This book provides a detailed examination of the science of synesthesia. Cytowic and Eagleman are leading synesthesia researchers. In this book, they present a detailed description of synesthesia, providing a catalog of synesthesia experiences and an overview of current theories of how these experiences come about. Types of synesthesia experiences are enumerated in the first part of the book, with separate chapters devoted to graphemes provoking colors, sounds provoking colors, spatial sequences provoking forms, sensations involving taste, and emotional triggers and synesthetic sensations. The authors also discuss the connection of synesthesia experiences to metaphor and art before delving into the neuropsychology and science behind synesthesia. The book is well documented with endnotes citing numerous published studies and an extensive bibliography.
This book is a very formal description of synethestic phenomena, but still accessible to general readers. I didn't find the first part of the book, in which the various kinds of synthestic experiences are described in detail, particularly engaging, but others, especially those who experience synesthesia themselves may be reassured in finding that synesthesia is indeed a recognized and normal part of the human experience for many people. I found the last part of the book, in which the authors describe the varying theories behind synesthesia quite informative and thought-provoking. The authors argue that "synesthesia is a latent capacity in everyone." They remind us that seeing is a matter of perception in the brain, not a direct reflection of the physical environment. And finally, they point out that synesthesia may only be the tip of the iceberg for cross talk within the brain, noting "What would be the consequence of increased cross talk between brain regions that are not sensory--for example, between frontal areas involved in cognition or moral reasoning? What happens when areas involved in memory and planning express higher than normal interaction? Could this be the basis of increased creativity, intelligence, or madness? Our future understanding of the mechanism of synesthesia may shed light on mental, cognitive, and emotional talents or disorders."