Robin van Rijthoven

142 Chapter 6 A unique feature of the phonics through spelling intervention in the current thesis is the relatively large amount of time spent on spelling in order to strengthen the bidirectional relationship between phonology and orthography. The intervention turned out to be beneficial for reading and spelling for children with dyslexia, which is in line with previous findings on the effectiveness of phonics interventions (e.g., Galuschka et al., 2014) and programs emphasising both reading and spelling among typically developing children (Conrad, 2008; Ehri &Wilce, 1987, Ellis & Cataldo, 1990). The reduction of all of the examined categories of spelling errors is in line with improvements that were found after interventions focusing on phonics, morphological, or orthographic instruction (Galuschka et al., 2020) and illustrates that phonics through spelling interventions may have a positive effect on both phonological and orthographic aspects of spelling development. The positive outcomes of this phonics through spelling intervention should be evaluated against positive effects on word spelling and rather inconsistent findings of reading-focused interventions, focusing on pseudoword and word reading (Kirk & Gillon, 2009; Lovett et al., 1989, 1990; Tijms, 2011; Tilanus et al., 2016). In contrast, our results showed that a phonics through spelling intervention is beneficial for spelling as well as for both pseudoword and word reading. It is evidenced that a combined emphasis on reading and spelling instruction helps building strong bi-directional relations between phonology and orthography and thus benefits reading and spelling development, probably because the phonology-orthography relation is stimulated to a bigger extent as spelling is more difficult than reading (Bosman & Van Orden, 1997). Although children in this study significantly improved, and many of them were no longer among the weakest 10% in word reading and spelling, it is important to note that after the intervention, most children remained weak readers and spellers compared to typically developing controls with substantial inter-individual variation in reading and spelling levels. Our results providemore insight in the influence of relative strengths and weaknesses of children on response to intervention. Phonological abilities (i.e., phonological awareness, rapid automatized naming, and verbal working memory) were not related to response to phonics through spelling intervention of children with dyslexia. This is in line with findings from other studies demonstrating the robustness of reading interventions that improve decoding accuracy notwithstanding the levels of phonological awareness (Felton, 1993; Tijms, 2011), rapid automatized naming (Heikkilä, 2015), or by improving both decoding accuracy and fluency notwithstanding their levels of phonological awareness, rapid automatized naming (Aravena et al., 2016; Tilanus et al., 2016), or verbal working memory (Tilanus et al., 2016). It turns out that, although most of these phonological abilities influence word and pseudoword reading and spelling before the intervention, there was no additional influence on response to intervention. This could indicate that the intervention is sowell tailored to the child’s needs that the phonological