Phonological treatment of naming deficits in aphasia: Model-based generalization analysis

Abstract A phonologically based treatment was implemented to train oral picture naming in four aphasic subjects with severe word-retrieval deficits. An initial assessment based on current cognitive neuropsychological models of naming indicated different levels of phonological and/or semantic deficits underlying naming failure across the subjects. Using a single-subject multiple baseline design across behaviours and subjects, the effects of treatment were evaluated by daily probing of both trained and untrained items across lexical tasks: oral naming, oral reading, and written naming. Results indicated successful acquisition of trained naming targets for the four subjects, and varied patterns of response generalization to naming of untrained phonologically and semantically related pictures, and to oral reading and written naming for the same words. Baseline levels of oral reading performance were noted to predict success in oral naming treatment. Differences in generalization patterns across tasks are discussed with regard to the varying functional levels of breakdown noted across subjects. This investigation demonstrates the utility of cognitive models in guiding the development of appropriate treatment strategies and generalization measures, and the importance of incorporating single-subject experimental designs in documenting changes associated with treatment.