Investigating the performance and underlying mechanisms of a novel screening measure for developmental dyslexia: Implications for early identification

Developmental dyslexia is a common disorder affecting around 10% of the British population characterized by difficulties with reading despite adequate intelligence and education (IDA, 2007). Although most researchers and practitioners would agree that early identification is key in limiting negative consequences of reading problems, this is still difficult to achieve due to theoretical and practical inconsistencies in the field. This thesis focuses on investigating a novel, computer and tablet-based “dot-to-dot” (DtD) task that may aid the process of identification particularly in pre-reading children and English as additional language (EAL) individuals who, by definition, are more susceptible to misidentification. Performance on this task was tested in primary school children (N = 457) and in adults (N = 111) together with a set of dyslexia-sensitive, vision and reasoning tests. Performance on DtD (especially the first sector error) demonstrated significant differences between children at high and low risk of dyslexia (as assessed by Lucid Rapid), as well as between children prospectively identified as poor and typical readers. DtD measures added small but statistically significant unique contributions to the models predicting reading scores and reading level group membership, and DtD measures could distinguish between poor and typical readers as well as between adults with and without diagnosed dyslexia. The findings provide evidence for the DtD test to be a useful addition to existing tests as it presumably relates to a number of mechanisms in line with automaticity and cerebellar deficits theories of dyslexia. It also has a potential to identify a distinct type of dyslexia that is not related to phonological processing which has important theoretical and practical implications.