GRADUAL EMERGENCE OF DEVELOPMENTAL LANGUAGE DISORDERS

This article presents a theory of normal and delayed development of la nguage. According to the theory, linguistic capacity develops in criti cally timed phases that occur gradually and sequentially. Normally, th e rapid accumulation of stored utterances activates analytical mechani sms that are needed for the development of linguistic grammar. Childre n with slowly developing brains have delays in the socially cognitive systems that store utterances, and a critical period for activation of experience-dependent grammatical mechanisms declines without optimal result. Continuing efforts to speak induct species-atypical allocation s of neural resources into linguistic service. It is speculated that t his compensatory activity leads to compensatory growth, which may ulti mately be revealed as volumetric symmetry of perisylvian areas. Becaus e rate of brain maturation is under genetic as well as environmental c ontrol, the stage is thus set for an impairment that will seem to be s pecific and a brain that will appear to be abnormal.