The language window

Here is my latest Mind and Matter column in the Wall Street Journal

There are many mysteries about Ray, the 17-year-old English-speaking "forest boy" who walked into the city hall in Berlin on Sept. 5, claiming to have lived wild in the woods for five years with his father-until his father recently died in a fall. Judging by his rucksack and his speech, he was not a fully feral child, reared by wild animals and unacquainted with language.

Leo Acadio

Among many legends, from Romulus to Mowgli, only one feral child from the woods might be genuine. Victor, the wild boy of Aveyron in France, who was discovered in 1800, was believed at the time by Jean-Marc-Gaspard Itard, the medical student who took him in, to have "lived in an absolute solitude from his fourth or fifth almost to his 12th year." Yet despite Itard's efforts, Victor never learned to speak, and Itard eventually gave up and "abandoned my student to incurable dumbness."

But there are urban equivalents. In 1828, the year Victor died, Kaspar Hauser was found in Nuremberg, Germany. He had apparently lived not in the forest but in a dark room with virtually no human contact for his 16 years. Like Victor, he adjusted to most things, but not to speech. Even after years of coaching, his syntax was "in a state of miserable confusion." The filmmakers François Truffaut and Werner Herzog turned the stories of Victor and Hauser, respectively, into striking fables.

In 1971, a 13-year-old girl named Genie was found in Los Angeles after a childhood of painful deprivation. The daughter of a blind mother and an abusive father, she had been kept in silence in a single room, mostly either tied to a chair or caged. She was deformed, incontinent and mostly mute. Her only words were "stopit" and "nomore." Although she improved rapidly and developed a good vocabulary, elementary grammar and syntax remained beyond her reach.

All of these cases, if they are genuine, reinforce the view that language must be learned within a critical window of time during youth, or it will be too late. Experiments with song birds reach the same conclusion: If deprived of the sound of adult song at a particular age, young finches are never able to learn to sing their species' song. (The research, incidentally, was called the Kaspar Hauser experiments.)

Leo Acadio

A neat, natural test of the critical-window theory is provided by pidgin languages-borrowed vocabularies usually spoken by traders in a foreign land. Pidgins generally lack rules of grammar-inflection at the end of words or schemes of word order. They evolve into creoles, which are grammatical, once they've been learned by children. Children seem capable of imposing grammar on to vocabulary.

In one remarkable case, in Nicaragua in 1979, creating a new school for the deaf led to the development, by the children, of a new sign language. It seems that young brains can do something old brains cannot do, in terms of mastering grammar and syntax. Witness the relative ease with which children learn foreign tongues.

The actual molecular mechanism by which these critical windows or "sensitive periods" of mental plasticity open and close is slowly becoming clear. In mice, lowering the production of the neurotransmitter GABA prevents the start of a sensitive period in which the visual system develops. By contrast, giving the mice benzodiazepines, which mimic GABA, brings on a precociously early sensitive period.

Interestingly, there is evidence that parts of the GABA system are often disturbed in people with autism. But which way: up or down? Autistic children often have high GABA levels, yet the brains of autistic people, postmortem, often have low levels of GABA-making enzymes. Some scientists now think that autism results when a critical window of brain plasticity opens either too early or too late.

These findings are prime evidence of how nature and nurture work together rather than in opposition to each other. The brain is innately designed to be open to experience, but only during a certain period. I like to call it "nature via nurture."