Intervention for Dyslexia - The British Dyslexia Association

some validity in cases of students with severe dyslexia because such individuals should
respond more slowly to intervention, if at all. However, RTI is less likely to identify as
dyslexic a student whose inherent phonological difficulties were mild (because these
students should respond well to explicit and intensive instruction).
4.2 Issues in screening
4.2.1 The purpose of screening
The general purpose of screening is the identification of a sub-group from within a
larger group or population. The original meaning of the term ‘screening’ was to sieve
materials such as coal through a coarse mesh (or ‘screen’) in order to eliminate
unwanted matter such as stones or dust. Such a method, although by no means perfect,
had the advantage of being speedy and much more economical than having to sort the
materials by hand. Screening, therefore, was an acceptable but essentially rough-andready
approach, and the term has partly (but not entirely) retained this nuance. In its
metaphorical sense, the term became popular in medicine, referring first to procedures
for identifying in the general population those suffering from a particular disorder (e.g.
screening for tubercular lesions by X-ray examination of the lungs) and later to
procedures for identifying individuals believed to be at risk of certain disorders (e.g.
genetic screening). In the medical context, however, the idea of screening being a
rough-and-ready solution to identification steadily gave way to expectations that
screening will have fairly high degrees of accuracy and reliability. Periodically there are
concerns about accuracy of various medical screening techniques and, in particular,
about the rate of false negatives, i.e. cases where screening has not revealed a risk but
in which illness subsequently developed. Such concerns reflect not only the awareness
that the consequences of false negatives in medical screening are likely to be serious,
but also the high cost of medical intervention and the fact that treatment may be
harmful if administered to a patient who does not actually require it.
4.2.2 Screening in education
In education, screening has acquired a meaning somewhere between the original use of
the term as a rough-and-ready selection process, and the sense now expected in
medicine, where reasonably high levels of accuracy are expected. Sometimes, however,
commentators seem to be unsure about exactly where, between those two extremes,
educational screening properly lies. The consequences of inaccuracy in educational
screening might not be as grave as in medical screening, but they are considerably more
important than leaving a piece of rock in a bag of coal. If a child who does have a real
learning difficulty is shown by a screening procedure to be ‘not at risk’ (i.e. a ‘false
negative’) it is unlikely that the child will receive the proper help they need. Moreover,
the teachers may quite understandably believe that the child’s poor reading attainment
and other problems are the result of lack of effort rather than, say, any constitutional
condition. Under these circumstances, the child may well become discouraged and lose
motivation and confidence. Hence the child’s problems could become compounded by
the outcome of an inaccurate screening process.
In addition to being reasonably accurate, screening instruments are often required to
meet certain practical requirements. Satz and Fletcher (1979) have commented: “True
screening is rapid and cost effective and does not require professional interpretation.”
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