No effect of orthographic neighbourhood in treatment with two cases of acquired dysgraphia
ABSTRACT Background: Studies on the nature of processing within the spelling system have provided evidence for interactivity, where activation between levels of processing flows bidirectionally. In particular, activated letters at the level of the graphemic buffer feed activation back to the lexicon. As a consequence lexical neighbours are activated, which in turn reactivate the graphemic buffer, supporting target selection and leading to an effect of orthographic neighbourhood size in spelling. As a consequence of this feedback, treating words with many neighbours may be more beneficial, and generalisation may be more likely to occur. Aims: The current study aimed to further examine this interactivity, and in particular the role of orthographic neighbourhood size in both treatment effects and generalisation, in the treatment of two individuals with acquired dysgraphia. Two phases of copy and recall treatment were conducted to investigate if orthographic neighbourhood size modulates treatment effects: in the first phase, treated words had no orthographic neighbours, in the second phase, treated words had many neighbours. Untreated control sets were used to investigate the influence of neighbourhood size on potential generalisation across items. Main Contribution: Results showed that treated items improved, however neighbourhood size did not significantly influence the size of the treatment effect for either participant, and no clear evidence was found for generalisation to untreated items. Conclusions: It is argued that (1) the amount of feedback from the buffer to the lexicon was reduced in the participants in this study, and consequently the treated items provide insufficient activation to orthographic neighbours or (2) the effect of feedback from neighbours is small compared to effects of treatment, resulting in similar results for treated words with and without neighbours. This study informs the relationship between spelling impairment and effects of treatment. Furthermore, the absence of generalisation emphasises the importance of choosing functionally relevant items for treatment.