Good Readers but Poor Spellers:
Is morphological processing the key to understanding compensation in successful dyslexic adults?
Historically, most work on dyslexia has focused on reading deficits, but in fact deficits in spelling may be more persistent. While 25% of adults with dyslexia have been shown to recover from earlier deficits in reading (known as ‘compensation’), spelling deficits persist in almost all dyslexic adults. To date, little is known regarding the mechanisms that aid or hinder spelling compensation amongst school leavers with dyslexia.
Enduring spelling difficulties are important to consider for both individuals with and without dyslexia and the UK as a whole because of the widespread negative implications spelling, and writing difficulties have on day-to-day functioning in the workplace and school. The UK Department of Education reported in 2016 a year-on-year negative progress for GCSE students in English. One in nine children leave school early and students with dyslexia have 2.5 times greater high school drop-out rate (Gerber, 2009), impacting not only the individuals but society and economies. Additionally, the OECD 2016 PISA rankings placed the UK 22nd in reading/writing, trailing countries like Vietnam, Poland and Estonia. This demonstrates a need for a greater research focus nationally on spelling and writing skills in the UK.
It has been theorised that adults with dyslexia may be able to overcome their initial spelling deficits through a reliance on the greater consistency offered by larger orthographic units such as morphemes (Pennington et al., 1986). Morphemes are smallest linguistic units of meaning, used to form more complex words (e.g. Farm –er to make farmer). The deconstruction of a target word into its base morphemes provides additional information to the reader beyond form, such as syntactic, semantic and phonological information, which has been shown to aid in reading and spelling performance (Law et al. 2015 & 2017). Although neglected in previous studies of reading development and achievement, recent studies have begun to recognize morphology as a contributing variable in word recognition, independent of other psycholinguistic variables and/or reading and reading-related skills (Deacon & Kirby, 2004; Law et al., 2016). However, few studies have examined the use of morphemes during spelling production, particularly in the generation of correct spellings and in dyslexia.
Of the studies that have investigated the role morphological skills play in literacy compensation, inconsistencies are apparent. On the one hand, high functioning adults with dyslexia show a relative strength in morphological skills, which has been attributed to observed levels of reading compensation (Cavalli et al., 2017; Law et al., 2015 & 2017). On the other hand, younger children with dyslexia show weaknesses in morphological skills (Breadmore & Carroll, 2016a, 2016b; Carroll & Breadmore, 2017). It could be that the individuals with dyslexia that learn to compensate for their literacy difficulties do so by using morphology, while those that do not also have more persistent difficulties with morphology. However, the role of morphological skills in spelling and compensation has not been directly assessed, and morphology has been neglected in existing models of spelling.
To address this gap, this research has focused on the strengths and weakness school leavers with dyslexia have in spelling. This work has provided new insights into the skills and strategies that are characteristic of proficient and impaired spelling and identify mechanisms that aid or hinder the ability to compensate for spelling difficulties in dyslexia.
This work will not only broaden the characterization of compensatory factors within the current explanatory models of dyslexia but additionally provide empirical support for new targeted intervention schemes ultimately helping literacy impaired individuals realise their academic and professional potential.