The status of metalinguistic skills in reading development.

Diane Sawyer (this issue) presents an account of reading development and its disabilities that stresses the contribution of a hierarchy of metalinguistic skills in the segmentation and manipulation of speech. Two of her central claims are discussed: (1) Failure to master the productive relationship between spelling and sound may often originate in difficulty in the prerequisite ability to carry out phonemic segmentation; the population so affected may include both "true" and "apparent" types of dyslexia, with rather different prognoses; and (2) a range of hierarchically and temporally organized sublexical metalinguistic speech skills govern the timecourse of reading development. Evidence from cognitive neuropsychological case reports is reviewed for its bearing on these claims and for its implications for the strong metalinguistic hypothesis, which contends that explicit, conscious mastery of the relationship between phonology and orthography is a necessary (and perhaps sufficient) precondition for the development of fluent reading.