The use of the term dyslexia to describe children who have difficulty learning to read is one that has for many years generated a great deal of controversy. Is it a label employed by ambitious middle-class parents who are disappointed by their child’s failure to be as academic as they’d hoped, or is it a genuine learning difficulty that warrants due recognition and specialist teaching?
One of the criticisms that has been directed repeatedly at the use of the term dyslexia is that it carries the assumption that an inherent cognitive deficit results in the child struggling to learn to read – specifically, a weakness in phonological (speech sound) processing that makes it hard for the child to learn to decode words using their phonic knowledge and so to read and spell accurately.
However, as Elliott and Grigorenko argue in their book The Dyslexia Debate (2014), it is not possible at the current time to separate poor readers into clear causal groups, based on either biological or cognitive phenomena. Nor, they continue, can we identify a biologically- or cognitively (presumably phonologically) – based dyslexic subgroup within a larger pool of poor readers.
They appear to particularly object to the so-called vast dyslexia industry which provides assessments and interventions that are accessible to middle class families but are denied to disadvantaged families. Elliott and Grigorenko also claim that there is an erroneous belief that a diagnosis of dyslexia can result in appropriately tailored forms of intervention that address the child’s underlying deficit and which will therefore improve their reading capabilities.
The authors conclude by calling for an end to the dyslexia label and for it to be replaced by more detailed descriptors of the deficits that underpin reading difficulties in a given child. Following on from this, they highlight the need for assessment for intervention (as opposed to diagnosis) which will give children access to the most effective evidence-based interventions at as early an age as possible.
Dyslexia: All or nothing
While not disagreeing with these authors’ conclusions in relation to assessment for intervention, I would argue that their view of dyslexia is based on an outmoded, single deficit model. This model describes three different levels of study in a causal chain: the biological, the cognitive and the behavioural (see Figure 1). The single deficit model assumes that first, dyslexia is ‘all or none’ (i.e. you have dyslexia or you don’t), and second, that dyslexia must have a single biological (genetic/neurological) and a single cognitive causal basis.
Is dyslexia a dimensional disorder?
However, there is compelling evidence that indicates that dyslexia is a dimensional, not an ‘all or none’ disorder; there are no clear cut-off criteria and having a phonological deficit is in itself not sufficient to cause dyslexia. Indeed, its expression may vary in individual children and over the course of development, dependent on a combination of what are termed risk and protective factors.
Risk factors include not only having a phonological deficit, but also additional risks such as dyslexia occurring in the context of persisting (oral) language problems and the presence of co-occurring learning difficulties such as attention problems, maths difficulties or visual motor problems; indeed, it has been estimated that as many as 70% of children with dyslexia will have at least one co-occurring learning difficulty.
Protective factors might include having good verbal abilities (which provide a compensatory resource), as well as positive environmental experiences such as early identification, accessing high quality intervention and having supportive parents. Some individual children with dyslexia will go on to have a successful outcome and even go onto further education; others experience high levels of academic failure which limit not only their occupational opportunities but can also impact their overall well-being and even their mental health.
Which outcome prevails depends on the severity of the learning difficulty and the balance of risks versus protective factors. Non-literacy cognitive skills, additional risk factors and environmental experiences that impact outcome are sometimes referred to as moderator variables, which can be either positive or negative. The impact of moderator variables on outcome is expressed in Figure 2.
Responding to intervention
Viewed from this multiple deficit perspective of dyslexia, it is possible to agree with Elliott and Grigorenko’s broad pedagogic recommendations while at the same time disagreeing with the arguments that inform these. On a more positive note, this recent debate has resulted in the consensus of opinion that the term dyslexia or literacy disorder should be most appropriately reserved for those individuals with persisting reading difficulties who have not responded to robust and intensive intervention. Indeed, it has been suggested that the slow response to intervention typically seen in many dyslexic children might be a better way of identifying these children than measured reading skills.
Arriving at an understanding
Personally, I do not think it matters whether we describe an individual child’s reading difficulty as dyslexia or a specific reading problem or a literacy disorder, as long as we recognise that it is important to arrive at an understanding of the nature of their difficulties and how they might be addressed so as to improve their educational outcome and overall well-being.
Multiple deficit models have been very influential in enabling us to develop more effective assessment and intervention methodologies. This means that our assessments and interventions can be directed in such a way as to take account of dimensionality, co-occurrence, risk versus protective factors and the child’s broader learning environment.
In assessing a child’s reading difficulties, it is not enough to merely administer a test of single word reading; literacy is a multi-component skill and this should be reflected in the administration of a wide range of tests that cover reading accuracy, reading speed, reading comprehension, decoding ability, spelling and written narrative skills.
Phonological tasks that function as cognitive ‘markers’ (or diagnostic indicators) of dyslexia include measures of phonological awareness (e.g. phoneme blending or deletion tests), short-term verbal working memory (e.g. digit and word memory span tests) and phonological processing (e.g. rapid letter or digit naming tests). Cognitive level testing that targets language skills is needed for those children who have reading comprehension difficulties and for those whose dyslexia is occurring in the context of developmental speech and language delay or disorder.
Of course, simply providing a ‘shopping list’ of tests does not provide a meaningful and pedagogically useful evaluation; tests need to be interpreted within the context of the child’s broader learning abilities, their attainments in other educational domains, such as maths, the strong likelihood that they have co-occurring learning difficulties and determining which these are, the availability of protective resources and their home- and school-based learning environment.
Similarly, approaches to intervention need to go beyond teaching reading, spelling and underlying phonological skills and extend to contextualising literacy instruction within a broad language-based curriculum. Children with word level reading and fluency difficulties require interventions that target their phonological and decoding deficits and which are delivered within a structured multisensory teaching framework that also provides the opportunity for frequent reading practice.
A different type of intervention
Children who have language difficulties which commonly co-occur alongside dyslexia and those with reading comprehension problems require an intervention that promotes comprehension, narrative and in particular vocabulary skills, both within oral- and text-based contexts.
Spelling presents a challenge for children with dyslexia, requiring the adoption of intervention strategies that go beyond teaching phoneme-grapheme correspondence and which exploit the greater orthographic regularity evident in larger units such as morphemes (units of meaning).
Interventions need also to address co-occurring learning difficulties, which may mean including targeted maths programmes, promoting the use of technology for children with visual motor and handwriting problems, and creating additional in-classroom accommodations to support the child with attention challenges.
Broader management issues of relevance to almost all children with specific learning difficulties include empowering parents to support their child, setting in place appropriate allowances in formal examinations, finding means of engaging and maintaining the child’s motivation, encouraging the child to capitalise on their strengths (being highly verbal or visually creative, being good at maths or technology), and maximising the resources within the child’s home- and school-based learning environments.