01 NRDC Dyslexia 1-88 update - Texthelp

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Research Report
Differences between languages and their writing and spelling systems create a form of
cultural bias in dyslexia.
Differences in discriminative criteria for educational failure between the social classes
create a reporting bias in dyslexia.
Differences in the effects of IQ-discrepancy operational criteria create an identification
bias in dyslexia.
Can the research findings be applied to adults in literacy and numeracy classes?
Adult dyslexic people taking part in research carried out in cognitive psychology and
neuroimaging laboratories tend to be either university students or mature adults who had
attended specialist schools or clinics as children. Both scientific exclusionary criteria
(Vellutino, 1979) and cultural self-selection have thus led to a research population which is, by
destination if not by origin, predominantly white-collar. Research with greater numbers of
working-class participants has indicated important socio-economic differences in the nature
of reading skills deficits. Even if that were not the case, it would be rash to generalise
research findings to populations dissimilar from those involved in the research. As it is, recent
findings suggest that such generalisations may often be misleading. To the extent that adults
in basic skills classes are working-class or second-language speakers of English, the
research literature on dyslexia (as distinct from that on reading disability) may not apply to
most to them.
Findings from research with participants from middle-class groups may create misleading
expectations about the needs and abilities of learners in adult literacy classes.
The crux of the problem
Heterogeneity in ‘dyslexia’ is generally acknowledged. It may reflect the fact that complex
systems break down in complex ways (Seidenberg, 1992). It may also reflect differences in
concepts and methods of identification (Filipek, 1999). In the latter case, it would reflect
laboratory practice, since most research into developmental dyslexia ‘seems content to lump
together individuals with grossly different reading profiles in a way that would never be
accepted in the field of acquired dyslexia’ (Ellis et al., 1997a).
The consequence of heterogeneity is that no generalisation is valid for each and every
member of the population of adults who have been identified (or who have identified
themselves) as ‘dyslexic’. Diagnoses (and self-diagnoses) are unstable, both across methods
of identification and—in the case of diagnoses if not self-diagnoses—over time. Some of these
diagnoses, including allocation to subtypes, are artefacts of research and teaching methods.
Some, especially in the case of people whose literacy ability is discrepant in relation to their
perceived intelligence because they have been poorly taught or because they have grown up in
an environment where schooling and literacy are under-valued, may be more appropriately
replaced by diagnoses of ordinary poor reading’, which has also been referred to as
‘pseudodyslexia’ (Morton & Frith, 1995; Perfetti & Marron, 1995).
Does this mean that we cannot define developmental dyslexia? Or that, once we have defined