Dyslexia—Part 1 of 2: Defining Dyslexia

This white paper explores dyslexia, a neurobiological learning disability characterized by difficulties in word recognition, spelling, and decoding despite adequate intelligence and instruction. It provides a detailed definition validated by international researchers, emphasizing phonological deficits as the root cause. Dyslexia is described as a spectrum disorder, ranging from mild to severe, and its manifestation varies across languages due to differences in orthographic transparency. The paper highlights over a century of research, including contributions from pioneers like Samuel Orton and Anna Gillingham, and recent advancements in brain imaging technologies that have transformed understanding. It dispels common myths, such as dyslexia being caused by vision problems or linked to low intelligence. Advocacy efforts by parents have led to significant legislative progress, including mandatory teacher training, early screening, and intervention programs in over 40 states. While dyslexia cannot be cured, early detection and explicit intervention can help students become confident readers and writers.