RESPONSIVENESS TO THE DECLARATIVE PHASE OF THE INTERVENTION Letter knowledge

According to the reading development model (Ehri, 1991, 2014; Ehri & McCormick, 1998),

it is supposed that children have a full letter knowledge at the end of first grade. As demonstrated in Chapter 2 and Chapter 5, Dutch children with dyslexia did not comply

with this assumption. Both second and third graders with dyslexia had an incomplete letter knowledge when they entered the clinic. Based on the data in the present dissertation it remains unclear whether the problems with their letter knowledge is due to dyslexia or the educational system in general. In previous studies, it has been demonstrated that school- based phonics instruction might be extremely difficult for English children with dyslexia (Lovett, Barron, & Benson, 2003). However, given the fact that letter knowledge in Dutch is extremely consistent it can be discussed whether problems with letter learning in our case can be considered necessarily evident in the case of dyslexia. Nevertheless, whereas children with dyslexia in the present dissertation were, for unclear reasons, not able to fully benefit from the phonics instruction and remediation at school, the results in Chapter 3 revealed a successful improvement of children’s letter knowledge during the first, declarative phase of the clinical intervention. This success is in line with previous findings (Hulme, Bowyer-Crane, Carroll, Duff, & Snowling, 2012). To evaluate the development of children’s letter knowledge in more depth, a distinction was made between the accuracy and speed of naming grapheme-phoneme correspondences before and during the intervention. On both measures, children with dyslexia were able to improve their ability to name grapheme-phoneme correspondences accurately and fast. These findings are promising as a good naming of grapheme-phoneme correspondences represents good letter knowledge which precedes successful decoding strategies (Castles & Coltheart, 2004; Share, 2004; Snowling & Hulme, 2011).

Thus, results showed catch-up effects of children with dyslexia with typically reading peers during the clinical phonics approach on the accuracy and speed of letter naming. It leaves still open the question what determines the success of the clinical approach on these aspects, as children with dyslexia were resistant to school-based phonics instruction and remediation.

Reading and spelling abilities

As the children with dyslexia improved their letter knowledge during to the declarative phase of the sustained intervention, it can be hypothesized that also their decoding and coding skills, which is reflected in word and pseudoword reading and spelling abilities, will improve (Chen & Savage, 2014; de Graaff, Bosman, Hasselman, & Verhoeven, 2009; Devonshire, Morris, & Fluck, 2013; Hulme et al., 2012). Results in Chapter 3 indeed showed the successful improvement of pseudoword reading (accuracy and efficiency) and spelling accuracy, with an increase larger than that of the typically reading control group. However, on real word reading, results showed that children with dyslexia improved their accuracy and efficiency skills, but their change in skills was comparable with those of their typically reading peers. In other words, where children with dyslexia show catch-up effects with

typically reading peers on their letter knowledge, pseudoword decoding accuracy and efficiency and spelling accuracy, there was no catch-up effect in the reading of real words. This finding is not in line with Verhoeven and Keuning (2018) who found that difficulties in readers with dyslexia manifested themselves more for pseudowords than for words. Neverthless, in the present thesis, Dutch children with dyslexia continue to have severe problems with the direct word recognition, the direct route of reading (Barth, Catts, & Anthony, 2009; Ehri, 2005; Ehri, 1997; Gottardo, Chiappe, Siegel, & Stanovich, 1999), even after the first, declarative phase of a clinical phonics intervention. Based on a study by van der Kleij, Segers, Groen, and Verhoeven (2017), it is even likely that these arrears on real word reading will remain on the long term.

An explanation as to why children with dyslexia did not show catch-up effects in reading real words, can possibly be derived from the content of the intervention approach. In the approach, an important part is reserved for the learning of symbolic scaffolds which tends to simplify the structure of words. The explicit focus on the learning of grapheme- phoneme correspondences using meaningful symbols could possibly stimulate grapheme recognition rather than direct word recognition, causing catch-up effects for the accuracy and speed of grapheme-phoneme naming, pseudoword reading and spelling, but not for word reading. Another explanation why no catch-up effects were found on real word reading is the rapidly increasing length of words in the real word reading task. Successful reading in children with dyslexia is influenced by the length of words (Martens & de Jong, 2006). A final explanation is the limited duration of the declarative approach, which may have been too short to achieve transfer-effects.

To conclude, compared with typical readers, children with dyslexia showed an improvement of their letter knowledge, their pseudoword reading and spelling abilities. It shows the success of the declarative phase of the sustained intervention in Dutch second graders with dyslexia, although children with dyslexia were still lagging behind their typicaly reading peers.