Rapid reacquisition of native phoneme contrasts after disuse: you do not always lose what you do not use.

Infants attune to their birth language during the second half of infancy. However, internationally adopted children are often uniquely required to attune to their birth language, and then reattune to their adoptive language. Children who were adopted from India into America at ages 6-60 months (N = 8) and had minimal further exposure to their birth languages were compared to age-matched American non-adopted controls. Without training, neither group could discriminate a phonemic contrast that occurs in their birth language but not in English. However, after training on the contrast, the adopted group (N = 8) improved significantly and discriminated the contrast more accurately than their non-adopted peers. While English had explicitly replaced the birth language of the adopted sample, traces of early exposure conferred privileges on subsequent learning. These findings are consistent with behavioral and neurophysiological data from animals that have identified some of the mechanisms underlying such a 'retention without further use' phenomenon.