Neuroscience. A critical issue for the brain

The notion that there is a "critical period" for learning in the first 3 years of life has cropped up widely in media reports recently. But although critical periods have been well documented for the development of sensory systems in the brain, especially vision, researchers differ over whether they exist for the development of the brain functions that underlie complex learning and thinking skills. Scientists do agree, however, that where critical periods do exist, they are not sharply defined, nor are they unique to the first 3 years of life, as has been conveyed in the media. The message should give hope to adults who may not learn with the ease of early childhood, but can still do it.