Robin van Rijthoven

13 General introduction 1 with a base in neurobiological development (American Psychiatric Association, 2013). There seems to be consensus that dyslexia can best be understood from a Multifactorial model (seeCatts&Petscher, 2020; Cattset al., 2017;McGrathet al, 2020;O’Brien&Yeatman, 2021; Pennington, 2006; Van Bergen et al., 2014b). According to the Multifactorial model multiple factors combine and/or interact and cause difficulties in learning to read and spell (see Catts & Petscher, 2020). These factors occur at genetic, neural, cognitive, and environmental level (see Zuk et al., 2020). A large amount of research supports the notion that reading and spelling problems of children with dyslexia are associated with deficiencies in phonological processing on the cognitive level (see Pugh & Verhoeven, 2018). These deficiencies are reflected in problems in manipulating speech sounds that may hamper the grasping of the alphabetic principle (Bradley & Bryant, 1983). This socalled phonological deficit seems to underlie most reading and spelling problems of children with dyslexia (Melby-Lervåg et al., 2012, Pennington et al., 2012) and causes inaccurate or underspecified phonological and orthographic representations (Conrad, 2008). This, as a result, leads to problems in accurate and fluent reading and spelling among children with dyslexia (Lyon et al., 2003). The phonological deficit is domainspecific and independent of other linguistic abilities (Shaywitz et al., 2003). Already at a preliterate age, the phonological deficit influences the development of reading and spelling. Children at risk for dyslexia have been found to lag behind in phonological awareness, rapid naming, and verbal working memory (Melby-Lervåg et al., 2012; Puolakanaho et al., 2007). Phonological awareness is the awareness of spoken sounds in a language and has been found to be related to the process of mastering the systematic grapheme-sound correspondences and contribute to accurate and fluent word decoding (Melby-Lervåg et al., 2012) and spelling (Landerl &Wimmer, 2008). Rapid automatized naming involves accurate and efficient storing of detailed phonological or orthographic information, and has been found to be closely related to word decoding as well (Georgiou et al., 2012; Norton & Wolf, 2012). Verbal working memory is the ability to store verbal information temporarily and can be a constraint when excessive demands are being made, such as is the case in reading and spelling (Swanson et al., 1996). Despite the fact that the phonological deficit is often associated with reading and spelling problems in children with dyslexia, not all children with reading and spelling problems have the same underlying deficit (Catts et al, 2017; O’Brien & Yeatman, 2021; Pennington et al., 2012; Snowling, 2008) and there is considerable variation in the causal base of reading and spelling difficulties (O’Brien & Yeatman, 2021; Pennington et al., 2012; Snowling, 2008). According to Multifactorial causal models of dyslexia, reading and spelling problems and variation in these problems could be caused by a complex interplay of weaknesses, but also strengths (Astle & Fletcher-Martin, 2020). Following a Multifactorial account of dyslexia, an important question is to what extent children with dyslexia may compensate for weaknesses with relative strengths.