Chapter synthesis and thesis structure summary

The current chapter has discussed the background and rationale for the current investigation, emphasising the importance of the early identification of dyslexia and a value of including of non-language based tasks to aid the identification of dyslexia, particularly in assessing children and adults whose first language is not English. Increased movement of people between countries means that educational staff are often faced with children and adults from different language backgrounds who require adequate assessments to ensure that they are provided with the right support.

Identification of individuals with problems related to reading as early as possible and then providing them with appropriate intervention, as well as monitoring their progress along the way, seems to be the best approach to remediate the negative consequences of reading disability. Nurturing potential talents in these individuals may additionally help them to cope and to succeed in life. The importance of early identification allowing early interventions in children with English as an additional language was also highlighted. It has been argued that existent tests that rely on language skills may not always be the most accurate in child and adult populations who are bi- or multilingual. The need of an additional reliable tool that would be associated with other problems, such as motor or visual, is therefore proposed.

The lack of consistency in the definition of developmental dyslexia, and the way that it has been diagnosed previously and more recently, may cause problems in evaluating the quality of research conducted in different years. Different studies would naturally echo definitions appropriate to their times and the differences in findings due to this must be kept in mind. These complex issues related to defining dyslexia make the remediation of the problems even more challenging (Wanzek &

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Vaughn, 2007; Wanzek et al., 2013). The role of socioeconomic status in reading development, as well as various comorbidities, were also discussed in this chapter.

The incongruities of the definitions discussed in this chapter need to be borne in mind throughout the remaining chapters. The terms development dyslexia (DD), dyslexia, and reading disability (RD) will be used interchangeably in the literature review with the explanation of particular constructs employed by the researchers whose papers will be cited, where necessary.

Chapter 2 provides a discussion of the key theories which aim to explain dyslexia. The chapter explores the theories providing evidence for proximal causes (such as phonological deficits hypothesis) in addition to those working around the distal causes. The latter group of theories focuses around abnormalities in brain areas (such as visual pathway and the cerebellum) and learning processes (procedural learning hypothesis). It is crucial to discuss different theoretical models in order to understand the novel DtD task being investigated in the current thesis and to hypothesise which skills would be related to a good performance on this novel task.

Chapter 3 provides a description of the general methods used within the subsequent studies. Here, the detailed explanation of the DtD task is provided together with pilot and anecdotal evidence of its screening potential.

Chapter 4 is the first empirical study looking into the cross-section of children in three different age cohorts (nursery and Primary 1, Primary 3, and Primary 5) from three schools characterized with diverse socioeconomic backgrounds. Children were tested on a number of measures: the DtD test, phonological processing, memory, rapid naming, verbal and non-verbal reasoning. As the DtD software generates many variables presumably associated with different skills, a correlational analysis was conducted to identify whether any of the dyslexia sensitive or reasoning abilities were related to the DtD task. Dyslexia risk was estimated by the existing screening test (Lucid Rapid), and children were assigned to high, medium or low risk of

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dyslexia group. Group differences were investigated. The scores from this study were treated as a baseline to the following prospective investigation.

Chapter 5 offers a prospective investigation of the reading level (poor vs typical) group differences in the baseline measures and, most importantly, examines which of the many DtD and dyslexia-sensitive measures can accurately predict reading level (as a continuous variable) and reading level group membership (as a dichotomous variable). Furthermore, a detailed investigation of weaknesses found in poor readers and the impact of different operational definitions on the results are provided. The impact of the school children went to and their gender on their performance was also investigated. This chapter provides a more detailed discussion of the findings from both the cross-correlational and the prospective investigations.

Chapter 6 provides an investigation of visual perception in a subgroup of children to identify whether the performance on the DtD task is related to their sensitivity to stimuli preferentially activating low or high level visual processing pathways. The long lasting debate on the role of the magnocellular pathway and dorsal stream in dyslexia is addressed here by correlational and quasi-experimental designs.

Chapter 7 delivers a final empirical investigation of the potential use of the DtD test in indicating adult individuals with dyslexia. The adult participants were also tested on a range of dyslexia-sensitive and reasoning tasks in order to investigate the relationships between them and the DtD task.

Chapter 8 offers a general discussion of the findings of the thesis, together with their implications and directions for further research.………