Why Is It Easier for Young Children to Learn a New Language?
One of the most famous discoveries in biology in the last 50 years is that the brains of all young animals go through critical periods when they are particularly receptive to learning.
Tuesday, August 21, 2007
Enjoying the Sunny Side of the Street
Seniors tend to emphasize the positive more than younger people do, and for good reason. As people age, they gain not only life experience but better emotional balance.
Music: It's Play Time!
The ways to get involved making music are as varied as the instruments in a symphony orchestra.
One of the most famous discoveries in biology in the last 50 years is that the brains of all young animals, including children, go through critical periods when they are particularly receptive to learning or mapping different forms of information.
Swedish scientists David Hubel and Torsten Wiesel received a Nobel Prize in 1981 for their experiments with newborn kittens. By sewing shut one eyelid of a kitten during its critical period from the third to the eighth week of its life, they found the visual areas in the brain map that would normally process input from the shut eye failed to develop, leaving the kitten blind in one eye for its entire life.
Thanks to their discovery, children born with cataracts no longer face blindness. Instead of waiting until they are older, these children are sent for corrective surgery when they are still infants. This way, their brains receive the light they need to form crucial connections during their critical period, which, like that of kittens, is short-lived.
Babies and young infants can pick up new words and sounds effortlessly during the critical period of cortex development. After age one it gets more difficult, but it is still much easier for children to learn new words. Whether these words are all from one language or from two or more doesn’t matter. All of the words—English, French, Russian, etc.—are stored in the same brain map.
After age 10, learning new words becomes progressively harder until, as adults, it is exceedingly difficult. The older you get, the more you use your native language and the more it comes to dominate your linguistic map. You still have brain plasticity, but your mother tongue rules. Your brain trains itself to not pay attention to foreign sounds, and the space in your head dedicated to language gets rather crowded.
The exciting news about “critical-period plasticity” is that it may be possible to reopen it so that adults can pick up languages the way children do. Scientists have learned that the part of the brain that allows us to focus our attention, the nucleus basilis, is “turned on” and stays on during the entire critical period. Once it is turned on, we not only pay attention to what we are experiencing, we also remember it. Our brains are in an extreme plastic state.
In experiments with rats, Dr. Michael Merzenich has reopened their critical-period plasticity by artificially turning on and keeping on their nucleus basilis using microelectrodes and an electric current. Someday (no one knows when) the same thing will be done with humans, using microinjections of certain drugs or chemicals. Just imagine how great this will be. With hardly any effort at all, you’ll be able to learn Swahili and speak it without an accent!