Intervention for Dyslexia - The British Dyslexia Association

4 Screening and assessment
4.1 Identifying children with dyslexia
In the context of this review, the chief purpose of screening and/or assessment is to
identify children who require intervention. However, assessment can also play a role in
determining which particular intervention programme would be most appropriate, in
shaping the delivery of that programme (e.g. starting points, amount of overlearning
incorporated, rate of progression expected) and in evaluating the impact of an
intervention on a given child or group of children.
Traditionally, the task of identifying children with dyslexia was exclusively carried out by
educational psychologists, primarily using psychological instruments that were ‘closed
tests’ (i.e. restricted to use by qualified psychologists). It is not within the scope of this
review to provide a full coverage of the ways in which dyslexic children can be identified
by educational psychologists. Detailed descriptions of methods and tests are provided
elsewhere (e.g. Beech & Singleton, 1997; Reid, 2003; Thomson, 1990; Turner, 1997).
Increasingly, however, teachers are taking on the task of identifying dyslexic pupils,
partly because the level of demand stimulated by increased awareness of dyslexia
cannot be met by the very limited number of educational psychologists available, but
also because of the availability of screening tests and assessment instruments that
teachers are entitled to use. The chief focus of this chapter will therefore be on
screening and assessment methods that are accessible to teachers.
4.1.1 Intelligence and discrepancy
Until relatively recently, the identification of discrepancy between the child’s IQ and their
attainments in literacy was a key part of the diagnostic process (see Section 1.2.2 for
explanation of the discrepancy criterion). Over the last two decades, however, there has
been a growing reaction against the use of IQ in determining dyslexia, largely because
poor readers whose reading skills are discrepant from IQ cannot be adequately
differentiated from poor readers whose reading skills are not discrepant from IQ (e.g.
Fletcher et al., 2002a, 2002b; Joshi, 2003; Lyon, Fletcher & Barnes, 2002; Seigel, 1989;
Sternberg & Grigorenko, 2002; Vellutino, Scanlon & Lyon, 2000). Consequently,
therefore, psychologists are tending to place less emphasis on discrepancy and more
emphasis on cognitive indicators such as verbal memory, rapid naming and phonological
awareness. However, there is a counter-argument in favour of retaining a role for
discrepancy: Kavale (2005) and Thompson (2003) argue that there is still a relevant
place for discrepancy because only measures of discrepancy can document the
unexpected nature of the problem. The existence of a discrepancy indicates the
presence of underachievement but only the possibility of dyslexia.
4.1.2 Predictors of reading difficulty and dyslexia
Scarborough (1998) carried out a meta-analysis of studies of early predictors of reading
difficulties. The results are summarised in Table 8. It can be seen that the strongest
predictors include verbal memory, phonological awareness, letter identification, object
naming and general language skills. These findings have been replicated in a large
number of other studies carried out in several countries (e.g. Boscadin, Muthén, Francis
76 Intervention for Dyslexia