Rehabilitation of reading and writing deficits
In a recent study (Johnson, Ross, & Kiran, under review), we examined the efficacy of a comprehensive treatment for word-level deficits in oral reading or writing-to-dictation. Eight patients were treated in either reading or writing via a multi-step protocol targeting key processes and skills within the dual-stream model of language processing. Though treatment was focused on reading or writing, patients’ accuracy was monitored on trained items and untrained but semantically or orthographically related items in both modalities. Treatment significantly improved patients’ ability to accurately process trained items in their trained modality; we also found improvement on trained and untrained items in both modalities. Patients made significant progress on a subset of treatment steps, suggesting that changes in reading and writing were related to a number of mechanisms, including enhanced lexical-semantic representations and access to these representations, sublexical conversion skills, and working memory processes. These results underscore the efficacy of our treatment protocol and highlight the value of addressing multiple aspects of the reading/writing system within the context of a single treatment.
Ross, Johnson, and Kiran (under review) recently developed a system to simultaneously, quantitatively, and qualitatively measure errors in reading and writing tasks. In this Dual-Route Error Scoring (DRES) system, errors are evaluated hierarchically in the sublexical and lexical routes according to proximity to a target. The sublexical score reflects the letter/sound-level accuracy of the production, including the length of response (in graphemes/phonemes) and the percent overlap with the target. The lexical score reflects the response as a whole unit, including the modality of response (e.g. oral reading, gesture, drawing, etc.) and the semantic relatedness. DRES was developed using data from a novel treatment study also recently completed in our lab (Johnson, Ross, & Kiran, under review) for eight patients with acquired alexia/agraphia.
These scores offer insight into the nature and degree of breakdown in print processing, while also allowing us to see changes as a result of treatment beyond what is captured by a correct/incorrect scoring paradigm. One capacity of the DRES system is to generate an error profile for each patient. This is done by plotting each response as a point on a graph, using the sublexical and lexical scores as x and y coordinates. A nonresponse is indicated by the bottom left corner (S0, L0), while a correct response is in the top right (S9, L9). It is possible to see from these results that the patient only experienced a small increase in correct responses (+2), however, substantial lexical and sublexical improvements can be evaluated with this system. DRES results reflect significant treatment effects, unique error profiles and specific error evolutions, and categorical error shifts in group-level analysis. The results of this study indicate that treatment-induced evolution of reading/writing can be meaningfully and comprehensively represented by this novel scoring system.
In two older studies, we examined the nature of crossmodal generalization in patients with reading and writing deficits.
Kiran (2005). A model-based treatment focused on improving grapheme to phoneme conversion as well as phoneme to grapheme conversion was implemented to train oral reading skills in two patients with severe oral reading and naming deficits. Initial assessment based on current cognitive neuropsychological models of naming indicated a deficit in the phonological output lexicon and in grapheme to phoneme conversion.
Using a single subject experimental design across subjects, the effects of treatment were evaluated by periodic probing of both trained and untrained regular words across lexical tasks: oral reading, oral naming, written naming, and writing to dictation. Results indicated successful acquisition of trained reading targets for both patients, as well as generalisation to untrained reading items, oral and written naming of trained items, and writing to dictation of trained and untrained items. Irregular words probed across the four lexical tasks did not demonstrate any improvement, as the trained grapheme to phoneme conversion skills were unsuccessful when applied to irregular words. The present experiment provides evidence for incorporating cognitive neuropsychological models in aiding the development of appropriate treatment protocols, and demonstrates the importance of rule-based learning, rather than compensatory strategies, in maximising the effects of generalisation.
Kiran, Thompson, & Hashimoto, (2001) investigated the effect of training sublexical conversion on improving oral reading of regular words in 2 patients with aphasia.
The aim of the study was to extend this work to investigate if training phoneme to grapheme conversion would result in improvement of writing to dictation of trained items and facilitate generalisation to untrained stimuli and untrained tasks. Using a single subject experimental design across three participants with aphasia, the effects of phoneme to grapheme conversion treatment were evaluated by periodic probing of both trained and untrained regular words across lexical tasks: writing to dictation, written naming, oral spelling, and oral naming. Results indicated that training phoneme to grapheme conversion resulted in improved writing to dictation of trained and untrained words in two out of three patients. In addition, improved written naming and oral spelling of trained words was observed. Marginal improvements were observed for untrained stimuli on written naming, oral spelling and oral naming.
The results of this experiment demonstrate the effectiveness of training sublexical conversion to improve written production deficits and to facilitate generalisation to untrained stimuli and untrained tasks. These results also complement findings of our previous study to suggest a more efficient method of improving single word production deficits than training each modality successively.