Dyslexia: 1965–2005

Abstract

William Yule's many contributions to the field of reading disabilities over the last 40 years are reviewed and set in the context of recent research evidence. The value of regression methods in the measurement of reading performance remains valid, but spelling, as well as reading, difficulties need to be assessed in relation to the diagnosis of dyslexia. Although categorical approaches to diagnosis are needed for some purposes, it is likely that the genetic liability to dyslexia is dimensional. Overall, Yule's identification of the key features of specific reading retardation have been confirmed by subsequent research, but the concept of general reading backwardness as a diagnosis has proved less meaningful. The identification of the high rate of comorbidity between reading disability and emotional/behavioural disturbance, highlighted by Yule 35 years ago, has been amply confirmed but the causal mechanisms remain ill-understood.