eyes will not be permitted to see her ankles"-- and practice language exercises about Caesar.

What Mayer and his students at the Institute for Learning in Retirement in the District also are doing is smashing stereotypes about language learning and the age at which it is possible to learn. Mintzes loves it: "There is something about the rhythm about Latin that is intellectually stimulating."

In the field of foreign language learning, the mantra has become "the younger the better," with suggestions that anybody older than teen actress Lindsay Lohan should forget about learning another language. Some parents think first grade is too late to start.

That's plain wrong, said linguist Robert M. DeKeyser, and, in fact, some adults can take up a new language -- even those considered extremely difficult, such as Arabic or Japanese -- and become proficient enough to be an FBI translator, if they work at it hard enough.

"Otherwise, we would have to close whole branches of the government," he said.

What a focused adult learning a new language most likely won't be able to do is pass as a native; nobody would mistake the Austrian-born California governor, Arnold Schwarzenegger, for a U.S. native. That talent is probably not important to the majority of language students trying to learn how to, for example, order moules mariniere and a bottle of Bordeaux on Paris's Champs-Elysee.

Though nobody is quite sure how the brain handles language, most linguists agree that children and adults learn and retain second languages differently because the brain changes over time with knowledge and experience.

Children learn inductively, by example and by interacting with the environment around them, and adults tend to learn analytically and deductively, according to former professor Charles Stansfield. His Rockville-based company, Second Language Testing Inc., publishes tests designed to measure foreign language learning aptitude.

Some linguists equate children to "sponges" who soak up all they hear, observations that helped fuel a movement to introduce foreign language early in elementary school.

This also led to the notion of a "critical period" in second language learning, the hypothesis that there is a heightened ability to learn a second language in childhood and that this ability declines sharply at some point, according to Grant Goodall, professor of linguistics at University of California at San Diego and director of its Linguistics Language Program.

Linguists concede that they don't agree on what age that is, but they agree that the critical period often is misunderstood.

For one thing, the critical period generally refers to pronunciation, said Susan Knight, a Spanish professor at Central Michigan University, and not the ability to actually learn another language. (Some experts speak about different critical periods, for other aspects of language learning, such as syntax or grammar.)

Furthermore, some linguists say, the question really is whether the differences between the ways an adult's brain and a child's brain are organized for language learning amount to an adult impairment or simply a different way of learning. Although some adults suffer from memory loss and other debilitating factors, to many linguists, the answer is more commonly the latter.

"You have to teach differently, depending on the age," said DeKeyser, who is joining the University of Maryland at College Park as a professor in the fall and is the incoming editor of the scientific journal "Language Learning."

A child's brain is better able to absorb new sounds. Children also learn better through informal teaching, and adults do better through formal lessons, DeKeyser said. But individual aptitude, methods of teaching and time on task play roles as well.

"It is utterly naive to say the problems are solved just because you start early," he said.

Individual aptitude is little understood by researchers but is important in second language acquisition -- in young people and adults.

Peg Willingham, senior director for public sector development for the International AIDS Vaccine Initiative, took the Modern Language Aptitude Test years ago when she entered the U.S. Foreign Service, and aced it.

She is sure, she said, that her aptitude is "clearly genetic," as she comes from a long line of linguists; her great-grandfather spoke eight languages. She can speak varying degrees of five languages, including Arabic. (She started learning Spanish in eighth grade, French in ninth, German and Russian in college and Arabic as an adult.)

Other people can study Spanish for years and find themselves unable to hold a simple conversation in the language.

"One simple way to think about critical period effects in language is in terms of sports and music," said Robert Kluender, associate professor and chairman of the linguistics department at the University of California at San Diego. "It's very clear that early exposure facilitates the acquisition of the motor and cognitive skills required for high-level performance. Yet we don't all end up as Tiger Woods or Michelle Kwan or the Williams sisters. There, individual variation plays just as big a role."

Another key issue in language learning is time on task. Though adults and children learn differently, both need plenty of time to learn a language, underscoring a key problem with many school programs. Language learning takes hundreds of hours to reach any level of proficiency.

But in many places, children might meet once or twice a week for no more than 45 minutes -- hardly enough time for the implicit learning process at which children excel to work. This helps explain why many people can take years of foreign language classes and wind up not knowing much.

"One week abroad gives more exposure than a whole semester in class in terms of listening comprehension, which I consider the skill least emphasized in many methods but perhaps the most important," said Ron Takalo, associate professor of Spanish at Northwestern College in Iowa.

Mayer once lived in Germany, in fact, and he picked up German by assimilation rather than by formal instruction.

Now, at Temple Baptist Church in Northwest Washington, as part of the institute that is affiliated with American University, he and 68-year-old Ann Peterson and Mintzes enjoy the joys of working with another language.

"People with expansive intellectual interests like to learn new things at any age," Mintzes said.