Individual cognitive analysis of competent and impaired reading

A cognitive model of basic reading functions is described together with experimental procedures that may be used to investigate the efficiency and operation of its components in individual subjects. Illustrative results obtained from competent and impaired readers aged about 11 years are presented. Competent reading, defined in terms of efficiency within a morphemic route to phonology, may be achieved despite quite marked inefficiencies in adjacent systems, including a grapheme-phoneme translation process. Both these functions are typically impaired in poor readers, although the balance of relative impairment may vary. The index of relative impairment may be used to define subtypes of disability, referred to as phonological dyslexia and morphemic dyslexia. However, this procedure did not identify groups of subjects who shared a common set of processing characteristics. Some theoretical and diagnostic implications are discussed.