Bigraph-syllable blending therapy in deep dyslexia

Background: The evidence-base of therapy studies for reading difficulties is notably sparse, particularly for individuals with deep dyslexia. Research using grapheme-to-phoneme correspondence approaches to remediate the non-lexical reading route in deep dyslexia have been reported but with limited therapy success. The approach of bigraph-syllable blending training has met with some success enabling individuals with deep dyslexia to read single words containing these bigraphs. Aims: This study compares the effects of the bigraph-syllable pairing training method on oral reading for mid-high and low-frequency bigraphs in training and generalization items in an individual with deep dyslexia (DT). To inform the clinical practice, we also analysed DT’s ability to engage with the therapy cues (i.e. ability to process, generate and utilize the cues) to determine the most responsive component of the cueing hierarchy. Methods & Procedures: Detailed assessment indicated that DT showed deep dyslexia with severe difficulties reading non-words, alongside imageability effects and production of semantic errors. A single-subject multiple probe across behaviour design was employed to evaluate the efficacy of bigraph-syllable pairing therapy for training and generalization of bigraph sets containing mid-high and low-frequency bigraphs. DT’s engagement with the therapy cues were tracked across each of the therapy sessions. Generalisation effects were evaluated by measuring performance on untrained bigraph stimuli and change in performance from pre- to post-therapy on single word reading subtests. Outcomes & Results: Results reveal that post-therapy DT showed improvement in reading aloud for both mid-high and low frequency trained bigraphs, albeit to a different degree. Mid-high frequency bigraphs showed greater therapy effects than the low-frequency bigraphs. DT demonstrated that writing and copying were the most beneficial cues in supporting DT’s oral reading of bigraphs. He did not show any generalization to untrained bigraphs, but illustrated a reduction in imageability effects with improved reading accuracy for low-imageability single words, and improved ability to name letters. Post-therapy, he showed a significant reduction in omission errors and a significant increase in unclassifiable errors in reading aloud. Conclusions & Implications: This study demonstrated the efficacy of bigraph-syllable pairing training for improving oral reading abilities and reducing the imageability effects in an individual with deep dyslexia. The findings from client’s responsiveness with different cues during the therapy showed that writing and coping is a useful strategy for improving reading aloud abilities