Introduction

Specific reading disabilities in children of normal intelligence were described for the first time by Kerr (1896) and later in the same year by Morgan (1896) who introduced the term “congenital word-blindness”. This term has subsequently been used in the majority of medical publications, although it has been the subject of much controversy. In my opinion, the most cogent objection to the term is that it only implies a disturbance in the visual perception of words-cf., for example, Bachmann (19271, Illing (19291, Thiele (1938), KigCn (1943), Tamm (1943) and Ombredane (1944). No clear and uniform definition of the disorder exists. Skydsgaard (1942) summarized the view generally accepted in the medical literature as follows: “Congenital dyslexia (a term which, on the whole, covers the condition commonly named word-blindness) denotes in clinical medicine primary constitutional reading difficulties which may occur electively and which, in their pure form, differ distinctly from reading difficulties of other (endogenous or exogenous) origin.”% From a clinical point of view, Skydsgaard drew the borderline between “constitutional dyslexia” and “physiological variants’’ at the level where taking into consideration the influence of exogenous factors normal reading ability could not be attained with the use of the customary teaching methods. This borderline is, however, indefinite and varies in the works of different authors. A large number of publications followed Kerr’s first report. The earlier papers dealt mainly with severe cases. More re-