Critical window for language development found


Brain scans taken by scientists at King's College London, and Brown University, indicate that a critical window for language development exists between the ages of two and four, as the brain's wiring develops to process new words.

The findings put fresh emphasis on tackling disorders causing language delay as early as possible, as any environmental influences on brain development will be strongest in infanthood.

In the research experiments, brain scans taken of myelin - the insulation that develops from birth within the circuitry of the brain - showed that the distribution of myelin is fixed from the age of four, suggesting the brain is most plastic in very early life.

This explains why immersing children in a bilingual environment before the age of four gives them the best chance of becoming fluent in both languages.

Dr Jonathan O'Muircheartaigh, who led the study, told the BBC: "Since our work seems to indicate that brain circuits associated with language are more flexible before the age of four, early intervention for children with delayed language attainment should be initiated before this critical age.

"This may be relevant to many developmental disorders, such as autism, since delayed language is a common early trait."

Babies have a vocabulary of up to 50 words at 12 months but by the age of six this has expanded to about 5,000 words.