Robin van Rijthoven

138 Chapter 6 In order to become a proficient reader and speller, an efficient recurrent network of phonological, orthographic, and semantic representations needs tobe built (Seidenberg & McClelland, 1989). According to the lexical quality hypothesis word representations can be characterized by two dimensions: specificity and redundancy. Lexical specificity refers to the degree to which words are specified phonologically, semantically, and orthographically. Redundancy refers to the extent that lexical representations can be retrieved from memory; lexically and/or sublexically (Perfetti, 2007). Children with dyslexia stay behind in their reading and spelling development and there seems to be consensus that multiple factors combine and/or interact to cause difficulties in learning to read and spell (Catts et al., 2017; McGrath et al, 2020; O’Brien & Yeatman, 2021; Pennington, 2006; Protopapas, 2019; Van Bergen, 2014b). For most children with dyslexia, the phonological deficit underlies reading and spelling problems (Lyon et al., 2003; Snowling & Hulme, 2021) by causing inaccurate and underspecified phonological pathways (Conrad, 2008; Nation & Snowling, 2004). However, not only weaknesses but also strengths may be related to reading and spelling outcomes (Catts & Petscher, 2020) and are important to build on when compensating weaknesses (Protopapas, 2019). When phonological representations are weak, other parts of the triangular framework (Seidenberg & McClelland, 1989) could become more important and relative strengths in semantic and orthographic representations could be sources of compensation for these weaker phonological representations. Although prior research mentioned the possible compensatory role of semantic abilities on reading (e.g., Duff et al., 2015; Gijsel, 2007; Haft et al., 2016; Hulme et al., 2010; Torppa et al., 2010) and spelling (e.g., Ouellette, 2010) and the possible compensatory role of stimulating orthographic representations on learning to spell and read (e.g., Conrad, 2008), these factors received scant attention in research so far among children with the actual diagnosis of dyslexia. In contrast with previous research, in the present thesis, semantic abilities are defined as much broader than just vocabulary. It is generally known that semantic abilities involve more than vocabulary alone, especially because the specificity and redundancy of the lexical representations can be considered important (Perfetti & Hart, 2002). Therefore, the aim of this dissertation was to study these two possible sources of compensation for phonological shortcomings and thereby the reading and spelling problems of children with dyslexia in the Netherlands. The first research question was to what extent deep and broad semantic abilities compensate for a phonological deficit in reading and spelling development in children with dyslexia. The second research question was to what extent a phonics through spelling intervention could benefit reading and spelling development of children with dyslexia with varying cognitive and linguistic profiles.