The relationship between the two cerebral hemispheres with regard to dyslexia has been thought to be in some way anomalous ever since Orton first popularized the idea. Quite how dyslexics differ from normal readers was not always specified, although one proposal was that if dyslexia represented a developmental lag, then it must be the left hemisphere that is the laggard (see Chapter 2). Such ideas were difficult to test with the empirical methods then available, even allowing for conceptual woolliness. After reviewing the main theories and evidence, Hiscock and Kinsbourne (1982) wrote: “It must be concluded that, despite the current popularity of hemisphere-related explanations for dyslexia, there are strong logical and empirical arguments contrary to those explanations. Several decades have passed since it was first proposed that some forms of dyslexia stem from irregularities of cerebral lateralization, but the thesis remains unproven” (p. 218).