Going back a few years, see:
Evidence that dyslexia may represent the lower tail of a normal
distribution of reading ability
SE Shaywitz, MD Escobar, BA Shaywitz, JM Fletcher, and R Makuch
NEJM Volume 326:145-150 January 16, 1992 Number 3
Abstract
BACKGROUND. Dyslexia is now widely believed to be a biologically
based disorder that is distinct from other, less specific reading
problems. According to this view, reading ability is considered to
follow a bimodal distribution, with dyslexia as the lower mode. We
hypothesized that, instead, reading ability follows a normal
distribution, with dyslexia at the lower end of the continuum.
METHODS AND RESULTS. We used data from the Connecticut Longitudinal
Study, a sample survey of 414 Connecticut children who entered
kindergarten in 1983 and were followed as a longitudinal cohort.
Dyslexia was defined in terms of a discrepancy score, which
represents the difference between actual reading achievement and
achievement predicted on the basis of measures of intelligence. Data
were available from intelligence tests administered in grades 1, 3,
and 5 and achievement tests administered yearly in grades 1 through
6. For each child there were 108 possible discrepancy scores ([3 x 3
years] x [2 x 6 years]) based on combinations of the ability scores
(full-scale, verbal, and performance IQ) in each of three years and
two achievement scores (reading and mathematics) in each of six
years. We demonstrated that each of the discrepancy scores followed a
univariate normal distribution and that the interrelation of two
different discrepancy scores followed a bivariate normal
distribution. At most, only 9 of 108 discrepancy scores (8.3 percent)
and 171 of 3402 pairs of discrepancy scores (5.0 percent) were
significantly different (at the 5 percent level) from the expected
scores--well within the expected values for data with univariate and
bivariate normal distributions, respectively. We also examined the
stability of dyslexia over time. The normal-distribution model
predicted (and the data indicated) that only 7 of the 25 children (28
percent) classified as having dyslexia in grade 1 would also be
classified as having dyslexia in grade 3. CONCLUSIONS. Reading
difficulties, including dyslexia, occur as part of a continuum that
also includes normal reading ability. Dyslexia is not an all-or-none
phenomenon, but like hypertension, occurs in degrees. The variability
inherent in the diagnosis of dyslexia can be both quantified and
predicted with use of the normal-distribution model.
Of course, it IS by Sally Shaywitz ....
At 8:53 PM -0500 1/22/07, [EMAIL PROTECTED] wrote:
It seems a huge controversy has develloped concerning the view of the
British educational psychologist Julian Elliott that dyslexia as an
identifiable disability requiring special intervention is a myth.
I love mythbusters. And I've always suspected something of the sort about
dyslexia as well, although I could never have expressed it as
articulately and persuasively as Dr. Elliott does. It appears, not
surprisingly, that parents of dyslexic children are not too happy with
his idea.
The Telegraph just last week published an article by David Mills on the
controversy, on-line Jan 15, 2007, "Dyslexia: a big, expensive myth".
http://tinyurl.com/2lgo98
http://www.telegraph.co.uk/health/main.jhtml?xml=/health/2007/01/15/hdysle
xia15.xml&page=3
And an earlier and probably more informative article was published two
years earlier in The Guardian by Joanna Moorhead (September 7, 2005)
http://www.guardian.co.uk/parents/story/0,,1564251,00.html
There's also a short version of Elliott's views in TES ( Times
Educational Supplement, right?), September 2, 2005:
"Dyslexia myths and the feel-bad factor"
http://www.tes.co.uk/search/story/?story_id=2128733
I haven't, however, been able to dig up an academic publication of
Elliott's on the topic.
--
The best argument against Intelligent Design is that fact that
people believe in it.
* PAUL K. BRANDON [EMAIL PROTECTED] *
* Psychology Dept Minnesota State University *
* 23 Armstrong Hall, Mankato, MN 56001 ph 507-389-6217 *
* http://krypton.mnsu.edu/~pkbrando/ *
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