Intervention for Dyslexia - The British Dyslexia Association

Co-occurring difficulties may be seen in aspects of language, motor coordination,
mental calculation, concentration and personal organisation, but
these are not, by themselves, markers of dyslexia.
A good indication of the severity and persistence of dyslexic difficulties can be
gained by examining how the individual responds or has responded to well
founded intervention.
1.2.2 United States of America
In the USA, the International Dyslexia Association proposed the following definition of
dyslexia, which has been widely accepted:
“Dyslexia is one of several distinct learning disabilities. It is a specific language-based
disorder of constitutional origin characterized by difficulties in single word decoding”
(Lyon, 1995, p. 7)
However, in the USA the term ‘dyslexia’ does not have a legal meaning; instead the term
‘Learning Disabilities’ is used (typically abbreviated to ‘LD’), which was defined in US
federal law as:
“A severe discrepancy between achievement and intellectual ability in one or more of
the areas: (1) oral expression; (2) listening comprehension; (3) written expression; (4)
basic reading skills; (5) reading comprehension; (6) mathematics calculation; or (7)
mathematics reasoning. The child may not be identified as having a specific learning
disability if the discrepancy between ability and achievements is primarily the result of:
(1) a visual, hearing or motor handicap; (2) mental retardation; (3) emotional
disturbance; or (4) environmental, cultural, or economic disadvantage.”
(US Office of Education, 1977, p. G1082)
The use of an IQ–achievement discrepancy criterion began to be popular during the
1970s (Rutter & Yule, 1975, Singleton, 1977) and subsequently found its way into
definitions of specific reading disorder in the two international professional manuals on
diagnosis: DSM-IV and ICD-10. For many years IQ–achievement discrepancy was
commonly used by educational psychologists for identifying dyslexia or specific learning
disabilities (see Singleton, 1987, 1988). However, subsequent research findings have
undermined its validity (for review, see Stuebing et al., 2002). In particular, there is little
evidence that the long-term development of poor readers who are IQ–achievement
discrepant is substantially different to that of poor readers who are not IQ–achievement
discrepant (Shaywitz et al., 1999), nor does IQ–achievement discrepancy reliably
distinguish between those who are difficult to remediate and those who are more easily
remediated (Vellutino et al., 2000; Meyer, 2000). Consequently, IQ–achievement
discrepancy is no longer the bedrock for identification of LD in the US (or of dyslexia in
the UK, for that matter), although on both sides of the Atlantic strong cases have been
made in favour of retaining the use of IQ assessment as part of the identification
process (see Kavale, 2005; Thomson, 2003).
The US federal definition of LD has been widely criticized (see Kavale & Forness, 2000;
Lyon et al., 2001) and in 2004 the US Congress passed statutes that allowed for LD to
be identified without recourse to IQ–achievement discrepancy, including use of the
response to intervention approach (RTI), which is considered in more detail in Section
4.1.3.
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