Authors: s Hugh W. Catts, Autumn McIlraith, Mindy Sittner Bridges, Diane Corcoran Nielsen.
Publication: Reading and Writing (Springer). 30, 613–629 2017 | DOI: 10.1007/s11145-016-9692-2
Participants were administered multiple measures of phonological awareness, oral language, and rapid automatized naming at the beginning of kindergarten and multiple measures of word reading at the end of second grade. A structural equation model was fit to the data and latent scores were used to identify children with a deficit in phonological awareness alone or in combination with other kindergarten deficits. Children with a deficit in phonological awareness in kindergarten were found to be five times more likely to have dyslexia in second grade than children without such a deficit. This risk ratio substantially increased with the addition of deficits in both oral language and rapid naming. Whereas children with one or more kindergarten deficits were at heightened risk for dyslexia, some of these children were found to be adequate or better readers. These results are discussed within a multifactorial model of dyslexia that includes both risk and protective factors.
Perhaps more problematic for the phonological core deficit model is the observation that some individuals with a phonological deficit do not
demonstrate the expected word reading problems that are the hallmark of dyslexia. (Pennington et al., 2012 Snowling, 2008). For example, Pennington et al. (2012) showed that in two large samples of children there were numerous children who had a significant deficit in phonological awareness but no deficit in word reading. Snowling and colleagues (Moll, Loff, & Snowling,
2013; Snowling, Gallagher, & Frith, 2003) have also reported that unaffected siblings with a family history of dyslexia may have a phonological deficit but no marked word reading problem (also see van Bergen, van der Leij, & de Jong, 2014).
We defined dyslexia as a severe impairment in the single word reading. This was operationalized as performance below the 10th percentile on the word reading factor score in second grade. Similarly, we defined a deficit in
phonological awareness as performance below the 10th percentile on the phonological awareness factor score in kindergarten.
Further results indicated that of the 63 children with a deficit in phonological awareness, 47.6% had dyslexia at the end of second grade. This compared to only 8.5% of those who did not have a deficit in phonological awareness.
Perhaps the most novel findings in the study concerned children with a deficit in phonological awareness but no significant difficulties in learning to read words. Such cases are especially relevant to multifactorial models of dyslexia but have received relatively little attention in the literature.
The school district in which we worked had participated in Reading First
and Early Reading First Programs associated with the No Child Left Behind Act (2002). These programs were designed to improve reading instruction in young children, and consequently, our participants had excellent instruction in word reading. Almost all of the children we identified with a phonological deficit also had received small group supplemental instruction (Tier 2)
during kindergarten (N=58). Half of these children were in an experimental condition and received intervention by our research team and the other half received intervention in a business-as-usual condition. The latter division did not appear to impact reading outcome since children who had or did not have dyslexia in the current study were approximately equally represented in
the experimental and business-as-usual conditions. Also, any differences, if they had been present, were unlikely to explain outcomes since follow-up testing in an earlier study showed no significant difference between intervention conditions on reading outcomes (Catts, et al., 2015)
Catts, H.W., McIlraith, A., Bridges, M.S. et al. Viewing a phonological deficit within a multifactorial model of dyslexia. Read Writ 30, 613–629 (2017). https://doi.org/10.1007/s11145-016-9692-2