| I agree, the numerical results are poorly presented. What was measured was wether their tests can find a dominant eye in the subject or not as well as the difference in Maxwell's centroids between both eyes. Eye dominance results: They had two types of test for this; the sighting test and the after-image test. For the control group they found a dominant eye in 28 of the sighting tests and 30 in the after-image tests. In the 28 cases where they found a dominant eye with both tests, the tests corresponded perfectly, i.e. if the sighting test indicated the right eye was dominant the after-imagetest also did. For the dyslexic group the sighting test found a dominant eye for 14 subjects, and the after-image test for 3. In the 3 cases where they found a dominant eye with both tests, the results corresponded perfectly. Maxwell's centroids result: For the control group they showed that in 29 cases the asymmetry between the centroids was at least above 0.3 (as far as I can tell from the figures), where 0.3 means "weak asymmetry" and 0.6 means "strong asymmetry". One case was slightly above 0.2. For the dyslexic group 27 cases had ~0.0 in the asymmetry measure. 2 above 0.3 and one slightly below 0.3. I have generalized a bit and labeled results ranging from 0.3 to 0.5 as "above 0.3". |
In order to have some sense of how these findings relate to the notion of "dyslexia" as used in public life in western countries we obviously need to look at how the case cohort was selected. They say:
> all encountered difficulties in reading, spelling, writing and recognizing left from right
Presumably that means that every one of the 30 had problems with all 4 of those tasks. Possibly this is a narrower definition than that used by the public / educational psychologists -- I think they often diagnose dyslexia without requiring left/right confusion as a symptom?