Dr. Samuel Orton believed dyslexia was caused primarily by differences in which part of the brain?

Dr. Samuel Orton, a pioneer in the study of reading disabilities and dyslexia, believed that the primary cause of dyslexia lies in differences associated with the left hemisphere of the brain. This hemisphere is integral to language processing, including tasks such as reading and writing. Orton's research identified that individuals with dyslexia often exhibit unique patterns of brain functioning that suggest a disruption in the areas responsible for phonological processing, which predominantly occurs in the left hemisphere, particularly in areas such as Broca's area and Wernicke's area.

Orton's work laid the foundation for further exploration into the neurological underpinnings of dyslexia, influencing educational approaches and therapeutic interventions aimed at supporting individuals with this learning difference. His emphasis on the left hemisphere aligns with contemporary understanding that suggests difficulties in phoneme awareness and decoding—core aspects of mastering reading skills—are closely linked to this part of the brain.