The chapter discusses the methods and previous explanations of aphasia and related speech disorders. The author, Henry Head, emphasizes the importance of serial tests to assess speech abilities, including naming and recognizing objects, colors, and performing tasks like the man, cat, and dog test, the clock test, the coin-bowl test, and the hand, eye, and ear tests. These tests help in understanding the specific deficits in speech production. Previous explanations of aphasia have been criticized for their reliance on the localization of faculties in the brain and the destruction of images. Head argues that aphasia is not a pure motor or sensory disorder but a complex disturbance of symbolic thinking and expression. He highlights the dissociated forms of these disorders, such as verbal, nominal, syntactical, and semantic defects, and emphasizes the need to consider speech as part of the broader mind rather than a separate faculty. The chapter also reviews the historical context, including the work of Gall, Broca, Hughlings Jackson, and Wernicke, and their contributions to understanding aphasia. Head's own research focuses on soldiers wounded in World War I, using their cases to explore the physiological aspects of speech disorders, rather than anatomical ones. He stresses the importance of systematic and detailed observations to understand the nature of these disorders and their progression over time.The chapter discusses the methods and previous explanations of aphasia and related speech disorders. The author, Henry Head, emphasizes the importance of serial tests to assess speech abilities, including naming and recognizing objects, colors, and performing tasks like the man, cat, and dog test, the clock test, the coin-bowl test, and the hand, eye, and ear tests. These tests help in understanding the specific deficits in speech production. Previous explanations of aphasia have been criticized for their reliance on the localization of faculties in the brain and the destruction of images. Head argues that aphasia is not a pure motor or sensory disorder but a complex disturbance of symbolic thinking and expression. He highlights the dissociated forms of these disorders, such as verbal, nominal, syntactical, and semantic defects, and emphasizes the need to consider speech as part of the broader mind rather than a separate faculty. The chapter also reviews the historical context, including the work of Gall, Broca, Hughlings Jackson, and Wernicke, and their contributions to understanding aphasia. Head's own research focuses on soldiers wounded in World War I, using their cases to explore the physiological aspects of speech disorders, rather than anatomical ones. He stresses the importance of systematic and detailed observations to understand the nature of these disorders and their progression over time.