1.5 Defining dyslexia
The ongoing debate about dyslexia is reflected in the different approaches that have been taken to formally define it. Clearly this impacts on how dyslexia is defined in practice. The next three sections summarise how definitions of dyslexia have changed as our knowledge has increased. In short, there have been three main approaches to defining dyslexia: definition by exclusion, discrepancy definitions and the identification of positive indicators.