| Abstract: |
BACKGROUND: Acquired alexia can result from impairment in either the direct (lexical) or indirect (nonlexical) reading routes. The direct route involves visual word knowledge, is supported by semantics and used to read familiar words, is especially important in irregular word reading, and cannot be used to read unfamiliar or nonwords. The nonlexical or indirect route involves parsing graphemes into component parts, application of grapheme to phoneme correspondence rules, and blending of graphemes, and is pertinent when reading unfamiliar or nonwords. Impairment of the indirect route results in either phonological or deep alexia. Several investigations have reported successful attempts in the rehabilitation of indirect route processing with minimal generalisation to untrained items. The present study reports treatment of indirect route processing using a phonological treatment approach typically used for individuals with developmental dyslexia. AIMS: The aim of the present study was to investigate effects of a phonologically based rehabilitation programme on reading abilities for two adults with acquired alexia and impairment of indirect route processing. The following research questions were asked: (1) Does phonological treatment improve reading comprehension and the ability to read aloud? (2) Does treatment generalise to untreated behaviours? (3) Are treatment and generalisation effects maintained following treatment termination? METHODS AND PROCEDURES: Two subjects who suffered a left hemisphere cerebral vascular accident participated in this study. A single-subject multiple baseline design used pre and post testing and repeated treatment, generalisation, and control probes. Data were analysed using visual inspection from three judges uninvolved in this study as well as effect size (f-statistic). OUTCOMES AND RESULTS: Results showed a treatment effect for real word reading aloud as well as improvement in post-test measures of real word comprehension. The presence of a treatment effect was defined and judged to be dependent on the presence of generalisation to untreated stimuli (research question 2). Finally, treatment and generalisation effects were maintained following treatment termination. CONCLUSIONS: The phonologically based treatment programme utilised in this study was effective in treatment of the indirect route process with some effects of generalisation to behaviours such as consonant repetition, nonword repetition, real word repetition, oral praxis, and auditory syllable discrimination. These results support the view that language has a core phonological processor which comprise a neural network that links representations responsible for articulatory motor programming and naming. This study also supports the notion that phonologic treatment may be beneficial in individuals with aphasia and acquired alexia. |
